BS EN ISO 15848-1-2015Industrial valves-Measurement, test and qualification procedures for fugitive emissions

BS EN ISO 15848-1:2015
BSI Standards Publication
Industrial valves —
Measurement, test and
qualification procedures for
fugitive emissions
Part 1: Classification system and
qualification procedures for type testing of
valvesBS EN ISO 15848-1:2015 BRITISH STANDARD
National foreword
This British Standard is the UK implementation of EN ISO
15848-1:2015. It supersedes BS EN ISO 15848-1:2006 which is
withdrawn.
The UK participation in its preparation was entrusted to Technical
Committee PSE/18/1, Industrial valves, steam traps, actuators and
safety devices against excessive pressure - Valves - Basic standards.
A list of organizations represented on this committee can be
obtained on request to its secretary.
This publication does not purport to include all the necessary
provisions of a contract. Users are responsible for its correct
application.
? The British Standards Institution 2015.
Published by BSI Standards Limited 2015
ISBN 978 0 580 82087 8
ICS 23.060.01
Compliance with a British Standard cannot confer immunity from
legal obligations.
This British Standard was published under the authority of the
Standards Policy and Strategy Committee on 30 June 2015.
Amendments/corrigenda issued since publication
Date
d etc effa tx e T
EUROPEAN STANDARD
EN ISO 15848-1

NORME EUROPéENNE

EUROP?ISCHE NORM
June 2015
ICS 23.060.01 Supersedes EN ISO 15848-1:2006
English Version
Industrial valves - Measurement, test and qualification
procedures for fugitive emissions - Part 1: Classification system
and qualification procedures for type testing of valves (ISO
15848-1:2015)
Robinetterie industrielle - Mesurage, essais et modes Industriearmaturen - Mess-, Prüf- und
opératoires de qualification pour émissions fugitives - Partie Qualifikationsverfahren für flüchtige Emissionen - Teil 1:
1: Système de classification et modes opératoires de Klassifizierungssystem und Qualifikationsverfahren für die
qualification pour les essais de type des appareils de Bauartprüfung von Armaturen (ISO 15848-1:2015)
robinetterie (ISO 15848-1:2015)
This European Standard was approved by CEN on 7 February 2015.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITé EUROPéEN DE NORMALISATION

EUROP?ISCHES KOMITEE FüR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
? 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 15848-1:2015 E
worldwide for CEN national Members. BS EN ISO 15848-1:2015
EN ISO 15848-1:2015 (E)
Foreword
This document (EN ISO 15848-1:2015) has been prepared by Technical Committee ISO/TC 153 “Valves” in
collaboration with Technical Committee CEN/TC 69 “Industrial valves” the secretariat of which is held by
AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by December 2015, and conflicting national standards shall be withdrawn
at the latest by December 2015.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 15848-1:2006.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 15848-1:2015 has been approved by CEN as EN ISO 15848-1:2015 without any modification.
3 BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Contents Page
Foreword ........................................................................................................................................................................................................................................iv
Introduction ................................................................................................................................................................................................................................vi
1 Scope ................................................................................................................................................................................................................................. 1
2 Normative references ...................................................................................................................................................................................... 1
3 Terms and definitions ..................................................................................................................................................................................... 1
4 Symbols and abbreviations ....................................................................................................................................................................... 3
5 Type test ........................................................................................................................................................................................................................ 4
5.1 Test conditions ........................................................................................................................................................................................ 4
5.1.1 Preparation of a valve to be tested ................................................................................................................... 4
5.1.2 Test fluid .................................................................................................................................................................................. 4
5.1.3 Test temperature ............................................................................................................................................................. 4
5.1.4 Measurement of test valve temperature...................................................................................................... 4
5.1.5 Leakage measurement ................................................................................................................................................ 7
5.2 Test procedures ...................................................................................................................................................................................... 8
5.2.1 Safety rules............................................................................................................................................................................ 8
5.2.2 Test equipment .................................................................................................................................................................. 8
5.2.3 Stem (or shaft) seal adjustment (SSA) .......................................................................................................... 8
5.2.4 Test description ................................................................................................................................................................ 9
6 Performance classes ......................................................................................................................................................................................11
6.1 Classification criteria ......................................................................................................................................................................11
6.2 Tightness classes ................................................................................................................................................................................11
6.2.1 Definition .............................................................................................................................................................................11
6.2.2 Helium as test fluid .....................................................................................................................................................12
6.2.3 Methane as test fluid .................................................................................................................................................12
6.2.4 Correlations .......................................................................................................................................................................12
6.3 Endurance classes .............................................................................................................................................................................12
6.3.1 Mechanical-cycle classes for isolating valves .......................................................................................12
6.3.2 Mechanical-cycle classes for control valves...........................................................................................14
6.4 Temperature classes ........................................................................................................................................................................15
6.5 Examples of class designation ................................................................................................................................................16
6.6 Marking ......................................................................................................................................................................................................16
7 Reporting ...................................................................................................................................................................................................................16
8 Extension of qualification to untested valves ......................................................................................................................17
Annex A (normative) Total leak rate measurement ..........................................................................................................................19
Annex B (normative) Leak measurement using the sniffing method .............................................................................32
Annex C (informative) Leak rate conversion (helium) ...................................................................................................................41
Bibliography .............................................................................................................................................................................................................................43
? ISO 2015 – All rights reserved iiiBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT), see the following URL: Foreword — Supplementary information.
The committee responsible for this document is ISO/TC 153, Valves, Subcommittee SC 1, Design,
manufacture, marking and testing.
This second edition cancels and replaces the first edition (ISO 15848-1:2006) which has been technically
revised. The main changes are the following:
?1
— leak rate at the stem seal (Table 1) is expressed in mbar?l?s per mm stem diameter;
— flushing method is replaced by accumulation or suck through method to measure leak rate from
stem seal with Helium (Annex A);
— leakage is expressed in ppmv; leakage with methane is measured by sniffing;
?7 ?1 ?1 ?5 ?1 ?1
— for tightness Class AH, leak rate ≤ 1,78·10 mbar?l?s ?mm (10 mg?s ?m );
— the appropriate leak rate is given for Classes BH and CH;
— addition of Table 3 which gives tightness classes for stem (or shaft) seals with methane;
— there is no correlation intended between the tightness classes when the test fluid is helium (Classes
AH, BH, CH) and when the test fluid is methane (Classes AM, BM, CM);
— modification of the number of mechanical cycles for isolating valves;
— addition of Table 4;
— addition of Figures 3, 4, and 5;
— addition of type leak (A.1.3.4, B.1.4.2, B.1.6.1);
— modification of Figure B.2;
— modification of B.1.6.1 on calibration procedures;
— deletion of Figure B.3;
iv ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

— addition of Table C.1 and modification of Table C.2.
ISO 15848 consists of the following parts, under the general title Industrial valves — Measurement, test
and qualification procedures for fugitive emissions:
— Part 1: Classification system and qualification procedures for type testing of valves
— Part 2: Production acceptance test of valves
? ISO 2015 – All rights reserved vBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Introduction
The objective of this part of ISO 15848 is to enable classification of performance of different designs and
constructions of valves to reduce fugitive emissions.
This part of ISO 15848 defines type test for evaluation and qualification of valves where fugitive
emissions standards are specified.
The procedures of this part of ISO 15848 can only be used with the application of necessary precautions
for testing with flammable or inert gas at temperature and under pressure.
vi ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
INTERNATIONAL STANDARD ISO 15848-1:2015(E)
Industrial valves — Measurement, test and qualification
procedures for fugitive emissions —
Part 1:
Classification system and qualification procedures for type
testing of valves
1 Scope
This part of ISO 15848 specifies testing procedures for evaluation of external leakage of valve stem
seals (or shaft) and body joints of isolating valves and control valves intended for application in volatile
air pollutants and hazardous fluids. End connection joints, vacuum application, effects of corrosion, and
radiation are excluded from this part of ISO 15848.
This part of ISO 15848 concerns classification system and qualification procedures for type testing of
valves.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 5208, Industrial valves — Pressure testing of metallic valves
EN 13185:2001, Non-destructive testing — Leak testing — Tracer gas method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
body seals
any seal in pressure containing part except stem (or shaft) seals
3.2
Class
convenient round number used to designate pressure-temperature ratings
Note 1 to entry: It is designated by the word “Class” followed by the appropriate reference number from the
following series: Class 125, Class 150, Class 250, Class 300, Class 600, Class 900, Class 1 500, Class 2 500.
3.3
concentration
ratio of test fluid volume to the gas mixture volume measured at the leak source(s) of the test valve
1)
Note 1 to entry: The concentration is expressed in ppmv .
3 3 3
1) Parts per million volume is a unit deprecated by ISO. 1 ppmv = 1 ml/m = 1 cm /m .
? ISO 2015 – All rights reserved 1BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

3.4
control valve
power operated device which changes the fluid flow rate in a process control system and which consists
of a valve connected to an actuator that is capable of changing the position of a closure member in the
valve in response to a signal from the controlling system
3.5
fugitive emission
chemical or mixture of chemicals, in any physical form, which represents an unanticipated or spurious
leak from equipment on an industrial site
3.6
leakage
loss of the test fluid through the stem (or shaft) seal or body seal(s) of a test valve under the specified
test conditions and which is expressed as a concentration or a leak rate
3.7
leak rate
?1
mass flow rate of the test fluid, expressed in mg·s per millimetre of stem diameter through stem seal
–1
system or volumic flow rate of the test fluid, expressed in mbar?l?s per millimetre of stem diameter
through stem seal system
3.8
local leakage
measurement of the test fluid leakage using a probe at the leak source point
3.9
mechanical cycle of control valves
for linear/rotary control valves, test cycles performed at 50 % of stroke/angle with an amplitude of
±10 % of full stroke/angle
3.10
mechanical cycle of isolating valves
motion of a valve obturator moving from fully closed position to fully opened position, and returning to
fully closed position
3.11
nominal size
DN
alphanumeric designation of size for components of a pipework system, which is used for reference
purposes, comprising the letters DN followed by a dimensionless whole number which is indirectly
related to physical size, in millimetres, of the bore or outside diameter of the end connections
Note 1 to entry: The nominal diameter is designated by the letters DN followed by a number from the following
series: 10, 15, 20, 25, 32, 40, 50, 65, 80, 100, 125, 150, 200, 250, 300, 350, 400, etc.
Note 2 to entry: The number following the letters DN does not represent a measurable value and should not be
used for calculation purposes except where specified in the relevant standard.
Note 3 to entry: Adapted from ISO 6708:1995, definition 2.1.
3.12
nominal pressure
PN
numerical designation relating to pressure, which is a convenient rounded number for reference
purposes, comprising the letters PN followed by the appropriate reference number
Note 1 to entry: All equipment of the same nominal size (DN) designated by the same PN number have compatible
mating dimensions.
Note 2 to entry: The maximum allowable working pressure depends upon materials, design, and working
temperatures and is selected from the pressure/temperature rating tables in the appropriate standards.
2 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Note 3 to entry: The nominal pressure is designated by the letters PN followed by the appropriate reference
number from the following series: 2,5, 6, 10, 16, 20, 25, 40, 50, etc.
Note 4 to entry: Adapted from ISO 7268:1983, definition 2.1.
3.13
isolating valve
valve intended for use principally in the closed or open position which can be power actuated or manually
operated
3.14
performance class
level of the performance of a test valve
Note 1 to entry: The performance classes are defined in Clause 6.
3.15
room temperature
temperature in the range of ?29 °C to +40 °C
3.16
stem
shaft
valve component extending into the valve shell to transmit the linear/rotary motion from the actuating
device to the valve obturator
3.17
stem seal
shaft seal
component(s) installed around the valve stem (or shaft) to avoid leakage of internal fluids to atmosphere
3.18
test pressure
pressure used for testing the valve which, unless otherwise specified, is the rated pressure specified at
the test temperature and the shell material of a test valve in the relevant standards
3.19
test temperature
fluid temperature selected for the test as measured inside the test valve
Note 1 to entry: The test temperature is given in Table 5.
3.20
thermal cycle
change of the temperature from the room temperature to the specified test temperature and return to
the room temperature
3.21
total leakage
collection of leakage of the test fluid at the leak source using an encapsulation method
3.22
type test
a test conducted to establish the performance class of a valve
4 Symbols and abbreviations
M predicted maximum leakage
alr
SSA stem (or shaft) seal adjustment
? ISO 2015 – All rights reserved 3BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

OD stem outside diameter
stem
RT room temperature
NOTE The abbreviation SSA corresponds to the abbreviation of “Stem Seal Adjustment”.
5 Type test
5.1 Test conditions
5.1.1 Preparation of a valve to be tested
Only a fully assembled valve shall be used for the test.
A valve shall be selected from standard production at random. The valve shall have been tested and
accepted in accordance with ISO 5208 or any other applicable standard and no subsequent protective
coating shall have been applied.
Additional seal arrangements to allow the stem sealing system leakage measurement is permitted and
shall not affect the sealing performance of the valve.
The test valve interior shall be dried and lubricants (if any) shall be removed. The valve and test
equipment shall be clean and free of water, oil, and dust and the packing may be changed prior to the
test. If the valve packing is changed prior to the test, it should be done under the supervision of the valve
manufacturer.
If a test valve is equipped with a manually adjustable stem (or shaft) seal(s), it shall be initially adjusted
according to the manufacturer’s instructions and recorded in the test report as provided in Clause 7.
The valve manufacturer shall select the appropriate actuating device.
5.1.2 Test fluid
The test fluid shall be helium gas of 97 % minimum purity or methane of 97 % minimum purity. The
same test fluid shall be used throughout the test.
5.1.3 Test temperature
Valve mechanical cycling is carried out at the room temperature or in the steps of the room temperature
and the selected test temperature other than the room temperature (see 5.2.4.1).
The test temperature shall be recorded for each leakage measurement.
5.1.4 Measurement of test valve temperature
The temperature of the test valve shall be measured at three locations, as shown in Figure 1, and
recorded in a test report.
a) Measurement at location 1 shall be used to determine the test temperature.
b) Measurement at location 2 is also made for information. Any use of insulation shall be detailed in
the test report.
c) Measurement at location 3 is used to determine the external valve temperature adjacent to the stem
(or shaft) seal(s) for information.
d) Measurement at location 4 is an option if measurement location 1 is not possible (except in the case
where heating elements penetrate the blind flanges).
4 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

All temperatures at location 1, 2, and 3 (and 4) shall be stabilized before leakage is measured (see
Figures 2 and 3). Temperature at location 3 shall be stabilized for minimum 10 min prior to leakage
measurement.
Check if the temperature variation is within ±5 %.
Key
1 location 1: flow path (temperature T )
1
2 location 2: valve body (temperature T )
2
3 location 3: stuffing box (temperature T )
3
4 location 4: optional for flow path (temperature T )
1
Figure 1 — Measurements of temperature
? ISO 2015 – All rights reserved 5BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Key
T test temperature, °C
test
T stabilization temperature at location 1 (flow path)
1
T stabilization temperature at location 2 (valve body)
2
T stabilization temperature at location 3 (stuffing box)
3
t time
t stabilization of temperature at location 3 (stuffing box)
0
t + 10 min start of mechanical cycles
0
Figure 2 — Stabilization of temperatures (when the valve is internally heated or cooled)
6 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Key
T test temperature, °C
test
T stabilization temperature at location 1 (flow path)
1
T stabilization temperature at location 2 (valve body)
2
T stabilization temperature at location 3 (stuffing box)
3
t time
t stabilization of temperature at location 3 (stuffing box)
0
t + 10 min start of mechanical cycles
0
Figure 3 — Stabilization of temperatures (when the valve is externally heated or cooled)
5.1.5 Leakage measurement
5.1.5.1 Stem (or shaft) leakage measurement
Leakage shall be measured from a test valve at rest in the partly open position.
The leakage measurement shall be performed
— by the global method (vacuum or bagging) according to the procedures described in Annex A, or
— by the local leakage measurement (sniffing) according to the procedures described in B.2.
5.1.5.2 Body seal leakage measurement
The local leakage shall be measured by sniffing method according to the procedure described in Annex B.
Evaluation of the end connections should be done to ensure that they do not affect the results of the
evaluation of the body seals.
? ISO 2015 – All rights reserved 7BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

5.1.5.3 Leakage-measurement records
All results of leakage measurements shall be recorded in a test report as specified in Clause 7.
5.2 Test procedures
5.2.1 Safety rules
Testing with high pressure gas is potentially hazardous and thus all applicable local safety rules and
adequate safety measures shall be followed. If methane (CH ) is used, the combination of the test
4
pressure and temperature shall be reviewed for possible combustion concerns.
5.2.2 Test equipment
The test equipment shall be appropriately selected to
a) apply and maintain the test pressure within a range of ±5 % of the nominal value,
b) apply valve mechanical cycles,
c) heat or cool the test valve to the selected test temperature and maintain it within a range of ±5 %
but not exceeding 15 °C; no mechanical cycling is permitted during temperature change,
d) measure and record time, pressure, temperature, leakage, and duration of a valve mechanical cycle,
e) measure and record actuation forces or torques to operate a test valve, and
f) measure and record the stem sealing system loading, if applicable.
5.2.3 Stem (or shaft) seal adjustment (SSA)
5.2.3.1 Number of stem seal adjustment
Mechanical adjustments of stem (or shaft) sealing system during the type test shall be permitted only
once, as shown below, for each of qualification stage done according to Figures 4, 5, and 6, if stem
(or shaft) leakage has been measured in excess of the target tightness class selected from Tables 1 to 4.
The maximum retightening force (or torque) to apply shall be determined prior to the type test.
EXAMPLE
— A maximum of one adjustment is accepted for CC1 or CO1.
— A maximum of two adjustments is accepted for CC2 or CO2.
— A maximum of three adjustments is accepted for CC3 or CO3.
5.2.3.2 Test failure after stem seal adjustment
If a stem (or shaft) sealing arrangement fails to achieve the target tightness class, or it is not possible
to continue mechanical cycling, the test shall be considered terminated, and the test valve shall be
evaluated for qualification of lower tightness and endurance classes, if applicable.
5.2.3.3 Reporting the number of SSA
The total number of stem (or shaft) seal adjustment shall be recorded in the test report and indicated in
the designation of the valve classification as “SSA-1”, “SSA-2”, and “SSA-3”.
8 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

5.2.4 Test description
5.2.4.1 General
The test description is the following:
a) The test valve shall be mounted on a test rig, according to the instructions given by the manufacturer.
b) The valve mounting shall be principally made with a stem (or shaft) positioned vertical. A valve
intended for use in other positions shall be mounted with the stem (or shaft) positioned horizontally.
c) All sealing systems shall have been properly adjusted beforehand, according to the manufacturer’s
instructions. For valves using packings as a stem seal, the tightening torque of the gland boltings
shall be measured and recorded at the beginning of the test and after any stem seal adjustment.
d) The target number and combination of mechanical and thermal cycles shall be selected from the
endurance classes specified in Figures 4, 5, and 6.
e) Leakage from the stem (or shaft) seal and from the body seals shall be separately measured. If the
valve does not allow such a separate measurement, the total leakage of both stem (or shaft) and
body seals shall be measured at the same time according to Annex A and Annex B respectively.
f) Actual methods of mechanical cycles other than those specified in 5.2.4.2 and 5.2.4.3 shall be in
accordance with the manufacturer’s instructions, and opening, closing, and dwelling time shall be
recorded in the test report. Basically, they shall represent the intended operating conditions of a
test valve.
g) Valve opening and closing force (or torque) shall be measured and recorded at the start and at the
end of the test, following subsequent stem seal adjustments if applicable.
5.2.4.2 Mechanical cycles of isolating valves
Unless otherwise specified by the valve manufacturer, the valve seating force (or torque) required for
tightness under a differential pressure of 0,6 MPa (6 bar), air or inert gas shall be used as the minimum
force (or torque) for mechanical cycle of a test valve.
Fully back seating a test valve is not required.
5.2.4.3 Mechanical cycles of control valves
The stem motion of linear action valves shall be between 1 mm/s and 5 mm/s. The shaft motion of
rotary control valves shall be between 1°/s and 5°/s.
The actuator to operate a test valve shall withstand only the pressure and friction force (or torque)
acting on the valve stem, and these values shall be recorded.
NOTE Measurement of friction force (or torque) is principally intended to check the packing friction usually
expressed as the dead band.
5.2.4.4 Preliminary tests at the room temperature (test 1)
The tests are carried out as shown below.
a) Pressurize a test valve with the test fluid to the test pressure as specified in a relevant standard.
b) After the test pressure has been stabilized, measure leakages both from the stem (or shaft) seal and
from the body seals, in accordance with Annexes A and B, respectively.
c) Record the test result in a test report.
? ISO 2015 – All rights reserved 9BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

5.2.4.5 Mechanical cycle test at the room temperature (test 2)
The tests are carried out as shown below.
a) Perform mechanical cycles at room temperature while the test valve is kept pressurized.
b) Measure the leakage from the stem (or shaft) seal only, in accordance with Annex A.
c) Record the test result in the test report.
d) Repeat the test in case of Class CO1 and CC1, as indicated in Figures 4 and 6.
5.2.4.6 Static test at the selected test temperature (test 3)
The tests are carried out as shown below.
a) Pressurize a test valve with the test fluid to the test pressure as specified in a relevant standard for
the selected test temperature selected from Table 5.
b) After the test pressure has been stabilized, adjust the valve temperature to the selected test
temperature, ensuring that the test pressure does not exceed the level specified in the relevant
standard.
c) After the valve temperature has been stabilized with an allowance of ±5 % with a maximum of
15 °C, measure the leakage from the stem (or shaft) seal only in accordance with Annex A.
d) Record the test result in the test report.
e) Repeat the test in case of Class CO1 and CC1, as indicated in Figures 4 and 6.
5.2.4.7 Mechanical cycle test at the selected test temperature (test 4)
The tests are carried out as shown below.
a) Perform mechanical cycles at the selected test temperature while the test valve is kept pressurized.
b) Measure the leakage from the stem (or shaft) seal only in accordance with Annex A.
c) Record the test result in a test report.
d) Repeat the test in case of Class CO1 and CC1, as indicated in Figures 4 and 6.
5.2.4.8 Intermediate static test at the room temperature (test 5)
The tests are carried out as shown below.
a) Allow a test valve to return to the room temperature, without artificial cooling (or heating).
b) After the valve temperature has been stabilized, measure the leakage from the stem (or shaft) seal
only in accordance with Annex A.
c) Record the test result in a test report.
5.2.4.9 Final test at the room temperature (test 6)
The tests are carried out as shown below.
a) Allow a test valve to return to the room temperature, without artificial measures.
b) After the valve temperature has been stabilized, measure the leakage from the stem (or shaft) seal
in accordance with Annex A and from body seals in accordance with Annex B.
c) Record the test results in the test report.
10 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

5.2.4.10 Post-test examination
After all the tests have been successfully completed, the test valve shall be disassembled and all sealing
components shall be visually examined to record notable wear and any other significant observations
for information.
5.2.4.11 Qualification
Tested valves shall be qualified when
— all steps of test procedures have been satisfactorily performed for the target performance class, and
— all leakage measurements are verified equal or lower than the values specified for the target
performance class.
6 Performance classes
6.1 Classification criteria
Valve operating conditions and hazards of the line fluid being handled can result in different levels of
valve emission performance.
The purpose of Clause 6 is to define classification criteria resulting from the type test.
A performance class is defined by the combination of the following criteria:
a) “tightness class”: see Tables 1 and 2 (helium as test fluid), Tables 3 and 4 (methane as test fluid);
b) “endurance class”: see Figures 4, 5, and 6;
c) “temperature class”: see Table 5.
6.2 Tightness classes
6.2.1 Definition
Tightness classes are defined only for stem (or shaft) sealing systems.
Table 1 — Tightness classes for stem (or shaft) seals with helium
Measured leak Measured leak Measured leak rate
rate (mass flow) rate (mass flow) (volumic flow)
?1
mbar?l?s per mm
Class Remarks
?1 ?1 ?1 ?1
mg·s ·m stem mg·s ·mm stem
stem diameter
perimeter diameter through
through stem seal
(for information) stem seal system
system
Typically achieved with bellow seals
a ?5 ?8 ?7
AH ≤10 ≤3,14?10 ≤1,78?10 or equivalent stem (shaft) sealing
system for quarter turn valves
Typically achieved with PTFE based
b ?4 ?7 ?6
BH ≤10 ≤3,14?10 ≤1,78?10
packings or elastomeric seals
Typically achieved with flexible
b ?2 ?5 ?4
CH ≤10 ≤3,14?10 ≤1,78?10
graphite based packings
a
Measured by the vacuum method as defined in Annex A.
b
Measured by the total leak rate measurement method (vacuum or bagging) as defined in Annex A.
? ISO 2015 – All rights reserved 11BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Table 2 — Leakage from body seals with helium
Measured leakage
ppmv
≤50
NOTE Measured by the sniffing method as defined in
Annex B.
Table 3 — Tightness classes for stem (or shaft) seals with methane
Class Measured leakage (sniffing
method as described in Annex B)
ppmv
AM ≤50
BM ≤100
CM ≤500
Table 4 — Leakage from body seals with methane
Measured leakage (sniffing method as described in
Annex B)
ppmv
≤50
6.2.2 Helium as test fluid
When the test fluid is helium, the tightness classes are identified as Class AH, Class BH, and Class CH.
6.2.3 Methane as test fluid
When the test fluid is methane, the tightness classes are identified as Class AM, Class BM, and Class CM.
6.2.4 Correlations
There is no correlation intended between measurements of total leak rate as described in Annex A and
local sniffed concentration as described in Annex B.
There is no correlation intended between the tightness classes when the test fluid is helium (Class AH,
Class BH, and Class CH) and when the test fluid is methane (Class AM, Class BM, and Class CM).
6.3 Endurance classes
6.3.1 Mechanical-cycle classes for isolating valves
The required minimum number of mechanical cycles for isolating valves shall be 205 cycles (full stroke)
with two thermal cycles (a total of 50 cycles at RT, 50 cycles at test temperature, 50 cycles at RT, 50 cycles
at test temperature and 5 cycles at RT). This classification stage shall be identified as CO1 (see Figure 4).
An extension to classification CO2 shall be accomplished by addition of 1 295 mechanical cycles with
one thermal cycle (795 cycles at RT followed by 500 cycles at test temperature). Further extension to
CO3, etc. shall be achieved by addition of 1 000 mechanical cycles with one thermal cycle (see Figure 5).
12 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Key
T test temperature, °C
test
L measurement of leakage of stem seal
1
L measurement of leakage of body seal
2
N number of mechanical cycles
P test fluid pressure
NOTE The numbers 1 to 6 refer to the test sequences test 1 to test 6 as defined in 5.2.4.4 to 5.2.4.9.
Figure 4 — Mechanical-cycle classes for isolating valves (endurance Class CO1)
? ISO 2015 – All rights reserved 13BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Key
T test temperature, °C
test
L measurement of leakage of stem seal
1
L measurement of leakage of body seal
2
N number of mechanical cycles
P test fluid pressure
NOTE The numbers 1 to 6 refer to the test sequences test 1 to test 6 as defined in 5.2.4.4 to 5.2.4.9.
Figure 5 — Mechanical-cycle classes for isolating valves (endurance Classes CO2 and CO3)
6.3.2 Mechanical-cycle classes for control valves
The required minimum number of mechanical cycles for control valves shall be 20 000 cycles having two
thermal cycles (a total of 10 000 cycles at RT and 10 000 cycles at test temperature). This classification
stage shall be identified as CC1. An extension to classification CC2 shall be accomplished by addition
of 40 000 mechanical cycles having one thermal cycle (a total of 20 000 cycles at RT followed by
20 000 cycles at test temperature). Further extension to CC3 etc. shall be achieved by repetition of the
requirement for CC2 (see Figure 6).
14 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Key
T test temperature, °C
test
L measurement of leakage of stem seal
1
L measurement of leakage of body seal
2
N number of mechanical cycles
P test fluid pressure
NOTE The numbers 1 to 6 refer to the test sequences test 1 to test 6 as defined in 5.2.4.4 to 5.2.4.9.
Figure 6 — Mechanical-cycle classes for control valves
6.4 Temperature classes
The target temperature class shall be selected from Table 5. If the test is carried out at any temperature
other than those specified in Table 5, the next lower class shall apply in case of the test temperature
being above zero, or the next higher class shall apply in case of the test temperature being below zero.
EXAMPLE If the test temperature is 405 °C, the value shall be classified as (t400 °C).
Table 5 — Temperature classes
(t-196 °C) (t-46 °C) (tRT) (t200 °C) (t400 °C)
?196 °C ?46 °C Room temperature, °C 200 °C 400 °C
All test temperatures shall be recorded in the test report.
— Test at ?196 °C qualifies the valve in the range ?196 °C up to RT.
— Test at ?46 °C qualifies the valve in the range ?46 °C up to RT.
— Test at RT qualifies the valve in the range ?29 °C to +40 °C.
— Test at 200 °C qualifies the valve in the range RT up to 200 °C.
? ISO 2015 – All rights reserved 15BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

— Test at 400 °C qualifies the valve in the range RT up to 400 °C.
To qualify a valve in the range ?46 °C up to 200 °C, two tests are necessary:
— The test at ?46 °C qualifies the valve in the range ?46 °C up to RT;
— The test at 200 °C qualifies the valve in the range RT up to 200 °C.
Alternative temperature classes shall be subject to the agreement between the manufacturer and the
purchaser.
6.5 Examples of class designation
— tightness class: B (reference in Table 1)
— endurance class:
— isolating valve CO1 (reference in Figure 4);
— control valve CC1 (reference in Figure 6).
— temperature class: a test at t200 °C and a test at t?46 °C
— test pressure: according to PN or ANSI class rating depending on a relevant valve standard or
in bar at room temperature and at test temperature for specific tests; the standard reference is
ISO 15848-1
— number of stem seal adjustments (SSA): 1
6.6 Marking
In addition to the marking required by relevant standards, production valves qualified by type testing
in accordance with this part of ISO 15848 can be marked with “ISO FE”, which stands for ISO fugitive
emission, and the information as indicated in 6.5.
EXAMPLE 1 Performance class: ISO FE BH (or BM) — CO1 — SSA 1 — t(?46°C, 200 °C) — PN 16 — ISO 15848-1.
EXAMPLE 2 Performance class: ISO FE BH (or BM) — CO1 — SSA 1 — t(?46°C, 200 °C) — CL150 — ISO 15848-1.
EXAMPLE 3 In case of specific tests in bars:
Performance class: ISO FE BH (or BM) — CO1 — SSA 1 — t200 °C — (40/30) — ISO 15848-1.
7 Reporting
The test report shall include the following information:
a) name and address of the valve manufacturer;
b) valve sizes and pressure class;
c) valve model number and style;
d) method of sample selection;
e) diagram of the test rig and the data of the test equipment, including the detector make and model or
the probe flow rate where any sniffing measurement is quoted;
f) date of test;
g) reference standards with applicable revision numbers;
h) test fluid;
16 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

i) valve performance classes achieved;
j) valve mounting instructions;
k) valve repacking before type test to be reported, if applicable;
l) insulation of test valve to be reported, if applicable;
m) valve operation data:
— valve operating torque or force;
— gland bolt tightening torque;
— stroke/angle;
n) description of the actuator, if applicable;
o) copy of the test sequence;
p) detailed results of the test;
q) qualification certificate: the certificate shall indicate the number of the standard and its year of
issue (e.g. ISO 15848-1:2015).
The specific product data file including the following information shall be the responsibility of the
manufacturer and shall be included as an annex:
a) cross sectional valve assembly drawing;
b) bill of valve materials;
c) stem or shaft seal description, dimensions, and specifications;
d) body seal(s) description, dimensions, and specifications;
e) material specifications of stem (or shaft) seal components;
f) hydrostatic test certificate.
8 Extension of qualification to untested valves
Upon the successful completion of the test program as defined in this part of ISO 15848, this qualification
can be extended to untested sizes and classes of valves of the same type, if the following criteria are met:
a) the stem (or shaft) seals and body seals are of the same material, design (shape), and construction,
independent of the size;
b) loading arrangement applies a similar sealing stress to the seal element as that applied in the test
valve;
c) the type of motion of the stem (or shaft) is identical;
d) tolerances classes and surface finishes specifications of all valve components which affect sealing
performance are identical;
NOTE The tolerances classes are in accordance with ISO 286-1 and ISO 286-2.
e) stem diameters are from half to twice the tested valve diameter, half diameter and double diameter
included: D /2 ≤ D ≤ 2 D with D being the stem diameter of the tested valve;
o o o
f) the valve class or PN designation is equal or lower;
? ISO 2015 – All rights reserved 17BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

g) the required temperature class falls between the room temperature and the test temperature of the
qualified valve;
h) the tightness class required is equal to, or less severe than that of the qualified valve.
The use of gearbox or other actuator does not require separated qualification, provided above criteria
are met.
18 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Annex A
(normative)

Total leak rate measurement
A.1 Vacuum method (helium only)
A.1.1 General
This Clause specifies the vacuum method used to measure the total leak rate of the stem sealing system
of an industrial valve in using a helium mass spectrometer.
The test fluid is helium (97 % purity).
A.1.2 Principle
The principle of the vacuum method is illustrated in Figure A.1. The leakage source is enclosed in a tight
chamber, which is evacuated and then connected to the helium mass spectrometer.
The tight chamber may be fulfilled by the design of the stem sealing system.
Key
1 vacuum chamber
2 pressurized helium
3 vacuum helium detector
Figure A.1 — Principle of the vacuum method
A.1.3 Equipment and definitions
A.1.3.1 Helium mass spectrometer
The helium mass spectrometer type and main characteristics shall be specified.
? ISO 2015 – All rights reserved 19BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

The sensitivity of the helium mass spectrometer shall be in accordance with the range of the leak rate
to be measured.
The helium mass spectrometer measurement corresponds to the rate at which a volume of helium at
3 ?1
specified pressure passes a given cross section of the test system (SI unit: Pa?m ?s ).
Then, the leak rate is reported to the outer stem diameter (see A.1.7).
?9 ?1
As regards the helium systems, the instrument shall have sensitivity at least 1?10 ?mbar?l?s for helium.
The response time of the helium mass spectrometer is evaluated (or verified) by using the standard
calibrated leak. The time is recorded when the standard calibrated leak is opened to the helium mass
spectrometer and when the increase in helium mass spectrometer output signal becomes stable.
The elapse time between the helium application and the moment where the reading represents 90 % of
the equilibrium signal is the response time of the helium mass spectrometer.
A.1.3.2 Auxiliary pump system
The size of the tested valve can necessitate the use of an auxiliary vacuum pump system. Then the
ultimate absolute pressure and pump speed capability shall be sufficient to attain required test
sensitivity and response time.
A.1.3.3 Helium pressurization
It shall be possible to apply helium pressure up to the nominal test pressure of the valve.
A.1.3.4 Standard calibrated leak
In order to evaluate the response time of the whole measuring system, the standard calibrated leak
connection should be placed on the vacuum enclosure as near as possible to the stem sealing system.
The standard calibrated leak may be either of a permeation or a capillary type. The standard calibrated
leak shall be selected depending on the tightness class of the tested valve. Depending on the helium
mass spectrometer manufacturer, different standard calibrated leaks exist for one item of equipment:
— a permeation type leak standard, which shall be a calibrated permeation type leak through fused
?6 3
glass or quartz. The standard shall have a helium leakage rate in the range of 1 × 10 atm?cm /s to
?10 3 ?7 3 ?11 3
1 × 10 atm?cm /s (1 × 10 Pa?m /s to 1 × 10 Pa?m /s);
— a capillary type leak standard, which shall be a calibrated capillary type leak through a tube. The
standard shall have a leakage rate equal to or smaller than the required test sensitivity times the
actual percent test concentration of the selected tracer gas.
A.1.4 Calibration
A.1.4.1 Helium mass spectrometer
A.1.4.1.1 Warm up
The instrument shall be turned on and allowed to warm up for the minimum time specified by the
manufacturer of the instrument prior to calibrating with the calibrated leak standard.
A.1.4.1.2 Calibration
The instrument shall be calibrated as specified by the manufacturer of the instrument using permeation
or a capillary type standard.
20 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

The helium mass spectrometer shall be calibrated
— at the beginning of each test and routinely if the test takes a long time (e.g. calibration once a week),
and
— over the tightness class range required.
A.1.4.2 System calibration
A standard calibrated leak with 100 % helium shall be attached, where possible, to the component as far
as possible from the instrument connection to the component (Figure A.2).
The instrument shall be turned on and allowed to warm up for the minimum time specified by the
manufacturer of the instrument prior to calibrating with the standard calibrated leak. The standard
calibrated leak shall remain open during system calibration until the response time has been determined.
a) Evacuation: with the component evacuated to an absolute pressure sufficient for connection of the
helium mass spectrometer to the system, the standard calibrated leak shall remain open during
system calibration until the response time has been determined.
b) Response time of the full system: the time is recorded when the standard calibrated leak is opened
to the system and when the increase in helium mass spectrometer output signal becomes stable. The
elapse time between the helium application and the moment where the reading represents 90 % of
the equilibrium signal is the response time of the system. Calibration measurement duration shall
be approximately two times the instrument response time.
c) Background reading: background is established after determining response time. The standard
calibrated leak is closed to the system and the instrument reading shall be recorded when it becomes
stable.
A.1.5 Requirements for the test
A.1.5.1 Tight chamber
The tight chamber shall be tight enough to enhance the establishment of a vacuum warranting the
measurement accuracy.
The tight chamber shall be so sized as to allow the valve actuator to be moved. During heating, the
inside of the tight chamber should be ventilated, or the tight chamber can be removed to stabilize the
temperature and avoid any overheating of the valve body that is not representative of real operating
conditions.
A.1.5.2 Instrumented stem sealing system
It shall meet the same tightness requirements as the tight chamber.
In addition, the operator shall check that
— the vacuum tap is correctly positioned for leak rate measurement, and
— the vacuum tap remains unclogged throughout the test.
In addition, the sealing of instrumented stem sealing system shall withstand the temperature and
mechanical cycling conditions required during testing (durability conditions).
While the stem sealing system is being instrumented, the modifications made on the gland shall maintain
operating conditions representative of the real valve stem operation.
? ISO 2015 – All rights reserved 21BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

A.1.5.3 Pollution and packing degradation
Provision shall be made for a filter to protect the helium mass spectrometer against any pollution, which
might result from packing degradation products and make the leak measurement erroneous.
It is also recommended to properly establish a vacuum within the spectrometer prior to any measurement,
so that to ensure the absence of any pollution and possibly eliminate it.
A.1.5.4 Safety
All accessories used to contain pressure in the valve body (flanges, bolting, all fittings, etc.) shall be
suitable for test pressure and temperature.
The valve to be tested shall be carefully fastened before pressurization and cycling.
The pressure inside the valve body shall be increased slowly.
A.1.5.5 Personnel qualification
This method shall be applied by qualified and suitably trained operators.
A.1.6 Testing procedure
A.1.6.1 Test set-up
The test set-up is shown schematically in Figure A.2.
Key
1 helium at 97 % purity 6 standard calibrated leak
2 pressure control 7 vacuum breaker (optional)
3 actuator 8 tested stem sealing
4 vacuum 9 helium mass spectrometer
5 helium 10 data acquisition
Figure A.2 — Equipment
A.1.6.2 Preparation of the tested valve
Before each test
— the valve is cleaned and dried, and
22 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

— the packing tightening checked.
The hydrostatic test shall be performed before testing the valve in high pressure and high temperature
conditions.
After the hydrostatic test, the packing shall be dry before any sealing test (when using packing in the
stem sealing system). It is recommended that the packing is replaced.
If the tight chamber encloses the entire valve, connection flanges shall be welded to avoid any leaks that
come from them. In this case, the measurements correspond to the leaks from stem sealing system and
body seals.
A.1.6.3 Calibration
See A.1.4.
A.1.6.4 Measurement
The measurement is carried out as follows:
a) establishment of a vacuum inside the tight chamber and connection of the helium mass spectrometer
to the tight chamber;
b) determination of the system response time (e.g. by use of a calibrated leak as shown in Figure A.2);
c) helium background levels recording;
d) valve pressurization;
e) test temperature stabilization;
f) leak recording;
g) leak stabilization (see Figure A.3);
h) leak measurement.
? ISO 2015 – All rights reserved 23BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Key
L leak rate, in milligrams per second per metre
L leakage 1
1
L leakage 2
2
T time, in seconds
t stabilization time t
1 1
t stabilization time t
2 2
Figure A.3 — Examples of stabilization times for leaks measured using the global method
A.1.7 Leak rate calculation
The vacuum method allows the measurement of the total (global) leak rate of the stem sealing system.
The measurement L is expressed in millibars litre per second.
v
The mass flow rate, L , expressed in milligrams per second, is calculated from L by the following
m v
formula:
LL =× 0,164 (A.1)
m v
from EN 1779:1999, Annex B, at 298 °K.
Then the leak rate, L , expressed in milligrams per second per millimetre stem outside diameter, is
mm
calculated from L by the following formula:
m
L
m
L = (A.2)
mm
OD
stem
where
OD is the stem outside diameter, expressed in millimetres.
stem
A.2 Bagging method (helium only)
A.2.1 General
This Clause specifies the bagging method used to measure the total leak rate of the stem sealing system
of an industrial valve using a helium mass spectrometer.
24 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

The test fluid is helium (97 % purity).
Two methods can be used to measure the leak rate of the stem sealing system by bagging:
— the accumulation method as described in EN 13185:2001, 10.4;
— the “Suck Through Method” as described in Reference [14] and below.
A.2.2 Principle (“Suck Through Method”)
The principle of the “Suck Through Method” is illustrated in Figure A.4. The leakage source is enclosed
by a bagged volume. This volume, or bag, is connected to helium mass spectrometer through a constant
flow rate detector probe (sniffer). The extracted volume is replenished through a balancing tube with
a length at least 50 times the probe inside diameter, connected to atmosphere. Air passes through the
bag, where it mixes with the leakage stream of the test gas. Then, it passes down the sniffer probe to the
instrument detector. All leaked test gas passes through the helium mass spectrometer.
Key
1 bagged volume
2 pressurized helium
3 helium detector
4 balancing tube
Figure A.4 — Principle of the bagging method (Suck Through Method)
A.2.3 Equipment and definitions
A.2.3.1 Helium mass spectrometer
The helium mass spectrometer type and main characteristics shall be specified.
The sensitivity of the helium mass spectrometer shall be in accordance with the range of the leak rate
to be measured.
The helium mass spectrometer measurement corresponds to the rate at which a volume of helium at
specified pressure passes a given cross section of the test system.
Then, the leak rate is reported to the stem outside diameter (see A.2.7).
? ISO 2015 – All rights reserved 25BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

?9 ?1
As regards the helium systems, the instrument shall have a sensitivity of at least 1?10 mbar?l?s . When
?7 ?1
using the bagging method with a sniffer, the sensitivity shall be at least 1?10 mbar?l?s .
The response time of the helium mass spectrometer is evaluated (or verified) in using the standard
calibrated leak. The time is recorded when the standard calibrated leak is opened to the helium mass
spectrometer and when the increase in helium mass spectrometer output signal becomes stable.
The elapse time between the helium application and the moment where the reading represents 90 % of
the equilibrium signal is the response time of the helium mass spectrometer.
A.2.3.2 Bagged volume
The stem sealing system is as presented in Figure A.5.
Key
1 valve stem
2 valve body
3 bagged volume
4 to detector
Figure A.5 — Sealed volume
The hypothesis is that the concentration level found by the detector is representative of the concentration
throughout the volume VO.
A preliminary measurement with a standard leak in the volume VO allows to verify this hypothesis and
to estimate the system response time (time required to obtain a stable signal that corresponds at least
to 90 % of the leak).
The increased concentration of the tracer gas is the balance of inflow and outflows collected by the
detector (neglecting leakage of bagging).
The concentration C in the bag is measured continuously up to stabilization C .
∞
26 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Based on Reference [14], the calculated Q is expressed by the following formula:
l
() CC ?× Q
∞ f
p
Q = (A.3)
l
1 ?C
()
f
where
C is the concentration in the bag;
C is the stabilized C versus time;
∞
C is the concentration of the inflow;
f
Q is the inflow rate;
f
Q is the leakage flow rate;
l
Q is the flow rate of the pump of the helium mass spectrometer.
p
A graphical presentation of C is given in Figure A.6.
∞
Key
?1
1 reading of the helium mass spectrometer, in millibar litre per second (mbar?l?s )
2 time, in second (s)
Figure A.6 — Graphical representation of reading
3 ?1
If C is negligible (typical concentration of helium in the air) and the flow probe, Q , is equal to 1 cm ?s ,
f p
the reading of the helium mass spectrometer is close to the leak rate, Q .
l
? ISO 2015 – All rights reserved 27BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

A.2.4 Calibration
A.2.4.1 Helium mass spectrometer
A.2.4.1.1 Warm up
The instrument shall be turned on and allowed to warm up for the minimum time specified by the
manufacturer of the instrument prior to calibrating with the calibrated leak standard.
A.2.4.1.2 Calibration of the helium mass spectrometer
The instrument shall be calibrated as specified by the manufacturer of the instrument using permeation
or a capillary type standard.
The helium mass spectrometer shall be calibrated
— at the beginning of each test and routinely if the test takes a long time (e.g. calibration once a week),
and
— over the tightness class range required.
A.2.4.2 System calibration
A standard calibrated leak with 100 % helium shall be attached, where possible, to the component as far
as possible from the instrument connection to the component (Figure A.7).
The instrument shall be turned on and allowed to warm up for the minimum time specified by the
manufacturer of the instrument prior to calibrating with the standard calibrated leak.
a) The valve stem shall be positioned such that the bag is at its maximum contained volume and at its
maximum length. The standard calibrated leak shall remain open during system calibration until
the response time has been determined.
b) Response time of the full system: the time is recorded when the standard calibrated leak is opened
to the system and when the increase in helium mass spectrometer output signal becomes stable. The
elapse time between the helium application and the moment where the reading represents 90 % of
the equilibrium signal is the response time of the system. Calibration measurement duration shall
be approximately two times the instrument response time.
c) Background reading: background is established after determining response time. The standard
calibrated leak is closed to the system and the instrument reading shall be recorded when it becomes
stable.
A.2.5 Requirements for the test
A.2.5.1 Sealed volume
The sealed volume, or bag, shall be tight enough and fitted with a balancing tube long enough to ensure
all leakage is collected warranting the measurement accuracy.
The bag shall be sized and attached, so that to allow the valve actuator to be moved.
To replenish the extracted volume by the sniffer probe, a balancing tube of at least 50 probe-diameter-
length is connected to the bag, with the inlet connected to open air.
A.2.5.2 Instrumented stem sealing system
Piping, tubing, and hose connections between the sniffer probe and helium mass spectrometer shall be
capable of sealing against internal vacuum.
28 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Pick up and record the test temperature before the measurement.
In addition, the sealing of instrumented stem sealing system shall withstand the temperature and
mechanical cycling conditions required during testing (durability conditions).
While the stem sealing system is being instrumented, the modifications made on the gland shall maintain
operating conditions representative of the real valve stem operation.
A.2.5.3 Pollution and packing degradation
Provision shall be made for a filter to protect the helium mass spectrometer against any pollution, which
might result from packing degradation products, and make the leak measurement erroneous.
A.2.5.4 Safety
All accessories used to contain pressure in the valve body (flanges, bolting, all fittings, etc.) shall be
suitable for test pressure and temperature.
The valve to be tested shall be carefully fastened before pressurization and cycling. The pressure inside
the valve body shall be increased slowly.
A.2.5.5 Personnel qualification
This method shall be applied by qualified and suitably trained operators.
A.2.6 Testing procedure
A.2.6.1 Test set-up
The test set-up is shown schematically in Figure A.7.
Key
1 helium at 97 % purity 5 helium
2 pressure control 6 standard calibrated leak
3 actuator 7 helium mass spectrometer
4 sealed volume or bag 8 data acquisition
Figure A.7 — Equipment
A.2.6.2 Preparation of the tested valve
Before each test
— the valve is cleaned and dried, and
? ISO 2015 – All rights reserved 29BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

— the packing tightening checked.
The hydrostatic test shall be performed before testing the valve in high pressure and high temperature
conditions.
After the hydrostatic test, the packing shall be dry before any sealing test (when using packing in the
stem sealing system). It is recommended that the packing is replaced.
A.2.6.3 Calibration
See A.2.4.
A.2.6.4 Measurement
The measurement is carried out as follows:
a) establishment of a pressure-balanced sealed volume and connection of the helium mass spectrometer
probe to the sealed volume;
b) determination of the system response time in accordance with A.2.4.2 (e.g. by use of a calibrated
leak as shown in Figure A.7);
c) helium background levels recording;
d) valve pressurization;
e) test temperature stabilization;
f) leak recording;
g) waiting for leak stabilization (Figure A.6);
h) leak measurement.
A.2.7 Leak rate calculation
The bagging method allows the measurement of the total (global) leak rate of the stem sealing system.
?1
The measurement L , is expressed in millibars litre per second (mbar?l?s ).
v
The leak rate, L , expressed in millibars litre per second per millimetre stem outside diameter
vm
?1 ?1
(mbar?l?s ?mm ), is calculated from L by the following formula:
v
L
v
L = (A.4)
vm
OD
stem
where
OD is the the stem outside diameter, expressed in millimetres.
stem
If required, the mass flow rate, L , expressed in milligrams per second, is calculated from L by the
m v
following formula:
LL =× 0,164 (A.5)
mv
from EN 1779:1999, Annex B, at 298 °K.
30 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Then the leak rate, L , expressed in milligrams per second per millimetre stem outside diameter, is
mm
calculated from L by the following formula:
m
L
m
L = (A.6)
mm
OD
stem
where
OD is the stem outside diameter, expressed in millimetres.
stem
? ISO 2015 – All rights reserved 31BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Annex B
(normative)

Leak measurement using the sniffing method
B.1 Helium as test fluid
B.1.1 General
This Clause specifies the use of a helium leak detector, fitted with a detector probe (sniffer), to measure
helium concentration due to emissions from stem sealing systems and body seals.
The test fluid is helium.
T h e m e a s u r e m e n t s a r e m a d e a c c o r d i n g t o t h e p r i n c i p l e d e s c r i b e d i n E PA p r o c e d u 2r1e (s e e R e f e r e n c e [15]).
B.1.2 Terms and definitions
For the purposes of this Clause, the following terms and definitions apply.
B.1.2.1
leak definition concentration
local helium concentration at the surface of a leak source that indicates that a leak is present
B.1.2.2
calibration gas
concentration approximately equal to the leak definition concentration
B.1.2.3
no-detectable emission
any helium concentration at a potential leak source (adjusted for local helium ambient concentration)
that is less than a value corresponding to the instrument readability specification of B.1.4.1.1 and
which indicates that a leak is not present
B.1.2.4
calibration precision
degree of agreement between measurements of the same known value, expressed as the relative
percentage of the average difference between the meter readings and the known concentration to the
known concentration
B.1.2.5
response time
time interval from a step change in helium concentration at the input of the sampling system to the
time at which 90 % of the corresponding final value is reached as displayed on the instrument readout
master
B.1.3 Principle
A portable instrument is used to detect leaks from valves. The instrument detector type is not specified,
but the selected detector and its sensitivity shall be able to meet the tightness class limits. This procedure
is intended to locate and classify leaks only, and is not used as a direct measure of mass emission rates
from individual sources.
The detector probe (sniffing) method, see Figure B.1 and Figure B.2, allows the measurement of the
local emission of the stem sealing system and body seals.
32 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

The measured concentration can be expressed in parts per million volume (ppmv).
Key
1 valve stem
2 probe
Figure B.1 — Local measurement sniffing
Key
1 helium gas supply 5 mass spectrometer
2 vent QC quick coupling
3 pressure recorder RV relief valve
4 probe PI pressure sensor
Figure B.2 — Local measurement by sniffing method
? ISO 2015 – All rights reserved 33BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

B.1.4 Apparatus
B.1.4.1 Monitoring instrument
B.1.4.1.1 Specifications
The helium instrument detector type may include, but is not limited to, mass spectrometry, infrared
absorption, and molecular screening.
Both the linear response range and the measurable range of the instrument shall encompass the leak
definition concentration specified in the regulation. A dilution probe assembly can be used to bring the
helium concentration within this range, however, the specification for helium sample probe diameter
shall still be met.
The scale of the instrument meter shall be readable to ±2,5 % of the specified leak definition concentration
when performing a no-detectable emission survey.
The instrument shall be equipped with an electrically driven pump to ensure that a sample is provided
?1 ?1
to the detector at a constant flow rate. The probe flow rate shall be between 0,5 l?min and 1,5 l?min .
Typical value of probe flow rate (used for this International standard) for helium mass spectrometer is
3 ?1
1 cm ?s .
The instrument shall be equipped with a probe or probe extension for sampling not to exceed 6,4 mm in
outside diameter, with a single end opening for admission of sample.
B.1.4.1.2 Performance criteria
The instrument pump, dilution probe (if any), sample probe and probe filter, which is used during
testing, shall all be in place during the response time determination.
The calibration precision shall be equal to or less than 10 % of the calibration gas value.
B.1.4.1.3 Performance evaluation requirements
The calibration precision test shall be completed prior to placing the analyser into service, and at
subsequent three-month intervals or at the next use, whichever is later.
B.1.4.2 Calibration gases
The monitoring instrument is calibrated in terms of parts per million by volume (ppmv) of helium
specified in the applicable regulation.
The calibration gases required for monitoring and instrument performance evaluation are a zero gas
(air, less than 10 ppmv helium) and a calibration gas in air mixture approximately equal to the leak
definition specified in the regulation.
3
Alternatively, the monitoring instrument can also be calibrated in terms of Pa?m /s or mbar?l/s of helium
specified in the applicable regulation. In this case, calibration leak standards can be either a permeation
or capillary type standard.
The type of leak standard used shall be established by the instrument or system sensitivity requirement,
or as specified by the applicable regulation.
— A permeation type leak standard shall be a calibrated permeation type leak through fused glass
?6 ?1
or quartz. The standard shall have a helium leakage rate in the range of 1 × 10 mbar?l?s to
?10 ?1 ?7 3 ?1 ?11 3 ?1
1 × 10 mbar?l?s (1 × 10 Pa?m ?s to 1 × 10 Pa?m ?s ).
— A capillary type leak standard shall be a calibrated capillary type leak through a tube. The standard
shall have a leakage rate equal to or smaller than the required test sensitivity times the actual
percent test concentration of the selected tracer gas.
34 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

If cylinder calibration gas mixtures are used, they shall be analysed and certified by the manufacturer to
be within ±2 % accuracy, and a shelf life shall be either reanalysed or replaced at the end of the specified
shelf life. Alternatively, calibration gases may be prepared by the user according to any accepted gaseous
standards preparation procedure that yields a mixture accurate to within ±2 %. Prepared standards
shall be replaced each day of use unless it can be demonstrated that degradation does not occur during
storage.
B.1.5 Requirements for the test
B.1.5.1 Effect of the temperature
The higher the temperature of the component, the higher the saturating vapour pressure. Consequently,
the temperature can modify the concentration measurement. This should be made in a place where the
temperature remains stable whatever the external climatic conditions.
B.1.5.2 Weather effect
The leak measurements by sniffing are particularly sensitive to variations in the gaseous atmosphere.
This is more particularly true for:
— outdoor measurements, and
— low-level measurements (see Reference [15]).
The atmosphere within the room where the leaks take place shall be calm and the openings shall remain
closed throughout the measurement.
B.1.5.3 Safety
High helium pressure levels or vacuum conditions in conjunction with high temperatures require safety
rules to be applied by operators during testing and measurement.
B.1.6 Measurements of emissions
B.1.6.1 Calibration procedures
Assemble and start up the helium analyser according to the manufacturer’s instructions. After the
appropriate warm-up period and zero internal calibration procedure, introduce the calibration gas into
the instrument sample probe. Adjust the instrument meter readout to correspond to the calibration gas
value.
The system shall be calibrated by passing the detector probe tip across the orifice of the leak standard.
The probe tip shall be kept within 3 mm of the orifice of the leak standard. The scanning rate shall not
exceed that which can detect leakage rate from the leak standard. Adjust the instrument meter readout
to correspond to the calibration gas value. The instrument meter readout shall be noted.
The time required to detect stable leakage from the leak standard is the response time and it should
be observed during system calibration. It is usually desirable to keep this time as short as possible to
reduce the time required to pinpoint detected leakage.
If the meter readout cannot be adjusted to the proper value, a malfunction of the analyser is indicated.
B.1.6.2 Measurement
Start the helium mass spectrometer as instructed by the manufacturer and electronics heating. Carry-
out the following.
a) Calibration
? ISO 2015 – All rights reserved 35BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

b) Background measurement: prior to each measurement, the ambient helium concentration around
the source is determined by moving the probe randomly at a distance of 1 m or 2 m from the source.
When there is interference in the measurement with a leak nearby, the ambient concentration can
be determined closer to the source, but the distance should in no case be smaller than 25 cm.
c) The probe is positioned as close as possible to the potential leak source, namely
— at the interface where the stem exits the packing, and
— at the outer edge of the body seals.
d) The distance of the probe to the source shall be equal to the distance used by the calibration
procedure for the analyser, not exceeding 3 mm.
e) Move the probe along the interface periphery while observing the instrument readout. The scanning
rate shall not exceed the scanning rate determined during calibration to the leak standard (which
depends on the response time, the flow rate of the pump and the probe dimension).
f) If an increased meter reading is observed, slowly sample the interface where leakage is indicated
until the maximum meter reading is obtained.
g) Leave the probe inlet at this maximum reading location for approximately two times the instrument
response time.
h) The operator reads the maximum value and records it by making the probe remain in the same
place during a period of time about twice the instrument response time (e.g. a few seconds for a 5-m
standard probe).
i) The difference between this measurement and the background noise determines whether there are
no detectable emissions.
j) Detectable emissions from emission source impose the background level to be lower than the
acceptable emission level. Background level shall be lower than 50 ppmv.
B.2 Methane as test fluid
B.2.1 General
This Clause specifies the use of a VOC instrument detector, fitted with a detector probe (sniffer), to
measure methane concentration due to emissions from stem sealing systems and body seals.
The test fluid is methane.
The measurements are made according to the principle described in EPA procedure 21 (see Reference
[15]).
B.2.2 Terms and definitions
For the purposes of this Clause, the following terms and definitions apply.
B.2.2.1
leak definition concentration
local VOC concentration at the surface of a leak source indicating that a VOC emission (leak) is present
Note 1 to entry: The leak definition is an instrument meter reading based on a reference compound.
36 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

B.2.2.2
reference compound
VOC species selected as an instrument calibration basis for specification of the leak definition concen-
tration
EXAMPLE For example, if a leak definition concentration is 500 ppmv as methane, then any source
emission that results in a local concentration that yields a meter reading of 500 ppmv on an instru-
ment calibrated with methane would be classified as a leak. In this example, the leak definition is
500 ppmv, and the reference compound is methane.
B.2.2.3
calibration gas
VOC compound used to adjust the instrument meter reading to a known value
Note 1 to entry: The calibration gas is usually the reference compound at a concentration approxi-
mately equal to the leak definition concentration.
B.2.2.4
no-detectable emission
VOC concentration at a potential leak source (adjusted for local VOC ambient concentration) that is less
than a value corresponding to the instrument readability specification of B.2.4.1.1 and which indicates
that a leak is not present
B.2.2.5
response factor
ratio of the known concentration of a VOC compound to the observed meter reading when measured
using an instrument calibrated with the reference compound specified in the application regulation
B.2.2.6
calibration precision
degree of agreement between measurements of the same known value, expressed as the relative
percentage of the average difference between the meter readings and the known concentration to the
known concentration
B.2.2.7
response time
time interval from a step change in VOC concentration at input of the sampling system to the time at
which 90 % of the corresponding final value is reached as displayed on the instrument readout meter
B.2.2.8
VOC
volatile organic compound
B.2.3 Principle
A portable instrument is used to detect VOC leaks from individual sources. The instrument detector type
is not specified, but it shall meet the specifications and performance criteria contained in B.2.4.1.2. A
leak definition concentration based on a reference compound is specified in each applicable regulation.
This procedure is intended to locate and classify leaks only and shall not be used as a direct measure of
mass emission rates from individual sources.
The detector probe (sniffing) method allows the measurement of the local emission of the stem sealing
system (production test) and body seals, see Figure B.2.
The measured concentration is expressed in parts per million volume (ppmv).
? ISO 2015 – All rights reserved 37BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

B.2.4 Apparatus
B.2.4.1 Monitoring instrument
B.2.4.1.1 Specifications
The VOC instrument detector shall respond to the compounds being processed. Detector types which
meet this requirement include, but are not limited to, catalytic oxidation, flame ionization, infrared
absorption, and photo ionization.
Both the linear response range and the measurable range of the instrument for each of the VOC to
be measured, and for the VOC calibration gas that is used for calibration, shall encompass the leak
definition concentration specified in the regulation. A dilution probe assembly may be used to bring the
VOC concentration within both ranges. However, the specifications for instrument response time and
sample probe diameter shall still be met.
The scale of the instrument meter shall be readable to ±2,5 % of the specified leak definition concentration
when performing a no-detectable emission survey.
The instrument shall be equipped with an electrically driven pump to ensure that a sample is provided
to the detector at a constant flow rate. The nominal sample flow rate, as measured at the sample probe
?1 ?1
tip, shall be 0,10 l?min to 3,0 l?min when the probe is fitted with a glass wool plug or filter that can be
used to prevent plugging of the instrument.
The instrument shall be intrinsically safe as designed by the applicable US standards (e.g. National
Electric Code by the National Fire Prevention Association) for operation in any explosive atmospheres
that can be encountered in its use. The instrument shall not be operated with any safety device, such as
an exhaust flame arrestor.
NOTE The instrument is intrinsically safe for Class 1, division 1 conditions, and Class 2, division 1 conditions,
as defined by the National Electric Code.
The instrument shall be equipped with a probe or probe extension for sampling not to exceed 6,4 mm in
outside diameter, with a single end opening for admission of sample.
B.2.4.1.2 Performance criteria
The instrument response factors for each of the VOC to be measured shall be less than 10. When no
instrument is available that meets this specification when calibrated with the reference VOC specified
in the applicable regulation, the available instrument may be calibrated with one of the VOC to be
measured, or any other VOC, so long as the instrument then has a response factor of less than 10 for
each of the VOC to be measured.
The instrument response time shall be equal to or less than 30 s. The instrument pump, dilution probe
(if any), sample probe and probe filter, which is used during testing, shall all be in place during the
response time determination.
B.2.4.1.3 Performance evaluation requirements
A response factor shall be determined for each compound to be measured, either by testing or from
reference sources. The response factor tests are required before placing the analyser into service, but
do not have to be repeated at subsequent intervals.
The calibration precision test shall be completed prior to placing the analyser into service, and at
subsequent three-month intervals or at the next use, whichever is later.
The response time test is required prior to placing the instrument into service. If a modification to the
sample pumping system or flow configuration is made that would change the response time, a new test
is required prior to further use.
38 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

B.2.4.2 Calibration gases
The monitoring instrument is calibrated in terms of parts per million by volume (ppmv) of the reference
compound specified in the applicable regulation.
The calibration gases required for monitoring and instrument performance evaluation are a zero gas (air,
less than 10 ppmv VOC) and a calibration gas in air mixture approximately equal to the leak definition
specified in the regulation.
If cylinder calibration gas mixtures are used, they shall be analysed and certified by the manufacturer to
be within ±2 % accuracy, and a shelf life shall be specified. Cylinder standards shall be either reanalysed
or replaced at the end of the specified shelf life.
Alternatively, calibration gases can be prepared by the user according to any accepted gaseous standards
preparation procedure that yields a mixture accurate to within ±2 %. Prepared standards shall be
replaced each day of use, unless it can be demonstrated that degradation does not occur during storage.
Calibrations can be performed using a compound other than the reference compound if a conversion
factor is determined for that alternative compound, so that the resulting meter readings during source
surveys can be converted to reference compound results.
B.2.5 Requirements for the test
B.2.5.1 Effect of the temperature
The higher the temperature of the component, the higher the saturating vapour pressure. Consequently,
the temperature can modify the concentration measurement. This should be made in a place where the
temperature remains stable whatever the external climatic conditions.
B.2.5.2 Weather effect
The leak measurements by sniffing are particularly sensitive to variations in the gaseous atmosphere.
This is more particularly true for
— outdoor measurements, and
— low-level measurements (see Reference [15]).
The atmosphere within the room where the leaks take place shall be calm and the openings shall remain
closed throughout the measurement.
B.2.5.3 Safety
High methane pressure levels in conjunction with high temperatures require safety rules to be applied
by operators during testing and measurement.
B.2.6 Measurements
B.2.6.1 Calibration
The instrument shall be calibrated as specified by the manufacturer of the instrument.
B.2.6.2 Measurement
Start the VOC instrument detector as instructed by the manufacturer and electronics heating. Carry-out
the following.
a) Instrument detection calibration.
b) Background noise measurement: prior to each measurement, the ambient methane concentration
around the source is determined by moving the probe randomly at a distance of one (or two) meter(s)
? ISO 2015 – All rights reserved 39BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

from the source. When there is interference in the measurement with a leak nearby, the ambient
concentration can be determined closer to the source, but the distance should in no case be smaller
than 25 cm.
c) The probe is positioned as close as possible to the potential leak source, namely
— at the interface where the stem exits the packing, and
— at the outer edge of the body seals.
d) Move the probe along the interface periphery while observing the instrument readout.
e) If an increased meter reading is observed, slowly sample the interface where leakage is indicated
until the maximum meter reading is obtained.
f) Leave the probe inlet at this maximum reading location for approximately two times the instrument
response time.
g) The operator reads the maximum value and records it by making the probe remain in the same
place during a period of time about twice the instrument response time (e.g. a few seconds for a 5-m
standard probe).
h) The difference between this measurement and the background noise determines whether there are
no detectable emissions.
i) Detectable emissions from emission source impose the background level to be lower than the
acceptable emission level. Back ground level shall be lower than 50 ppmv.
40 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Annex C
(informative)

Leak rate conversion (helium)
C.1 Nomenclature table for leak rate conversion
The nomenclature for the leak rate conversion at a temperature of 273 °K is given in Table C.1.
Table C.1 — Nomenclature for leak rate conversion
AH BH CH
?1 ?1
L mg.s ·m per m stem perimeter 1,00 E-05 1,00 E-04 1,00 E-02
1
?1 ?1
L mg.s ·mm per mm stem diameter 3,14 E-08 3,14 E-07 3,14 E-05
2
?1 ?1
L mbar·l·s ·mm per mm stem diameter 1,78 E-07 1,78 E-06 1,78 E-04
3
C.2 Helium tightness classes evaluated from stem outside diameter
The helium tightness classes evaluated from stem outside diameter at a temperature of 273 °K are given
in Table C.2.
Table C.2 — Helium tightness classes evaluated from stem outside diameter
AH BH CH
1,00 E-05 1,78 E-07 1,00 E-04 1,78 E-06 1,00 E-02 1,78 E-04
?1 ?1 ?1 ?1 ?1 ?1 ?1 ?1 ?1 ?1 ?1 ?1
mg?s ?m mbar?l?s ?mm mg?s ?m mbar?l?s ?mm mg?s ?m per mbar?l?s ?mm
per m stem per mm stem per m stem per mm stem m stem perim- per mm stem
perimeter diameter perimeter diameter eter diameter
OD
stem
?1 ?1 ?1
Leak rate in mbar·l·s Leak rate in mbar·l·s Leak rate in mbar·l·s
mm
10 1,78 E-06 1,78 E-05 1,78 E-03
15 2,67 E-06 2,67 E-05 2,67 E-03
20 3,57 E-06 3,57 E-05 3,57 E-03
25 4,46 E-06 4,46 E-05 4,46 E-03
30 5,35 E-06 5,35 E-05 5,35 E-03
35 6,24 E-06 6,24 E-05 6,24 E-03
40 7,13 E-06 7,13 E-05 7,13 E-03
45 8,02 E-06 8,02 E-05 8,02 E-03
50 8,91 E-06 8,91 E-05 8,91 E-03
55 9,80 E-06 9,80 E-05 9,80 E-03
60 1,07 E-05 1,07 E-04 1,07 E-02
65 1,16 E-05 1,16 E-04 1,16 E-02
70 1,25 E-05 1,25 E-04 1,25 E-02
75 1,34 E-05 1,34 E-04 1,34 E-02
80 1,43 E-05 1,43 E-04 1,43 E-02
? ISO 2015 – All rights reserved 41BS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Table C.2 (continued)
AH BH CH
1,00 E-05 1,78 E-07 1,00 E-04 1,78 E-06 1,00 E-02 1,78 E-04
?1 ?1 ?1 ?1 ?1 ?1 ?1 ?1 ?1 ?1 ?1 ?1
mg?s ?m mbar?l?s ?mm mg?s ?m mbar?l?s ?mm mg?s ?m per mbar?l?s ?mm
per m stem per mm stem per m stem per mm stem m stem perim- per mm stem
perimeter diameter perimeter diameter eter diameter
90 1,60 E-05 1,60 E-04 1,60 E-02
100 1,78 E-05 1,78 E-04 1,78 E-02
110 1,96 E-05 1,96 E-04 1,96 E-02
120 2,14 E-05 2,14 E-04 2,14 E-02
130 2,32 E-05 2,32 E-04 2,32 E-02
140 2,50 E-05 2,50 E-04 2,50 E-02
150 2,67 E-05 2,67 E-04 2,67 E-02
The formulae are the following.
L ×π
1
L = (C.1)
2
1000
RT ×
L = ×× 10 L (C.2)
32
M
from EN 1779:1999, Annex B
where
?1 ?1
L is the mass flow rate, expressed in mg?s ?m ;
1
?1 ?1
L is the mass flow leak rate, expressed in mg?s ?mm ;
2
?1 ?1
L is the leak rate, expressed in mbar?l?s ?mm ;
3
R is the universal gas constant = 8,314 J per mole Kelvin;
T is the temperature, expressed in Kelvin (K);
?1
M is the molar mass, expressed in mg per mole (M = 4000 mg?mole ).
He
?2
For example, at a temperature of 273 °K, L is approximately equal to 1,78?10 L .
3 1
42 ? ISO 2015 – All rights reservedBS EN ISO 15848-1:2015
ISO 15848-1:2015(E)

Bibliography
[1] ISO 6708:1995, Pipework components — Definition and selection of DN (nominal size)
[2] ISO 7268:1983, Pipe components — Definition of nominal pressure
[3] ISO 286-1:2010, Geometrical product specifications (GPS) — ISO code system for tolerances on
linear sizes — Part 1: Basis of tolerances, deviations and fits
[4] ISO 286-2:2010, Geometrical product specifications (GPS) — ISO code system for tolerances on
linear sizes — Part 2: Tables of standard tolerance classes and limit deviations for holes and shafts
[5] EN 1779:1999, Non-destructive testing — Leak testing — Criteria for method and technique
selection
[6] ANSI/FCI 91-1:2010, Standard for Qualification of Control Valve Stem Seals
[7] ANSI/ISA-S 93.00.01:1999, Standard Method for the Evaluation of External Leakage of Manual and
Automated On-Off Valves
[8] ASME section V, Boiler and pressure vessel code; non-destructive examination, Appendix IV: Helium
mass spectrometer test — Detector probe technique, Appendix V: tracer probe and hood techniques
[9] MSS SP project 93-17 (Release 8th July 1997), Valve fugitive emission measurement and classification
[10] Clean Air Act Amendments, Updated strategies, List of air pollutants and their regulating program
[11] Environmental Protection Agency, Determination of volatile organic compound leaks, title 40,
appendix A, method 21, type 1
[12] EPA 453/R 95-017 (Release November 1995), Protocol for equipment leak emission estimates,
section 2 and appendix B, pages B7 and B18
[13] RW – TUV : TA Luft, Technische Anleitung zur reinhaltung der Luft: Aktuelle Emmissionsschutzrechtliche
Anforderungen an den Anlagenbetreiber
[14] Project S.M.T. SMT4-CT97-2158, Valve Stem Leak-Tightness Test Methodologies — EU Commission
DGXII, 25 October 2000, http://cordis.europa.eu
[15] Environmental Protection Agency, Determination of volatile organic compound leak. Code of
Federal Regulations, Title 40, Part 60, Appendix A, Reference method 21. Washington, D.C., U.S.
Government Printing Office (Revised June, 1990)
? ISO 2015 – All rights reserved 43This page deliberately left blankThis page deliberately left blankNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW
British Standards Institution (BSI)
BSI is the national body responsible for preparing British Standards and other
standards-related publications, information and services.
BSI is incorporated by Royal Charter. British Standards and other standardization
products are published by BSI Standards Limited.
About us Revisions
We bring together business, industry, government, consumers, innovators Our British Standards and other publications are updated by amendment or revision.
and others to shape their combined experience and expertise into standards
We continually improve the quality of our products and services to benefit your
-based solutions.
business. If you find an inaccuracy or ambiguity within a British Standard or other
The knowledge embodied in our standards has been carefully assembled in BSI publication please inform the Knowledge Centre.
a dependable format and refined through our open consultation process.
Copyright
Organizations of all sizes and across all sectors choose standards to help
them achieve their goals.
All the data, software and documentation set out in all British Standards and
other BSI publications are the property of and copyrighted by BSI, or some person
Information on standards
or entity that owns copyright in the information used (such as the international
We can provide you with the knowledge that your organization needs standardization bodies) and has formally licensed such information to BSI for
to succeed. Find out more about British Standards by visiting our website at commercial publication and use. Except as permitted under the Copyright, Designs
bsigroup.com/standards or contacting our Customer Services team or and Patents Act 1988 no extract may be reproduced, stored in a retrieval system
or transmitted in any form or by any means – electronic, photocopying, recording
Knowledge Centre.
or otherwise – without prior written permission from BSI. Details and advice can
Buying standards be obtained from the Copyright & Licensing Department.
You can buy and download PDF versions of BSI publications, including British
Useful Contacts:
and adopted European and international standards, through our website at
bsigroup.com/shop, where hard copies can also be purchased.
Customer Services
Tel: [phone]
If you need international and foreign standards from other Standards Development
Organizations, hard copies can be ordered from our Customer Services team. Email (orders): [e-mail]
Email (enquiries): [e-mail]
Subscriptions
Subscriptions
Our range of subscription services are designed to make using standards
Tel: [phone]
easier for you. For further information on our subscription products go to
Email: [e-mail]
bsigroup.com/subscriptions.
Knowledge Centre
With British Standards Online (BSOL) you’ll have instant access to over 55,000
British and adopted European and international standards from your desktop. Tel: [phone]
It’s available 24/7 and is refreshed daily so you’ll always be up to date.
Email: [e-mail]
You can keep in touch with standards developments and receive substantial
Copyright & Licensing
discounts on the purchase price of standards, both in single copy and subscription
Tel: [phone]
format, by becoming a BSI Subscribing Member.
Email: [e-mail]
PLUS is an updating service exclusive to BSI Subscribing Members. You will
automatically receive the latest hard copy of your standards when they’re
revised or replaced.
To find out more about becoming a BSI Subscribing Member and the benefits
of membership, please visit bsigroup.com/shop.
With a Multi-User Network Licence (MUNL) you are able to host standards
publications on your intranet. Licences can cover as few or as many users as you
wish. With updates supplied as soon as they’re available, you can be sure your
documentation is current. For further information, email [e-mail].
BSI Group Headquarters
389 Chiswick High Road London W4 4AL UK