ISO 21755-2:2020
(Main)Motorcycles — Measurement method for evaporative emissions — Part 2: Permeation test procedure
Motorcycles — Measurement method for evaporative emissions — Part 2: Permeation test procedure
This document specifies a basic measurement method by using a permeation test procedure for evaporative emissions from motorcycles. It is applicable to motorcycles equipped with a fuel tank to store liquid high volatile fuel and with a spark ignition engine (four-stroke engine, two-stroke engine or rotary piston engine).
Motocycles — Méthode de mesure pour les émissions par évaporation — Partie 2: Méthode d'essai de perméation
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INTERNATIONAL ISO
STANDARD 21755-2
First edition
2020-02
Motorcycles — Measurement method
for evaporative emissions —
Part 2:
Permeation test procedure
Motocycles — Méthode de mesure pour les émissions par
évaporation —
Partie 2: Méthode d'essai de perméation
Reference number
©
ISO 2020
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Fuel tank and fuel line assembly permeation test procedure . 1
4.1 Description of the fuel tank permeation test . 1
4.2 Test fuel . 2
4.3 Preconditioning fuel soak for the fuel tank permeation test . 2
4.4 Fuel tank permeation test procedure . 3
4.5 Fuel tank permeation test result calculation . 3
4.6 Fuel tank durability testing . 4
4.7 Fuel line assembly test requirements . 4
5 Presentation of results . 5
6 Fuel tank permeability test procedure (optional) . 5
Annex A (informative) Fuel tank permeability test procedure . 6
Annex B (normative) Presentation of the results . 8
Bibliography .10
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 of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 22, Road Vehicles, Subcommittee SC 38,
Motorcycles and mopeds.
A list of all parts in the ISO 21755 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
Introduction
This document specifies the measurement method for evaporative emissions from motorcycles
by using a permeation test procedure. However, the amount of permeation from a non-metallic fuel
tank is generally larger than that from a metallic fuel tank. Therefore, this document also specifies a
permeability test procedure in an informative annex solely for non-metallic fuel tanks as optional. This
permeability test procedure is expected to be used also by fuel tank manufacturers.
INTERNATIONAL STANDARD ISO 21755-2:2020(E)
Motorcycles — Measurement method for evaporative
emissions —
Part 2:
Permeation test procedure
1 Scope
This document specifies a basic measurement method by using a permeation test procedure for
evaporative emissions from motorcycles. It is applicable to motorcycles equipped with a fuel tank to
store liquid high volatile fuel and with a spark ignition engine (four-stroke engine, two-stroke engine or
rotary piston engine).
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
permeability
losses through the walls of the non-metallic fuel tank
3.2
permeation
losses through the walls of the fuel tank and fuel line assembly
4 Fuel tank and fuel line assembly permeation test procedure
4.1 Description of the fuel tank permeation test
4.1.1 Measure permeation emissions by weighing a sealed fuel tank before and after a temperature-
controlled soak according to the following flow charts (see Figure 1).
4.1.2 Fuel tank description shall be described in accordance with B.1.
Key
a
DF is the deterioration factor.
b
The length of "soak" during durability testing may be included in the fuel soak period provided that fuel remains
in the tank. Soak periods can be shortened to 10 weeks if performed a 316,2 K ± 5,0 K.
Figure 1 — Flow chart of fuel tank permeation full and short tests
4.2 Test fuel
The test fuel shall be selected in accordance with agreement among the parties involved or the
manufacturer's requirements and the specifications of test fuel shall be reported. An example of the
record form is given in B.2.
4.3 Preconditioning fuel soak for the fuel tank permeation test
To precondition the fuel tank in the fuel tank permeation test, the following five steps shall be followed:
4.3.1 The tank shall be filled with reference fuel specified in 4.2 and sealed. The filled tank shall be
soaked at an ambient temperature of 301,2 K ± 5,0 K for 20 weeks or at 316,2 K ± 5,0 K for 10 weeks.
4.3.2 The fuel tank’s internal surface area shall be determined in square metres accurate to at least
three significant figures. The manufacturer may use less accurate estimates of the surface area if it is
ensured that the surface area will not be overestimated.
2 © ISO 2020 – All rights reserved
4.3.3 The fuel tank shall be filled with the reference fuel to its nominal capacity.
4.3.4 The tank and fuel shall equilibrate to 301,2 K ± 5,0 K or 316,2 K ± 5,0 K in the case of the
alternative short test.
4.3.5 The fuel tank shall be sealed using fuel caps and other fittings (excluding petcocks) that can be
used to seal openings in a production fuel tank. In cases where openings are not normally sealed on the
fuel tank (such as hose-connection fittings and vents in fuel caps), these openings may be sealed using
non-permeable fittings such as metal or fluoropolymer plugs.
4.4 Fuel tank permeation test procedure
To run the test, the following steps shall be taken for a tank preconditioned as specified in 4.3.
4.4.1 Weigh the sealed fuel tank and record the weight in milligrams. This measurement shall be taken
within 8 h of filling of the tank with test fuel.
4.4.2 The tank shall be placed in a ventilated, temperature-controlled room or enclosure.
4.4.3 The test room or enclosure shall be closed and sealed and the test time shall be recorded.
4.4.4 The test room or enclosure temperature shall be continuously maintained at 301,2 K ± 5,0 K for
14 days. This temperature shall be continuously monitored and recorded.
4.5 Fuel tank permeation test result calculation
4.5.1 At the end of the soak period, the weight in milligrams of the sealed fuel tank shall be recorded.
Unless the same fuel is used in the preconditioning fuel soak and the permeation test run, weight
measurements shall be recorded on five separate days per week of testing. The test is void if a linear
plot of tank weight vs. test days for the full soak period for permeation testing yields a linear regression
correlation coefficient r < 0,8.
4.5.2 The weight of the filled fuel tank at the end of the test shall be subtracted from the weight of the
filled fuel tank at the beginning of the test.
4.5.3 The difference in mass shall be divided by the internal surface area of the fuel tank.
4.5.4 The result obtained in 4.5.3, expressed in mg/m , shall be divided by the number of test days to
calculate the (mg/m )/day emission rate and rounded to integer value.
4.5.5 In cases where permeation rates during a soak period of 14 days are not long enough to be able
to measure significant weight changes, the period may be extended by a maximum of 14 additional days.
In this case, the test steps in 4.5.2 to 4.5.4 shall be repeated to determine the weight change for the full
28 days.
4.5.6 Determination of the deterioration factor when applying the full permeation test
procedure
The deterioration factor (DF) shall be determined from any of the following choices:
— the ratio between the final permeation and baseline test runs;
— fixed DF for total hydrocarbons regulated in each country.
4.5.7 Determination of the final tank permeation test results
4.5.7.1 Full test procedure
To determine the permeation test result, the deterioration factor determined in 4.5.6 shall be multiplied
by the measured permeation test result determined in 4.5.4.
4.6 Fuel tank durability testing
4.6.1 A separate durability demonstration for each substantially different combination of treatment
approaches and fuel tank materials shall be performed by taking the following steps.
4.6.1.1 Pressure cycling
A pressure test shall be conducted by sealing the tank and cycling it between 115,1 kPa absolute
pressure and 97,9 kPa absolute pressure and back to 115,1 kPa absolute pressure for 10 000 cycles at a
rate of 60 s per cycle.
4.6.1.2 UV exposure
A sunlight exposure test shall be conducted by exposing the fuel tank to an ultraviolet light of at least
2 2
24 W/m (0,40 (W·h/m )/min) on the tank surface for at least 450 h. Alternatively, the non-metallic
fuel tank may be exposed to direct natural sunlight for an equivalent period of time, as long as it is
ensured that it is exposed to at least 450 daylight hours.
4.6.1.3 Slosh testing
A slosh test shall be conducted by filling the non-metallic fuel tank to 40 % of its capacity with the
reference fuel set out in 4.2 or with a commercial premium-grade fuel at the choice of the manufacturer.
The fuel tank assembly shall be rocked at a rate of 15 cycles per minute until 1 000 000 total cycles are
reached. An angle deviation of +15° to –15° from level shall be used
...
INTERNATIONAL ISO
STANDARD 21755-2
First edition
2020-02
Motorcycles — Measurement method
for evaporative emissions —
Part 2:
Permeation test procedure
Motocycles — Méthode de mesure pour les émissions par
évaporation —
Partie 2: Méthode d'essai de perméation
Reference number
©
ISO 2020
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Fuel tank and fuel line assembly permeation test procedure . 1
4.1 Description of the fuel tank permeation test . 1
4.2 Test fuel . 2
4.3 Preconditioning fuel soak for the fuel tank permeation test . 2
4.4 Fuel tank permeation test procedure . 3
4.5 Fuel tank permeation test result calculation . 3
4.6 Fuel tank durability testing . 4
4.7 Fuel line assembly test requirements . 4
5 Presentation of results . 5
6 Fuel tank permeability test procedure (optional) . 5
Annex A (informative) Fuel tank permeability test procedure . 6
Annex B (normative) Presentation of the results . 8
Bibliography .10
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 of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 22, Road Vehicles, Subcommittee SC 38,
Motorcycles and mopeds.
A list of all parts in the ISO 21755 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
Introduction
This document specifies the measurement method for evaporative emissions from motorcycles
by using a permeation test procedure. However, the amount of permeation from a non-metallic fuel
tank is generally larger than that from a metallic fuel tank. Therefore, this document also specifies a
permeability test procedure in an informative annex solely for non-metallic fuel tanks as optional. This
permeability test procedure is expected to be used also by fuel tank manufacturers.
INTERNATIONAL STANDARD ISO 21755-2:2020(E)
Motorcycles — Measurement method for evaporative
emissions —
Part 2:
Permeation test procedure
1 Scope
This document specifies a basic measurement method by using a permeation test procedure for
evaporative emissions from motorcycles. It is applicable to motorcycles equipped with a fuel tank to
store liquid high volatile fuel and with a spark ignition engine (four-stroke engine, two-stroke engine or
rotary piston engine).
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
permeability
losses through the walls of the non-metallic fuel tank
3.2
permeation
losses through the walls of the fuel tank and fuel line assembly
4 Fuel tank and fuel line assembly permeation test procedure
4.1 Description of the fuel tank permeation test
4.1.1 Measure permeation emissions by weighing a sealed fuel tank before and after a temperature-
controlled soak according to the following flow charts (see Figure 1).
4.1.2 Fuel tank description shall be described in accordance with B.1.
Key
a
DF is the deterioration factor.
b
The length of "soak" during durability testing may be included in the fuel soak period provided that fuel remains
in the tank. Soak periods can be shortened to 10 weeks if performed a 316,2 K ± 5,0 K.
Figure 1 — Flow chart of fuel tank permeation full and short tests
4.2 Test fuel
The test fuel shall be selected in accordance with agreement among the parties involved or the
manufacturer's requirements and the specifications of test fuel shall be reported. An example of the
record form is given in B.2.
4.3 Preconditioning fuel soak for the fuel tank permeation test
To precondition the fuel tank in the fuel tank permeation test, the following five steps shall be followed:
4.3.1 The tank shall be filled with reference fuel specified in 4.2 and sealed. The filled tank shall be
soaked at an ambient temperature of 301,2 K ± 5,0 K for 20 weeks or at 316,2 K ± 5,0 K for 10 weeks.
4.3.2 The fuel tank’s internal surface area shall be determined in square metres accurate to at least
three significant figures. The manufacturer may use less accurate estimates of the surface area if it is
ensured that the surface area will not be overestimated.
2 © ISO 2020 – All rights reserved
4.3.3 The fuel tank shall be filled with the reference fuel to its nominal capacity.
4.3.4 The tank and fuel shall equilibrate to 301,2 K ± 5,0 K or 316,2 K ± 5,0 K in the case of the
alternative short test.
4.3.5 The fuel tank shall be sealed using fuel caps and other fittings (excluding petcocks) that can be
used to seal openings in a production fuel tank. In cases where openings are not normally sealed on the
fuel tank (such as hose-connection fittings and vents in fuel caps), these openings may be sealed using
non-permeable fittings such as metal or fluoropolymer plugs.
4.4 Fuel tank permeation test procedure
To run the test, the following steps shall be taken for a tank preconditioned as specified in 4.3.
4.4.1 Weigh the sealed fuel tank and record the weight in milligrams. This measurement shall be taken
within 8 h of filling of the tank with test fuel.
4.4.2 The tank shall be placed in a ventilated, temperature-controlled room or enclosure.
4.4.3 The test room or enclosure shall be closed and sealed and the test time shall be recorded.
4.4.4 The test room or enclosure temperature shall be continuously maintained at 301,2 K ± 5,0 K for
14 days. This temperature shall be continuously monitored and recorded.
4.5 Fuel tank permeation test result calculation
4.5.1 At the end of the soak period, the weight in milligrams of the sealed fuel tank shall be recorded.
Unless the same fuel is used in the preconditioning fuel soak and the permeation test run, weight
measurements shall be recorded on five separate days per week of testing. The test is void if a linear
plot of tank weight vs. test days for the full soak period for permeation testing yields a linear regression
correlation coefficient r < 0,8.
4.5.2 The weight of the filled fuel tank at the end of the test shall be subtracted from the weight of the
filled fuel tank at the beginning of the test.
4.5.3 The difference in mass shall be divided by the internal surface area of the fuel tank.
4.5.4 The result obtained in 4.5.3, expressed in mg/m , shall be divided by the number of test days to
calculate the (mg/m )/day emission rate and rounded to integer value.
4.5.5 In cases where permeation rates during a soak period of 14 days are not long enough to be able
to measure significant weight changes, the period may be extended by a maximum of 14 additional days.
In this case, the test steps in 4.5.2 to 4.5.4 shall be repeated to determine the weight change for the full
28 days.
4.5.6 Determination of the deterioration factor when applying the full permeation test
procedure
The deterioration factor (DF) shall be determined from any of the following choices:
— the ratio between the final permeation and baseline test runs;
— fixed DF for total hydrocarbons regulated in each country.
4.5.7 Determination of the final tank permeation test results
4.5.7.1 Full test procedure
To determine the permeation test result, the deterioration factor determined in 4.5.6 shall be multiplied
by the measured permeation test result determined in 4.5.4.
4.6 Fuel tank durability testing
4.6.1 A separate durability demonstration for each substantially different combination of treatment
approaches and fuel tank materials shall be performed by taking the following steps.
4.6.1.1 Pressure cycling
A pressure test shall be conducted by sealing the tank and cycling it between 115,1 kPa absolute
pressure and 97,9 kPa absolute pressure and back to 115,1 kPa absolute pressure for 10 000 cycles at a
rate of 60 s per cycle.
4.6.1.2 UV exposure
A sunlight exposure test shall be conducted by exposing the fuel tank to an ultraviolet light of at least
2 2
24 W/m (0,40 (W·h/m )/min) on the tank surface for at least 450 h. Alternatively, the non-metallic
fuel tank may be exposed to direct natural sunlight for an equivalent period of time, as long as it is
ensured that it is exposed to at least 450 daylight hours.
4.6.1.3 Slosh testing
A slosh test shall be conducted by filling the non-metallic fuel tank to 40 % of its capacity with the
reference fuel set out in 4.2 or with a commercial premium-grade fuel at the choice of the manufacturer.
The fuel tank assembly shall be rocked at a rate of 15 cycles per minute until 1 000 000 total cycles are
reached. An angle deviation of +15° to –15° from level shall be used
...
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