ISO 6855-1:2012
(Main)Mopeds — Measurement method for gaseous exhaust emissions and fuel consumption — Part 1: General test requirements
Mopeds — Measurement method for gaseous exhaust emissions and fuel consumption — Part 1: General test requirements
ISO 6855-1:2012 specifies the general test requirements for measurement for the gaseous exhaust emissions from mopeds, and for determining the fuel consumption of mopeds as defined in ISO 3833. It is applicable to mopeds equipped with a spark ignition engine (four-stroke engine, two-stroke engine or rotary piston engine).
Cyclomoteurs — Méthode de mesure des émissions de gaz polluants et de consommation de combustible — Partie 1: Exigences générales d'essai
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INTERNATIONAL ISO
STANDARD 6855-1
First edition
2012-09-15
Mopeds — Measurement method for
gaseous exhaust emissions and fuel
consumption —
Part 1:
General test requirements
Cyclomoteurs — Méthode de mesure des émissions de gaz polluants et
de consommation de combustible —
Partie 1: Exigences générales d’essai
Reference number
ISO 6855-1:2012(E)
©
ISO 2012
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ISO 6855-1:2012(E)
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Published in Switzerland
ii © ISO 2012 – All rights reserved
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ISO 6855-1:2012(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Standard reference conditions . 4
6 Tests . 4
6.1 Measurement of gaseous exhaust emissions . 4
6.2 Measurement of fuel consumption . 5
7 Measurement equipment . 5
7.1 Chassis dynamometer . 5
7.2 Gas-collection equipment . 5
7.3 Analytical equipment . 6
7.4 Cooling equipment. 6
7.5 Fuel consumption measurement . 7
7.6 Accuracy of instruments and measurements . 7
8 Preparing the test . 8
8.1 Engine fuel and lubricants . 8
8.2 Description of the test moped. 8
8.3 Conditioning/preparation of the test moped . 8
8.4 Adjustment of the analytical apparatus . . 8
9 System check procedure . 9
9.1 Accuracy of the CVS system . 9
9.2 Metering a constant flow of pure gas (CO or C H ) using a critical flow orifice . 9
3 8
9.3 Metering a limited quantity of pure gas (CO or C H ) by means of a
3 8
gravimetric technique . 9
10 Procedure for sampling, analysing and measuring the volume of gaseous
exhaust emissions . 9
10.1 Operations to be carried out before the moped start up . 9
10.2 Beginning of sampling and volume measurement .12
10.3 End of sampling and volume measurement .12
10.4 Analysis.12
10.5 Measuring the driving distance .13
10.6 Open type CVS system .13
11 Determination of the quantity of gaseous exhaust emissions .13
11.1 Total diluted exhaust mixture volume corrected to the standard reference conditions .13
11.2 Exhaust gas sampling and the dilution factor .14
11.3 Mass of the gaseous exhaust emissions .14
12 Determination of the fuel consumption .16
12.1 Carbon balance method .16
12.2 Fuel flow measurement method .17
12.3 Calculation of results in litres per 100 km .18
12.4 Criteria of the statistical accuracy for the fuel consumption measurements .18
Annex A (normative) Method and equipment for measuring fuel consumption by the fuel flow
measurement method .19
Annex B (informative) Example for record form of test fuel specifications .30
Annex C (informative) Exhaust gas leakage check procedure for the open type CVS system.31
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ISO 6855-1:2012(E)
Annex D (informative) Determination of the dilution factor .36
Annex E (informative) Principle of the carbon balance method .44
Annex F (informative) Simplified determination method of the atom number ratio of hydrogen
and carbon, and that of oxygen and carbon in gasoline .47
Annex G (normative) Fuel consumption for two-stroke engines .49
Annex H (informative) Criteria of the statistical accuracy for the fuel
consumption measurements .50
Bibliography .52
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ISO 6855-1:2012(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
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.
ISO 6855-1 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 23, Mopeds.
ISO 6855-1 cancels and replaces ISO 6855:1983 and ISO 7859:2000, both of which have been
technically revised.
ISO 6855 consists of the following parts, under the general title Mopeds — Measurement method for
gaseous exhaust emissions and fuel consumption:
— Part 1: General test requirements
— Part 2: Test cycles and specific test conditions
— Part 3: Fuel consumption measurement at a constant speed
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ISO 6855-1:2012(E)
Introduction
For measurement of moped fuel consumption, the carbon balance method, where the fuel consumption
is calculated from analysis of the carbon quantity in the exhaust gas, is now widely used in addition to
the conventional fuel flow measurement. Therefore, the measurement of exhaust gas and that of fuel
consumption are inseparably related to each other.
ISO 6855 now covers in one single series of standards the two subjects that were previously covered
separately by ISO 6855:1983 and by ISO 7859:2000. This part of ISO 6855 defines fundamental elements
such as the measurement accuracy, test vehicle conditions and the details of the carbon balance method.
Measurement of gaseous exhaust gas emissions and fuel consumption of test cycles can be conducted
with this part of ISO 6855 and ISO 6855-2. Together with ISO 6855-3, they also give details of those
measurements at a constant speed.
While the most up-to-date technologies are reflected in the ISO 6855 series, further technical
development in the following aspects will be necessary in the future, when measurement of exhaust gas
at a lower level is required:
— cleaning of the background air (i.e the air in the test room which is used for the dilution air);
— heating of the sampling line;
— control of the test room humidity;
— the exhaust gas analysis system for low-level emissions;
— consideration for the evaporated fuel from the test moped.
In addition to the above future issues, the chassis dynamometer with electrically simulated inertia is
at the stage of practical application. Standardization of the verification method and the allowance of
simulated inertia would be necessary for this recent development.
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INTERNATIONAL STANDARD ISO 6855-1:2012(E)
Mopeds — Measurement method for gaseous exhaust
emissions and fuel consumption —
Part 1:
General test requirements
1 Scope
This part of ISO 6855 specifies the general test requirements for measurement for the gaseous exhaust
emissions from mopeds, and for determining the fuel consumption of mopeds as defined in ISO 3833. It
is applicable to mopeds equipped with a spark ignition engine (four-stroke engine, two-stroke engine or
rotary piston engine).
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 3833, Road vehicles — Types — Terms and definitions
ISO 6855-2:2012,Mopeds — Measurement method for gaseous exhaust emissions and fuel consumption —
Part 2: Test cycles and specific test conditions
ISO 6855-3:2012, Mopeds — Measurement method for gaseous exhaust emissions and fuel consumption —
Part 3: Fuel consumption measurement at a constant speed
ISO 28981, Mopeds — Methods for setting the running resistance on a chassis dynamometer
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3833 and the following apply.
3.1
moped kerb mass
dry mass of the moped to which is added the mass of the following:
— fuel: tank filled at least to 90 % of the capacity specified by the manufacturer;
— auxiliary equipment usually supplied by the manufacturer in addition to that necessary for normal
operation [tool-kit, carrier(s), windscreen(s), protective equipment, etc.]
3.2
reference mass of the moped
kerb mass of the moped increased by a uniform figure of 75 kg, which represents the mass of a rider
3.3
equivalent inertia
total inertia of the rotating masses of the test bench, determined with respect to the reference mass of
the moped
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ISO 6855-1:2012(E)
3.4
gaseous exhaust emissions
carbon monoxide, hydrocarbons, nitrogen oxides (gaseous pollutants) and carbon dioxide emitted from
mopeds
4 Symbols
Table 1 — Symbols
a
Symbols Definition Unit
a mixing ratio of lubrication oil and fuel ─
c carbon monoxide concentration in the dilution air ppm
CO,d
c carbon monoxide concentration in the dilution air with the water vapour and carbon ppm
CO,dm
dioxide absorbent
c carbon monoxide concentration in the diluted exhaust mixture ppm
CO,e
c volumetric concentration of carbon monoxide in the diluted exhaust mixture, cor- ppm
CO,ec
rected to take account of carbon monoxide in the dilution air
c carbon monoxide concentration in the diluted exhaust mixture with the water ppm
CO,em
vapour and carbon dioxide absorbent
c carbon dioxide concentration in the dilution air %
CO2,d
c carbon dioxide concentration in the diluted exhaust mixture %
CO2,e
c volumetric concentration of carbon dioxide in the diluted exhaust mixture, corrected %
CO2,ec
to take account of carbon dioxide in the dilution air
c nitrogen oxides concentration in the dilution air ppm
NOx,d
c nitrogen oxides concentration in the diluted exhaust mixture ppm
NOx,e
c volumetric concentration of nitrogen oxides in the diluted exhaust mixture, cor- ppm
NOx,ec
rected to take account of nitrogen oxides in the dilution air
c oxygen concentration in the dilution air %
O2,d
c concentration of the pollutant i in the diluted exhaust mixture, corrected to take ppm
Pi,ec
account of the amount of the pollutant i contained in the dilution air
c hydrocarbon concentration in the dilution air as measured in parts per million car- ppmC
THC,d
bon equivalent
c hydrocarbon concentration in the diluted exhaust mixture as measured in parts per ppmC
THC,e
million carbon equivalent
c volumetric concentration, expressed in parts per million carbon equivalent, of ppmC
THC,ec
hydrocarbon in the diluted exhaust mixture, corrected to take account of hydrocar-
bon in the dilution air
D dilution factor ─
f
F specific fuel consumption km/L
c
F’ specific fuel consumption for lubrication oil mixed fuel km/L
c
F fuel consumption per 100 km L/100 km
c100
F lubrication oil consumption for the mixed fuel km/L
o
H absolute humidity in grams of water per kilogram of dry air ─
a
H relative humidity of dilution air %
d
H relative humidity in the test room %
r
H standard relative humidity %
0
a
ppm = parts per million.
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ISO 6855-1:2012(E)
Table 1 (continued)
a
Symbols Definition Unit
K humidity correction factor used for the calculation of the mass emissions of nitrogen ─
H
oxides
K venturi correction factor ─
1
K ratio of pressure to temperature at the standard reference conditions ─
2
L running distance actually travelled km
m mass of carbon monoxide in the exhaust gas g/km
CO
m mass of carbon dioxide in the exhaust gas g/km
CO2
m fuel consumed g
f
m mass of nitrogen oxides in the exhaust gas g/km
NOx
m mass emission of the pollutant i g
Pi
m mass of hydrocarbon in the exhaust gas g/km
THC
N number of revolutions of positive displacement pump during the test while samples ─
are being collected
p mean barometric pressure during the test in the test room kPa
a
p saturated water vapour pressure during the test in the test room kPa
d
p diluted exhaust mixture absolute pressure at the inlet of positive displacement pump kPa
p
p absolute pressure at the venturi inlet kPa
V
p (t) absolute pressure of the diluted exhaust mixture at the venturi inlet kPa
V
p total barometric pressure at the standard reference conditions kPa
0
Q measured flow rate of venturi at ambient conditions L/s
a
Q measured flow rate of venturi using the other gas flowmeter L/s
cal
R atom number ratio of hydrogen and carbon in the exhaust gas ─
HC,ex
R’ atom number ratio of hydrogen and carbon in the exhaust gas for lubrication oil ─
HC,ex
mixed fuel
R atom number ratio of hydrogen and carbon in the fuel ─
HC,f
R atom number ratio of hydrogen and carbon in the lubrication oil ─
HC,o
R atom number ratio of oxygen and carbon in the exhaust gas ─
OC,ex
R’ atom number ratio of oxygen and carbon in the exhaust gas for lubrication oil mixed ─
OC,ex
fuel
R atom number ratio of oxygen and carbon in the fuel ─
OC,f
R atom number ratio of oxygen and carbon in the lubrication oil ─
OC,o
r relative air density at the standard reference conditions ─
0
t time s
t total test time s
test
T measured ambient temperature during the test in the test room K
a
T fuel temperature measured at the burette K
f
T temperature of diluted exhaust mixture at the positive displacement pump inlet dur- K
p
ing the test while samples are being collected
T temperature at the venturi inlet K
v
T (t) temperature of diluted exhaust mixture at the venturi inlet K
v
T air temperature at the standard reference conditions K
0
a
ppm = parts per million.
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ISO 6855-1:2012(E)
Table 1 (continued)
a
Symbols Definition Unit
T mean dry bulb temperature during the test in the test room K
1
T mean wet bulb temperature during the test in the test room K
2
V measured volume of fuel consumed L
V dilution air volume L
d
V volume of the diluted exhaust mixture expressed corrected to the standard refer- L/km
e
ence conditions
V exhaust gas volume L
ex
V fuel volume of lubrication oil mixed fuel L
f
V volume of the diluted exhaust mixture in one test under the standard reference con- L
i,e
ditions
V lubrication oil volume of lubrication oil mixed fuel L
o
V diluted exhaust mixture volume pumped by the positive displacement pump per one L
p
revolution
V total diluted exhaust mixture volume during one test L
s
−1
α coefficient of volumetric expansion for the fuel K
ρ carbon monoxide density at the standard reference conditions g/L
CO
ρ carbon dioxide density at the standard reference conditions g/L
CO2
ρ fuel density at 293,15 K g/L
f
ρ nitrogen oxides density under the standard reference conditions, expressed in g/L
NOx
equivalent NO
2
ρ lubrication oil density at 293,15 K g/L
o
ρ density of the pollutant i under the standard reference conditions g/L
Pi
ρ hydrocarbon density at the standard reference conditions g/L
THC
3
ρ air volumetric mass at the standard reference conditions kg/m
0
a
ppm = parts per million.
5 Standard reference conditions
The standard reference conditions shall be as follows:
a) total barometric pressure, p : 101,325 kPa;
0
b) air temperature, T : 293,15 K;
0
c) relative humidity, H : 65 %;
0
3
d) air volumetric mass, ρ : 1,205 kg/m ;
0
e) relative air density, r : 0,931 9.
0
6 Tests
6.1 Measurement of gaseous exhaust emissions
6.1.1 Average gaseous exhaust emissions during conventional test cycles
The test shall be carried out in accordance with the method described in ISO 6855-2.
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ISO 6855-1:2012(E)
6.1.2 The gaseous exhaust emissions measurement at an idling speed
The test shall be carried out in accordance with the procedure described in ISO 6855-2.
6.2 Measurement of fuel consumption
6.2.1 Average fuel consumption during conventional test cycles
The test shall be carried out in accordance with the procedure described in ISO 6855-2.
6.2.2 Fuel consumption at a constant speed
The test shall be carried out in accordance with the procedure describedin ISO 6855-3.
7 Measurement equipment
Irrespective of the provisions specified below, any measurement system(s) may be used when the
performance of the equipment is proven by the equipment manufacturer to be equivalent to CVS
(constant volume sampling) system.
7.1 Chassis dynamometer
The chassis dynamometer shall be set in accordance with ISO 28981.
7.2 Gas-collection equipment
7.2.1 The gas-collection device, shall be a closed type device that can collect all exhaust gases at
the moped exhaust outlet(s) while maintaining atmospheric pressure at the exhaust outlet(s). An open
system may be used as well if it is confirmed that all the exhaust gases are collected. The gas collection
shall be such that there is no condensation, which could appreciably modify the nature of exhaust gases
at the test temperature.
7.2.2 A connecting tube, between the device and the exhaust gas sampling system. This tube, and the
device, shall be made of stainless steel, or of some other material which does not affect the composition
of the gases collected, and which withstands the temperature of these gases.
7.2.3 A heat exchanger, capable of limiting the temperature variation of the diluted exhaust mixture in the
pump intake to ± 5 K throughout the test. This exchanger shall be equipped with a preheating system capable
of bringing the exchanger to its operating temperature (with the tolerance of ± 5 K) before the test begins.
7.2.4 A positive displacement pump (PDP), to draw in the diluted exhaust mixture. This pump is
equipped with a motor having several strictly controlled uniform speeds. The pump capacity shall be
large enough to ensure the intake of all the exhaust gases.
7.2.5 A critical flow venturi (CFV) may also be used.
7.2.6 A device to allow continuous recording of the temperature of diluted exhaust mixture entering
the pump.
7.2.7 Two gauges:
— one to ensure the pressure depression of the diluted exhaust mixture entering the pump, relative to
atmospheric pressure;
— one to measure the dynamic pressure variation of the positive displacement pump.
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ISO 6855-1:2012(E)
7.2.8 A probe, located near to but outside the gas-collecting device, to collect, through a pump, a filter
and a flowmeter, samples of the dilution air stream, at constant flow rates, throughout the test.
7.2.9 A sample probe, pointed upstream into the diluted exhaust mixture flow, upstream of the positive
displacement pump or the critical flow venturi to collect, through a pump, a filter and a flowmeter, samples
of the diluted exhaust mixture, at constant flow rates, throughout the test.
The minimum sample flow rate in the two sampling devices described in 7.2.8 and 7.2.9 shall be 150 L/h.
7.2.10 Three way valves, on the sampling system, described in 7.2.8 and 7.2.9, to direct the samples
either to their respective bags or to the outside throughout the test.
7.2.11 Gas-tight collection bags, for dilution air and diluted exhaust mixture of sufficient capacity
so as not to impede normal sample flow and which will not change the nature of the gaseous exhaust
emissions concerned.
The bags shall have an automatic self-locking device, and shall be easily and tightly fastened either to the
sampling system or the analysing system at the end of the test.
7.2.12 A revolution counter, to count the revolutions of the positive displacement pump throughout the
test.
Good care shall be taken with the connecting method and the material or configuration of the connecting
parts because there is a possibility that each section (e.g. the adapter and the coupler) of the sampling
system will become very hot. If the measurement cannot be performed normally due to heat-damages of
the sampling system, an auxiliary cooling device may be used as long as the exhaust gases are not affected.
NOTE 1 With open type devices, there is a risk of incomplete gas collection and gas leakage into the test room,
so it is important to make sure that there is no leakage throughout the sampling period.
NOTE 2 If a constant CVS flow rate is used throughout the test cycle that includes low and high speeds all in
one, it is advisable that special attention be paid because of higher risk of water condensation in high speed range.
7.3 Analytical equipment
7.3.1 The sample probe shall consist of a sampling tube leading into the collecting bags, or of a drainage
tube. This sample probe shall be made of stainless steel or of some other material that will not adversely
affect the composition of the gases to be analysed. The sample probe as well as the tube taking the gases
to the analyser shall be at ambient temperature.
7.3.2 Analysers shall be of the following types:
a) non-dispersive type with absorption in the infrared for carbon monoxide and carbon dioxide;
b) flame ionization type for total hydrocarbons (diluted measurements);
c) non-dispersive type with absorption in the infrared for hydrocarbons (direct measurements);
d) chemiluminescence type for nitrogen oxides.
7.4 Cooling equipment
Throughout the test, a variable speed cooling blower shall be positioned in front of the moped, so as to
direct the cooling air to the moped in a manner which simulates actual operating conditions. The blower
speed shall be such that, within the operating range of 10 to 50 km/h, the linear velocity of the air at the
blower outlet is within ± 5 km/h of the corresponding roller speed. At roller speeds of less than 10 km/h,
air velocity may be zero.
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ISO 6855-1:2012(E)
As far as possible, the air speed shall be constant across the whole outlet section.
2
The blower outlet shall have a cross-section area of at least 0,2 m and the bottom of the bl
...
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