1972L0306 — EN — 05.06.1997 — 002.001 — 1
This document is meant purely as a documentation tool and the institutions do not assume any liability for its contents
►B COUNCILDIRECTIVE
of2August1972
ontheapproximationofthelawsoftheMemberStatesrelatingtothemeasurestobetakenagainst
theemissionofpollutantsfromdieselenginesforuseinvehicles
(72/306/EEC)
(OJ L 190, 20.8.1972, p. 1)
Amended by:
Official Journal
No page date
►M1 Commission Directive 89/491/EEC of 17 July 1989 L 238 43 15.8.1989
►M2 Commission Directive 97/20/EC of 18 April 1997 L 125 21 16.5.1997
Corrected by:
►C1 Corrigendum, OJ L 215, 6.8.1974, p. 20 (72/306/EEC)
►C2 Corrigendum, OJ L 299, 23.11.1977, p. 27 (72/306/EEC)
▼B
COUNCILDIRECTIVE
of2August1972
on the approximationof the lawsofthe Member States relating to
the measures to be taken against the emission of pollutants from
dieselenginesforuseinvehicles
(72/306/EEC)
THE COUNCIL OF THE EUROPEAN COMMUNITIES,
Having regard to the Treaty establishing the European Economic
Community, and in particular Article 100 thereof;
Having regard to the proposal from the Commission;Having regard to the Opinion of the European Parliament;Having regard to the Opinion of the Economic and Social Committee;Whereas the technical requirements which motor vehicles must satisfy
pursuant to national laws relate, interalia , to the emission of pollutants
from diesel engines for use in vehicles;
Whereas those requirements differ from one Member State to another;
whereas it is therefore necessary that all the Member States adopt thesame requirements either in addition to or in place of their existing rules,
in order, in particular, to allow the EEC type approval procedure which
was the subject of the Council Directive (
1) of 6 February 1970 on the
approximation of the laws of the Member States relating to the typeapproval of motor vehicles and their trailers to be applied in respect ofeach type of vehicle;
Whereas, it is desirable to follow the technical requirements adopted by
the UN Economic Commission for Europe in its Regulation No 24
(Uniform provisions concerning the approval of vehicles equipped with
diesel engines with regard to the emission of pollutants by the engine),which is annexed to the Agreement of 20 March 1958 concerning theadoption of uniform conditions of approval and reciprocal recognition ofapproval for motor vehicle equipment and parts (
2);
HAS ADOPTED THIS DIRECTIVE:
Article 1
For the purposes of this Directive ‘vehicle’ means any vehicle with a
diesel engine, intended for use on the road, with or without bodywork,having at least four wheels and a maximum design speed exceeding25 km/h, with the exception of vehicles which run on rails and ofagricultural and forestry tractors and of all mobile machinery.
Article 2
No Member State may refuse to grant a vehicle EEC type approval or
national type approval on the ground that pollutants are emitted by thediesel engine which drives the vehicle, if the engine complies with
►
M2the requirements of the relevant Annexes to this Directive ◄.
Article 3
The Member State which has granted type approval shall take the
necessary measures to ensure that it is informed of any modification of a
part or characteristic referred to in ►M2item 1.1 ◄of Annex I. The
competent authorities of that Member State shall decide whether freshtests should be carried out on the ►
C1modified vehicle type ◄and a1972L0306 — EN — 05.06.1997 — 002.001 — 2
(1) OJ No L 42, 23.2.1970, p. 1.
(2) Doc. E/EEC/324 — E/EEC/TRANS/505, Rev 1/add 23, 23.8.1971.▼M2
▼B
▼B
fresh report drawn up. Where the tests reveal failure to comply with this
Directive, the modification shall not be approved.
Article 4
The amendments necessary for adjusting the Annexes so as to take
account of technical progress shall be adopted in accordance with the
procedure laid down in Article 13 of the Council Directive of 6 February
1970 on the approximation of the laws of the Member States relating tothe type approval of motor vehicles and their trailers.
Article 5
1. Member States shall put into force the provisions needed in order
to comply with this Directive within eighteen months of its notificationand shall forthwith inform the Commission thereof.
2. Furthermore, once notification of this directive has been effected
the Member States shall ensure that the Commission is informed, in time
for it to submit its comments, of the most important laws, regulations
and administrative provisions which they envisage adopting in the fieldcovered by this Directive.
Article 6
This Directive is addressed to the Member States.1972L0306 — EN — 05.06.1997 — 002.001 — 3
▼M2
LISTOFANNEXES
AnnexI: Definitions, application for EC type-approval, granting of EC
type-approval, symbol of the corrected absorption coefficient,
specifications and tests, modifications of the type, conformity
of production
Appendix1:InformationdocumentAppendix2:Type-approvalcertificate
AnnexII: Example of the symbol of the corrected absorption coefficient
AnnexIII: Test at steady speeds over the full-load curve
AnnexIV: Test under free acceleration
AnnexV: Technical characteristics of reference fuel
AnnexVI: Limit values applicable in the test at steady speeds
AnnexVII: Characteristics of opacimeters
AnnexVIII: Installation and use of the opacimeter.1972L0306 — EN — 05.06.1997 — 002.001 — 4
▼B
ANNEX1 ►M2 ◄
DEFINITIONS,APPLICATIONFORECTYPE-APPROVAL,GRANTING
OF EC TYPE-APPROVAL, SYMBOL OF THE CORRECTED ABSORP-
TION COEFFICIENT, SPECIFICATIONS AND TESTS,
MODIFICATIONSOFTHETYPE,CONFORMITYOFPRODUCTION
►M21.◄DEFINITIONS
For the purposes of this Directive:
►M21.1.◄‘Vehicle type as regards the limitation of the emission of
pollutants from the engine’ means motor vehicles which do not differ in
such essential respects as the vehicle and engine characteristics defined
in►M2Appendix 1 ◄;
►M21.2.◄‘Diesel engine’ means an engine which works on the compres-
sion-ignition principle;
►M21.3.◄‘Cold-start device’ means a device which by its operation
temporarily increases the amount of fuel supplied to the engine and is
intended fo facilitate the starting of the engine;
►M21.4.◄‘Opacimeter’ means an instrument for continuous measurement
of the absorption coefficients of the light by the exhaust gases emitted byvehicles.
►
M22.◄APPLICATIONFOREECTYPEAPPROVAL
2.1.TheapplicationforECtype-approvalpursuanttoArticle3(4)of
Directive70/156/EECofavehicletypewithregardtoitsemissionof
pollutantsfromdieselenginesshallbesubmittedbythemanufacturer.
2.2.AmodelfortheinformationdocumentisgiveninAppendix1.
►M22.3.◄An engine and the equipment prescribed in ►M2Appendix
1◄for fitting to the vehicle to be approved shall be submitted to the
technical service conducting the approval tests defined in item 5.
However, if the manufacturer so requests and the technical service
conducting the approval tests agrees, a test may be carried out on a
vehicle representative of the vehicle type to be approved.
3. GRANTING OF EC TYPE-APPROVAL
3.1. If the relevant requirements are satisfied, EC type-approval pursuant to
Article 4 (3) and, if applicable, Article 4 (4) of Directive 70/156/EEC
shall be granted.
3.2. A model for the EC type-approval certificate is given in Appendix 2.
3.3. An approval number in accordance with Annex VII to Directive 70/156/
EEC shall be assigned to each type of vehicle approved. The same
Member State shall not assign the same number to another type of
vehicle.
4. SYMBOL OF THE CORRECTED ABSORPTION COEFFICIENT
►M24.1.◄To every vehicle conforming to a vehicle type approved under
this Regulation there shall be affixed, conspicuously and in a readily
accessible place specified in the ►M2Addendum to the type-approval
certificate shown in Appendix 2 ◄, a symbol being a rectangle
surrounding a figure expressing in m−1the corrected absorption
coefficient obtained, at the time of approval, during the test under freeacceleration, and determined at the time of approval by the methoddescribed in item 3.2 of Annex IV.
►
M24.2.◄The symbol must be clearly legible and indelible.
►M24.3.◄►M2Annex II ◄gives an example of the symbol.1972L0306 — EN — 05.06.1997 — 002.001 — 5
▼M2
▼B
▼M2
▼B▼B
▼M2
▼B
5. SPECIFICATIONS AND TESTS
5.1.General
The components liable to affect the emission of pollutants shall be so
designed, constructed and assembled as to enable the vehicle, in normal
use, despite the vibration to which it may be subjected, to comply with
the provisions of this Directive.
5.2.Specificationsconcerningcold-startdevices
5.2.1. The cold-start device shall be so designed and constructed that it cannot
be brought into or kept in action when the engine is running normally.
5.2.2. The provisions of item 5.2.1 above shall not apply if at least one of the
following conditions is met:
5.2.2.1. The light absorption coefficient of the gases emitted by the engine at
steady speeds when measured by the method described in Annex III with
the cold-start device operating is within the limits prescribed in Annex
VI.
5.2.2.2. Keeping the cold-start device in operation causes the engine to stop
within a reasonable time.
5.3.Specificationsconcerningtheemissionofpollutants
5.3.1. The emission of pollutants by the vehicle type submitted for approval
shall be measured by the two methods described in Annexes III and IV,
relating respectively to tests at steady speeds and to tests under free
acceleration. (a)
5.3.2. The emission of pollutants, as measured by the method described in
Annex III, shall not exceed the limits prescribed in Annex VI.
5.3.3. In the case of engines with an exhaust-driven supercharger the absorption
coefficient measured under free acceleration shall not exceed the limit
prescribed in Annex VI for the nominal flow value corresponding to the
maximum absorption coefficient measured during the tests at steady
speeds, plus 0·5 m−1.
5.4. Equivalent measuring instruments shall be allowed. If an instrument
other than those described in Annex VII is used, proof of its equivalence
for the engine considered shall be required.
6. MODIFICATIONS OF THE TYPE AND AMENDMENTS TO
APPROVALS
6.1. In the case of modifications of the type approved pursuant to this
Directive, the provisions of Article 5 of Directive 70/156/EEC shall
apply.
7. CONFORMITY OF PRODUCTION
7.1. Measures to ensure the conformity of production shall be taken in
accordance with the provisions laid down in Article 10 of Directive 70/
156/EEC.
7.2. In particular, conformity of the vehicle with the approved type as regards
the emission of pollutants from diesel engines shall be verified on the
basis of the results listed in the Addendum to the type-approval
certificate shown in Appendix 2. In addition:
►M27.2.1.◄Where a check is carried out on a vehicle taken from the series,
the tests shall be carried out as follows:
►M27.2.1.1.◄A vehicle which has not been run in shall be subjected to the
test under free acceleration described in Annex IV. The vehicle shall be
deemed to conform to the approved type if the absorption coefficient
determined does not exceed by more than 0·5 m−1the figure shown in the
approval mark.1972L0306 — EN — 05.06.1997 — 002.001 — 6
(a) A test under free acceleration shall be carried out, especially in order to provide a
reference figure for administrations which use this method to check vehicles in use.▼M2
▼B
▼M2
▼B
▼B
►M27.2.1.2.◄If the figure determined in the test referred to in item
►M27.2.1.1◄above exceeds by more than 0·5 m−1the figure shown
in the approval mark, a vehicle of the type considered or its engine shall
be subjected to the test at steady speeds over the full-load curve, as
described in Annex III. The emission levels shall not exceed the limits
prescribed in Annex VI.1972L0306 — EN — 05.06.1997 — 002.001 — 7
▼M2
▼M2
Appendix1
INFORMATIONDOCUMENTNO…
pursuanttoAnnexItoCouncilDirective70/156/EEC (1)relatingtoECtype-approvalofavehicle
withrespecttothemeasurestobetakenagainsttheemissionofpollutantsfromdieselengines
(Directive 72/306/EEC, aslastamendedbyDirective …/…/EC)
1972L0306 — EN — 05.06.1997 — 002.001 — 8
(1) The item numbers and footnotes used in this information document correspond to those set out in Annex I to
Directive 70/156/EEC. Items not relevant for the purpose of this Directive are omitted.
▼M2
1972L0306 — EN — 05.06.1997 — 002.001 — 9
▼M2
1972L0306 — EN — 05.06.1997 — 002.001 — 10
▼M2
1972L0306 — EN — 05.06.1997 — 002.001 — 11
▼M2
AddendumtoAppendix 1
INFORMATIONONTESTCONDITIONS
1972L0306 — EN — 05.06.1997 — 002.001 — 12
▼M2
Appendix2
MODEL
(maximum format: A4 (210 × 297 mm))
1972L0306 — EN — 05.06.1997 — 002.001 — 13
▼M2
1972L0306 — EN — 05.06.1997 — 002.001 — 14
▼M2
AddendumtoECtype-approval certificate No…
concerning the type-approval of a vehicle with regard to Directive 72/306/EEC, as last amended by
Directive …/…/EC
1972L0306 — EN — 05.06.1997 — 002.001 — 15
▼M2
ANNEX II
EXAMPLEOFTHESYMBOLOFTHECORRECTEDABSORPTIONCOEFFICIENT
Theabovesymbolshowsthatthecorrectedabsorptioncoefficientis1·30m−1.1972L0306 — EN — 05.06.1997 — 002.001 — 16
▼B
ANNEX III
TESTATSTEADYSPEEDSOVERTHEFULL-LOADCURVE
1. INTRODUCTION
1.1. This annex describes the method of determining emissions of pollutants at
different steady speeds over the full-load curve.
1.2. The test may be carried out either on an engine or on a vehicle.
2. MEASUREMENT PRINCIPLE
2.1. The opacity of the exhaust gases produced by the engine shall be measured
with the engine running under full load and at steady speed. Six
measurements shall be made at engine speeds spaced out uniformly
between that corresponding to maximum power and the higher of the
following two engine speeds:
— 45 per cent of the engine speed corresponding to maximum power; and
— 1 000 rpm.
The extreme points of measurement shall be situated at the limits of the
interval defined above.
2.2. In the case of diesel engines which are fitted with an air supercharger
which can be engaged at will, and in which engines the entry into
operation of the air supercharger automatically brings about an increase in
the quantity of fuel injected, the measurements shall be made both with
and without the supercharger working.
For each engine speed, the result of the measurement shall be the higher of
the two figures obtained.
3. TEST CONDITIONS3.1.Vehicleorengine
3.1.1. The engine or the vehicle shall be submitted in good mechanical condition.
The engine shall have been run in.
3.1.2. The engine shall be tested with the equipment described in
►
M2Appendix 1 to Annex I ◄.
3.1.3. The settings of the engine shall be those described by the manufacturer and
by►M2Appendix 1 to Annex I ◄.
3.1.4. The exhaust device shall not have any orifice through which the gases
emitted by the engine might be diluted.
3.1.5. The engine shall be in the normal working condition prescribed by the
manufacturer. In particular, the cooling water and the oil shall each be at
the normal temperature indicated by the manufacturer.
3.2.Fuel
The fuel shall be the reference fuel whose specifications are given in
Annex V.
3.3.Testlaboratory
3.3.1. The absolute temperature T of the laboratory, expressed in degrees Kelvin,
and the atmospheric pressure H, expressed in torr, shall be measured, and
the factor F shall be determined by the formula
F¼750
H/C18/C190/C165
/C2T
298/C18/C190/C15
3.3.2. For a test to be recognized as valid, the factor F shall be such that 0·98 ≤
F≤1·02.
3.4.Samplingandmeasuringapparatus
The light-absorption coefficient of the exhaust gases shall be measured
with an opacimeter satisfying the conditions laid down in Annex VII and
installed in conformity with Annex VIII.1972L0306 — EN — 05.06.1997 — 002.001 — 17
▼B
4. LIMIT VALUES
4.1. For each of the six engine speeds at which the absorption coefficient is
measured pursuant to paragraph 2.1 above, the nominal gas flow G,
expressed in litres per second, shall be calculated by means of the
following formulae:
—fortwo-strokeenginesG¼Vn
60
—forfour-strokeenginesG¼Vn
120
where:
V is the cylinder capacity of the engine expressed in litres; and
n is the engine speed in revolutions per minute.
4.2. For each engine speed the absorption coefficient of the exhaust gases shall
not exceed the limit value given in the table in Annex VI. Where the value
of the nominal flow is not one of those given in that table, the limit value
applicable shall be obtained by interpolation on the principle of
proportional parts.1972L0306 — EN — 05.06.1997 — 002.001 — 18
▼B
ANNEX IV
TESTUNDERFREEACCELERATION
1. TEST CONDITIONS
1.1. The test shall be carried out on the vehicle or engine which has undergone
the test at steady speeds described in Annex III.
1.1.1. If the engine is tested on a bench the test shall be carried out as soon as
possible after the test for measurement of opacity under full load at steady
speed. In particular, the cooling water and the oil shall be at the normal
temperatures indicated by the manufacturer.
1.1.2. If the test is carried out on a stationary vehicle, the engine shall first be
brought to normal operating condition by a road run. The test shall be
carried out as soon as possible after completion of the road run.
1.2. The combustion chamber shall not have been cooled or fouled by a
prolonged period of idling preceding the test.
1.3. The test conditions described in Annex III, items 3.1, 3.2 and 3.3, shall
apply.
1.4. The conditions described in Annex III, item 3.4, with regard to the
sampling and measuring apparatus shall apply.
2. TEST METHODS
2.1. If the test is a bench test, the engine shall be disconnected from the brake,
the latter being replaced either by the rotating parts driven when no gear is
engaged or by an inertia substantially equivalent to that of the rotating
parts.
2.2. If the test is carried out on a vehicle, the gear-change control shall be set in
the neutral position and the engine in gear.
2.3. With the engine idling, the accelerator control shall be operated quickly,
but not violently, so as to obtain maximum delivery from the injection
pump. This position shall be maintained until maximum engine speed is
reached and the governor comes into action. As soon as this speed is
reached the accelerator shall be released until the engine resumes its idling
speed and the opacimeter reverts to the corresponding conditions.
2.4. The operation described in item 2.3 above shall be repeated not less than
six times in order to clear the exhaust system and to allow for any
necessary adjustment of the apparatus. The maximum opacity values read
at each successive acceleration shall be noted until stabilized values are
obtained. No account shall be taken of the values read while the engine is
idling after each acceleration. The values read shall be regarded as
stabilized when four consecutive readings are situated within a band width
of 0·25 m−1and do not form a decreasing sequence. The absorption
coefficient XMto be recorded shall be the arithmetic mean of these four
values.
2.5. Engines fitted with an air supercharger shall be subject, where appropriate,
to the following special requirements:
2.5.1. In the case of engines with an air supercharger which is coupled with or
driven mechanically by the engine and is capable of being disengaged, two
complete measurement cycles with preliminary accelerations shall be
carried out, the air supercharger being engaged in one case and disengaged
in the other. The measurement result recorded shall be the higher of the
two results obtained;
2.5.2. In the case of engines with an air supercharger which can be cut out by
means of a driver-operated bypass, the test shall be carried out with and
without the bypass. The measurement result recorded shall be the higher of
the results obtained.
3. DETERMINATION OF THE CORRECTED VALUE OF THE ABSORP-
TION COEFFICIENT
3.1.Notation
XM= value of the absorption coefficient under free acceleration
measured as described in item 2.4 of this Annex;1972L0306 — EN — 05.06.1997 — 002.001 — 19
▼B
XL= corrected value of the absorption coefficient under free accelera-
tion;
SM= value of the absorption coefficient measured at steady speed
(Annex III, item 2.1.) which is closest to the prescribed limit
value corresponding to the same nominal flow;
SL= value of the absorption coefficient (Annex III, item 4.2.) for the
nominal flow corresponding to the point of measurement which
gave the value SM;
L = effective length of the light path in the opacimeter.
3.2. When the absorption coefficients are expressed in m−1and the effective
length of the light path in metres, the corrected value XLis given by the
smaller of the following two expressions:
X0
L¼SL
SM/C1XMor X00
L¼XMþ0/C151972L0306 — EN — 05.06.1997 — 002.001 — 20
▼B
ANNEX V
TECHNICALCHARACTERISTICSOFREFERENCEFUELPRESCRIBEDFORAPPROVAL
TESTSANDTOVERIFYCONFORMITYOFPRODUCTION
CEC reference fuel RF-03-A-84 (1)(3)(7)
Limits and units ASTM method
Cetan number (4) min 49 D 613
max 53
Density 15 ºC (Kg/l) min 0,835 D 1298
max 0,845
Destillation (2) 50 % min 245 ºC D 86
90 % min 320 ºC
max 340 ºC
FBP max 370 ºC
Flash point min 55 ºC D 93
CFPP min — EN 116 (CEN)
max − 5 ºC
Viscosity 40 ºC min 2,5 mm2/S D 445
max 3,5 mm2/S
Sulphurcontentmin(tobereported)D1266/D2622
D 2785
max 0,05 % mass
Copper corrosion max 1 D 130
Conradson carbon residue (10 % DR) max 0,2 % mass D 189
Ash content max 0,01 % mass D 482
Water content max 0,05 % mass D 95/D 1744
Neutralization (strong acid) number max 0,2 mg KPH/g
Oxidation stability (6) max 2,5 mg/100 m D 2274
Additives (5)
Carbon-hydrogen ratio (to be reported)
(1) Equivalent ISO methods will be adopted when issued all properties listed above.
(2) The figures quoted show the evaporated quantities (percentage recovered + percentage loss).
(3) The values quoted in the specification are ‘true values’. In establishment of their limit values the terms of ASTM
D 3244 ‘Defining a basis for petroleum product quality disputes’ have been applied and in fixing a maximum
value, a minimum difference of 2R above zero has been taken into account; in fixing a maximum and minimumvalue, the minimum difference is 4R (R = reproducibility).
Notwithstanding this measure, which is necessary for statistical reasons, the manufacturer of fuel should
nevertheless aim at a zero value where the stipulated maximum value is 2R and at the mean value in the case ofquotations of maximum and minimum limits. Should it be necessary to clarify the question as to whether a fuelmeets the requirements of the specification, the terms of ASTM D 3244 be applied.
(
4) The range for cetane is note in accordance with the requirement of a minimum range of 4R. However, in cases of
dispute between fuel supplier and fuel user, the terms of ASTM D 3244 can be used to resolve such disputesprovided replicate measurements, of sufficient number to achieve the necessary precision, are made in preferenceto single determinations.
(
5) This fuel should be based on straight run and cracked hydrocarbon distillate components only; desulphurization is
allowed. It must not contain any metallic additives or cetane improver additives.
(6) Even though oxidation stability is controlled, it is likely that shell life will be limited. Advice should be sought
from the supplier as to storage conditions and life.
(7) If it is required to calculate thermal efficiency of an engine or vehicle, the calorific value of the fuel can be
calculated from:
Specific energy (calorific value) (net) MJ/kg =
(46,423−8,792d 2+3,170d)(1−(x+y+s))+9,420s−2,499x
where:d=thedensityat15ºC,
x = the proportion by mass of water (%/100),y = the proportion by mass of ash (%/100),
s = the proportion by mass of sulphur (%/100).1972L0306 — EN — 05.06.1997 — 002.001 — 21
▼M1
▼M2
▼M1
▼B
ANNEX VI
LIMITVALUESAPPLICABLEINTHETESTATSTEADYSPEEDS
NominalflowG
litres/secondAbsorptioncoefficient K
m−1
422·26
45 2·19
502·08
55 1·985
60 1·90
65 1·84
70 1·775
75 1·72
80 1·665
85 1·62
90 1·575
95 1·535
100 1·495
105 1·465
110 1·425
115 1·395
120 1·37
125 1·345130 1·32
135 1·30
140 1·27
145 1·25
150 1·225
155 1·205
160 1·19
165 1·17
170 1·155
175 1·14
180 1·125
185 1·11
190 1·095
1951·08
2001·065
Note: Although the above values are rounded to the nearest 0·01 or 0·005, this
does not mean that the measurements need to be made to this degree of
accuracy.1972L0306 — EN — 05.06.1997 — 002.001 — 22

▼B
ANNEX VII
CHARACTERISTICSOFOPACIMETERS
1. SCOPE
This annex defines the conditions to be met by opacimeters used in the
tests described in Annexes III and IV.
2. BASIC SPECIFICATION FOR OPACIMETERS
2.1. The gas to be measured shall be confined in an enclosure having a non-
reflecting internal surface.
2.2. In determining the effective length of the light path through the gas,
account shall be taken of the possible influence of devices protecting the
light source and the photoelectric cell. This effective length shall be
indicated on the instrument.
2.3. The indicating dial of the opacimeter shall have two measuring scales,
one in absolute units of light absorption from 0 to ∞(m−1) and the other
linear from 0 to 100; both scales shall range from 0 at total light flux to
full scale at complete obscuration.
3. CONSTRUCTION SPECIFICATIONS
3.1.General
The design shall be such that under steady-speed operating conditions
the smoke chamber is filled with smoke of uniform opacity.
3.2.Smokechamberandopacimeter casing
3.2.1. The impingement on the photoelectric cell of stray light due to internal
reflections or diffusion effects shall be reduced to a minimum (e.g. by
finishing internal surfaces in matt black and by a suitable general layout).
3.2.2. The optical characteristics shall be such that the combined effect of
diffusion and reflection does not exceed one unit on the linear scalewhen the smoke chamber is filled with smoke having an absorption
coefficient near 1·7 m
−1.
3.3.Lightsource
The light source shall be an incandescent lamp with a colour temperature
in the range 2 800 to 3 250 ºK.
3.4.Receiver
3.4.1. The receiver shall consist of a photoelectric cell with a spectral response
curve similar to the photopic curve of the human eye (maximum
response in the range 550/570 nm; less than 4 per cent of that maximum
response below 430 nm and above 680 nm).
3.4.2. The construction of the electrical circuit, including the indicating dial,
shall be such that the current output from the photoelectric cell is a linearfunction of the intensity of the light received over the operating-
temperature range of the photoelectric cell.
3.5.Measuringscales
3.5.1. The light-absorption coefficient k shall be calculated by the formula Φ=
Φ
o·e−kL, where L is the effective length of the light path through the gas
to be measured, Φothe incident flux and Φthe emergent flux. When the
effective length L of a type of opacimeter cannot be assessed directly
from its geometry, the effective length L shall be determined
— either by the method described in item 4 of this Annex; or
— through correlation with another type of opacimeter for which the
effective length is known.
3.5.2. The relationship between the 0-100 linear scale and the light absorption
coefficient k is given by the formula
k¼/C01
Llogc1/C0N
100/C18/C191972L0306—EN—05.06.1997—002.001—23
▼B
where N is a reading on the linear scale and k the corresponding value of
the absorption coefficient.
3.5.3. The indicating dial of the opacimeter shall enable an absorption
coefficient of 1·7 m−1to be read with an accuracy of 0·025 m−1.
3.6.Settingandtestingofthemeasuringapparatus
3.6.1. The electrical circuit of the photoelectric cell and of the indicating dial
shall be adjustable so that the pointer can be reset at zero when the light
flux passes through the smoke chamber filled with clean air or through a
chamber having identical characteristics.
3.6.2. With the lamp switched off and the electrical measuring circuit open or
short-circuited, the reading on the absorption-coefficient scale shall be
∞, and it shall remain at ∞with the measuring circuit reconnected.
3.6.3. An intermediate check shall be carried out by placing in the smoke
chamber a screen representing a gas whose known light-absorption
coefficient k, measured as described in item 3.5.1. is between 1·6 m−1and
1·8 m−1. The value of k must be known to within 0·025 m−1. The check
consists in verifying that this value does not differ by more than 0·05 m−1
from that read on the opacimeter indicating dial when the screen isintroduced between the source of light and the photoelectric cell.
3.7.Opacimeter response
3.7.1. The response time of the electrical measuring circuit, being the time
necessary for the indicating dial to reach 90 per cent of full-scale
deflection ►
C2on insertion ◄of a screen fully obscuring the
photoelectric cell, shall be 0·9 to 1·1 second.
3.7.2. The damping of the electrical measuring circuit shall be such that the
initial overswing beyond the final steady reading after any momentary
variation in input (e.g. the calibration screen) does not exceed 4 per cent
of that reading in linear scale units.
3.7.3. The response time of the opacimeter which is due to physical phenomena
in the smoke chamber is the time between the entry of the gas into the
measuring apparatus and the complete filling of the smoke chamber; it
shall not exceed 0·4 second.
3.7.4. These provisions shall apply solely to opacimeters used to measure
opacity under free acceleration.
3.8.Pressureofthegastobemeasuredandofscavengingair
3.8.1. The pressure of the exhaust gas in the smoke chamber shall not differ by
more than 75 mm (water gauge) from the atmospheric pressure.
3.8.2. The variations in the pressure of the gas to be measured and of the
scavenging air shall not cause the absorption coefficient to vary by more
than 0·05 m−1in the case of a gas having an absorption coefficient of 1·7
m−1.
3.8.3. The opacimeter shall be equipped with appropriate devices for measuring
the pressure in the smoke chamber.
3.8.4. The limits of pressure variation of gas and scavenging air in the smoke
chamber shall be indicated by the manufacturer of the apparatus.
3.9.Temperatureofthegastobemeasured
3.9.1. At every point in the smoke chamber the gas temperature at the instant of
measurement shall be between 70 ºC and a maximum temperature,
specified by the opacimeter manufacturer, such that the readings over
this temperature range do not vary by more than 0·1 m−1if the chamber is
filled with a gas having an absorption coefficient of 1·7 m−1.
3.9.2. The opacimeter shall be equipped with appropriate devices for measuring
the temperature in the smoke chamber.
4. EFFECTIVE LENGTH ‘L’ OF THE OPACIMETER
4.1.General
4.1.1. In some types of opacimeter the gas between the light source and the
photoelectric cell, or between transparent parts protecting the source and
the photoelectric cell, is not of constant opacity. In such cases the
effective length L shall be that of a column of gas of uniform opacity1972L0306 — EN — 05.06.1997 — 002.001 — 24
▼B
which gives the same absorption of light as that obtained when the gas is
admitted in a normal way into the opacimeter.
4.1.2. The effective length of the light path is obtained by comparing the
reading N of the opacimeter operating normally with the reading Noobtained with the opacimeter modified so that the test gas fills a welldefined length L
o.
4.1.3. It will be necessary to take comparative readings in quick succession to
determine the correction to be made for shifts of zero.
4.2.MethodofassessmentofL
4.2.1. The test gas shall be exhaust gas of constant opacity or a light-absorptive
gas of a gravimetric density similar to that of the exhaust gas.
4.2.2. A column of length Loof the opacimeter, which can be filled uniformly
with the test gases, and the ends of which are substantially at right anglesto the light path, shall be accurately determined. This length L
oshall be
close to the presumed effective length of the opacimeter.
4.2.3. The mean temperature of the test gas in the smoke chamber shall be
measured.
4.2.4. If necessary, an expansion tank of compact design and of sufficient
capacity to damp the pulsations may be incorporated in the sampling line
as near to the probe as possible. A cooler may also be fitted. The addition
of the expansion tank and of the cooler must not unduly disturb the
composition of the exhaust gas.
4.2.5. The test for determining the effective length shall consist of passing a
sample of test gas alternately through the opacimeter operating normally
and through the same apparatus modified as indicated in item 4.1.2.
4.2.5.1. The opacimeter readings shall be recorded continuously during the test
with a recorder whose response time is equal to or shorter than that of the
opacimeter.
4.2.5.2. With the opacimeter operating normally, the reading on the linear scale
of opacity is N and that of the mean gas temperature expressed in Kelvindegrees is T.
4.2.5.3. With the known length L
ofilled with the same test gas, the reading on the
linear scale of opacity is Noand that of the mean gas temperature
expressed in Kelvin degrees is To.
4.2.6. The effective length will be
4.2.7. The test shall be repeated with at least four test gases giving readings
evenly spaced between the 20 and 80 on the linear scale.
4.2.8. The effective length L of the opacimeter will be the arithmetic mean of
the effective lengths obtained as stated in item 4.6 with each of the gases.1972L0306 — EN — 05.06.1997 — 002.001 — 25

▼B
ANNEXVIII
INSTALLATIONANDUSEOFTHEOPACIMETER
1. SCOPE
This annex specifies the installation and use of opacimeters for the tests
described in Annexes III and IV.
2. SAMPLING OPACIMETER
2.1.Installationforsteady-speedtests
2.1.1. The ratio of the cross-sectional area of the probe to that of the exhaust pipe
shall not be less than 0·05. The back pressure measured in the exhaust pipe
at the intake of the probe shall not exceed 75 mm (water gauge).
2.1.2. The probe shall be a tube with an open end facing forwards in the axis of
the exhaust pipe, or of the extension pipe if one is required. It shall he
situated in a section where the distribution of smoke is approximately
uniform. To achieve this, the probe shall be placed as far downstream in
the exhaust pipe as possible, or, if necessary, in an extension pipe so that,
if D is the diameter of the exhaust pipe at the outlet, the end of the probe is
situated in a straight portion at least 6 D in length upstream of the sampling
point and 3 D in length downstream. If an extension pipe is used, no air
shall be allowed to enter the joint.
2.1.3. The pressure in the exhaust pipe and the characteristics of the pressure
drop in the sampling line shall be such that the probe collects a sample
substantially equivalent to that which would be obtained by isokinetic
sampling.
2.1.4. If necessary, an expansion tank of compact design and of sufficient
capacity to damp the pulsations may be incorporated in the sampling line
as near to the probe as possible. A cooler may also be fitted.
The design of the expansion tank and cooler shall not unduly disturb the
composition of the exhaust gas.
2.1.5. A butterfly valve or other means of increasing the sampling pressure may
be placed in the exhaust pipe at least three 3 D downstream from the
sampling probe.
2.1.6. The connecting pipes between the probe, the cooling device, the expansion
tank (if required) and the opacimeter shall be as short as possible while
satisfying the pressure and temperature requirements described in Annex
VII, items 3.8 and 3.9. The pipe shall be inclined upwards from the
sampling point to the opacimeter, and sharp bends where soot might
accumulate shall be avoided. If not embodied in the opacimeter, a bypass
valve shall be provided upstream.
2.1.7. A check shall be carried out during the test to ensure that the requirements
of Annex VII, item 3.8, concerning pressure and those of Annex VII, item
3.9, concerning the temperature in the measuring chamber are observed.
2.2.Installationfortestsunderfree acceleration
2.2.1. The ratio of the cross-sectional area of the probe to that of the exhaust pipe
shall not be less thas 0·05. The back pressure measured in the exhaust pipe
at the intake of the probe shall not exceed 75 mm (water gauge).
2.2.2. The probe shall be a tube with an open end facing forwards in the axis of
the exhaust pipe, or of the extension pipe if one is required. It shall be
situated in a section where the distribution of smoke is approximately
uniform. To achieve this, the probe shall be placed as far downstream in
the exhaust pipe as possible or, if necessary, in an extension pipe so that, if
D is the diameter of the exhaust pipe at the outlet, the end of the probe is
situated in a straight portion at least 6 D in length upstream of the sampling
point and 3 D in length downstream. If an extension pipe is used, no air
shall be allowed to enter the joint.
2.2.3. The sampling system shall be such that at all engine speeds the pressure of
the sample at the opacimeter is within the limits specified in Annex VII,
item 3.8.2. This may be checked by noting the sample pressure at engine
idling and maximum no-load speeds. Depending on the characteristics of
the opacimeter, control of sample pressure can be achieved by a fixed
restriction or a butterfly valve in the exhaust pipe or extension pipe.1972L0306 — EN — 05.06.1997 — 002.001 — 26
▼B
Whichever method is used, the back pressure measured in the exhaust pipe
at the intake of the probe shall not exceed 75 mm (water gauge).
2.2.4. The pipes connecting with the opacimeter shall be as short as possible. The
pipe shall be inclined upwards from the sampling point to the opacimeter,
and sharp bends where soot might accumulate shall be avoided. A bypass
valve may be provided upstream of the opacimeter to isolate it from the
exhaust-gas flow when no measurement is being made.
3. FULL-FLOW OPACIMETER
The only general precautions to be observed in steady-speed and free-
acceleration tests are the following:
3.1. Joints in the connecting pipes between the exhaust pipe and the opacimeter
shall not allow air to enter from outside.
3.2. The pipes connecting with the opacimeter shall be as short as possible, as
in the case of sampling opacimeters. The pipe system shall be inclined
upwards from the exhaust pipe to the opacimeter, and sharp bends where
soot might accumulate shall be avoided. A bypass valve may be provided
upstream of the opacimeter to isolate it from the exhaust-gas flow when no
measurement is being made.
3.3. A cooling system may also he required upstream of the opacimeter.1972L0306 — EN — 05.06.1997 — 002.001 — 27
▼M2