This document is meant purely as documentation tool and the institutions do not assume any liability for its contents
"BCOUNCIL DIRECTIVE
of 28 June 1977
on the approximation of the laws of the Member States relating to the measures to be taken against
the emission of pollutants from diesel engines for use in wheeled agricultural or forestry tractors
(77/537/EEC)
(OJ L 220, 29.8.1977, p. 38)
Amended by:
Official Journal
No page date
"M1 Council Directive 82/890/EEC of 17 December 1982 L 378 45 31.12.1982
"M2 Directive 97/54/EC of the European Parliament and of the Council
of 23 September 1997L 277 24 10.10.19971977L0537 — EN — 30.10.1997 — 002.001 — 1
COUNCIL DIRECTIVE
of 28 June 1977
on the approximation of the laws of the Member States relating to
the measures to be taken against the emission of pollutants from
diesel engines for use in wheeled agricultural or forestry tractors
(77/537/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 (
1),
Having regard to the opinion of the Economic and Social Committee (2),
Whereas the technical requirements which tractors must satisfy pursuant
to national laws relate inter alia to the emission of pollutants from diesel
engines for use in tractors;
Whereas those requirements differ from one Member State to another;
whereas it is therefore necessary that all the Member States adopt the
same 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 Council Directive 74/150/EEC of 4 March 1974 on the
approximation of the laws of the Member States relating to the
type-approval of wheeled agricultural or forestry tractors (3), to be
applied in respect of each type of tractor;
Whereas the approximation of national laws relating to tractors entails
reciprocal recognition by Member States of the tests carried out by each
of them on the basis of common requirements,
HAS ADOPTED THIS DIRECTIVE:
Article 1
1. ‘Agricultural or forestry tractor’ means any motor vehicle, fitted
with wheels or endless tracks, having at least two axles, the main
function of which lies in its tractive power and which is specially
designed to tow, push, carry or power certain tools, machinery or trailers
intended for agricultural or forestry use. It may be equipped to carry a
load and passengers.
2. This Directive shall apply only to tractors defined in paragraph I
which are equipped with pneumatic tyres and have at least two axles and
a maximum design speed of between 6 and "M240 km/h 3.
Article 2
No Member State may refuse to grant a tractor EEC type-approval or
national type-approval on the grounds that pollutants are emitted by the
diesel engine which drives the tractor if the tractor satisfies the
requirements laid down in Annexes I, II, III, IV and VI.!B
(1) OJ No C 125, 8. 6. 1976, p. 51.
(2) OJ No C 197, 23. 8. 1976, p. 16.
(3) OJ No L 84, 28. 3. 1974, p. 10.!M1
!B1977L0537 — EN — 30.10.1997 — 002.001 — 2
Article 3
No Member State may refuse the registration or may prohibit the sale,
entry into service or use of any tractor on the grounds that pollutants are
emitted by the diesel engine which drives the tractor if the tractor
satisfies the requirements laid down in Annexes I, II, III, IV and VI.
Article 4
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 2.2 of Annex I. The competent
authorities of that State shall determine whether fresh tests should be
carried out on the modified tractor and a fresh report drawn up. Where
such tests reveal a failure to comply with the requirements of this
Directive, the modification shall not be approved.
Article 5
The amendments necessary to adapt the provisions of Annexes I to X to
this Directive to take account of technical progress shall be adopted in
accordance with the procedure laid down in Article 13 of Directive
74/150/EEC.
Article 6
1. Member States shall bring into force provisions containing the
provisions necessary in order to comply with this Directive within 18
months of its notification and shall forthwith inform the Commission
thereof.
2. Member States shall ensure that the texts of the main provisions of
national law which they adopt in the field covered by this Directive are
communicated to the Commission.
Article 7
This Directive is addressed to the Member States.!B1977L0537 — EN — 30.10.1997 — 002.001 — 3
ANNEX I (1)
DEFINITIONS, APPLICATION FOR EEC TYPE-APPROV AL, SYMBOL
OF THE CORRECTED ABSORPTION COEFFICIENT,
SPECIFICATIONS AND TESTS AND CONFORMITY OF PRODUCTION
(1.)
2. DEFINITIONS
For the purposes of this Directive:
(2.1.)
2.2. ‘ tractor type as regards the limitation of the emission of pollutants from
the engine ’ means tractors which do not differ in such essential respects
as the tractor and engine characteristics defined in Annex II;
2.3. ‘ diesel engine ’ means an engine which works on the compression-
ignition principle;
2.4. ‘ cold-start device ’ means a device which by its operation temporarily
increases the amount of fuel supplied to the engine and is intended tofacilitate the starting of the engine;
2.5. ‘ opacimeter ’ means an instrument for continuous measurement of the
absorption coefficients of the light by the exhaust gases emitted bytractors.
3. APPLICATION FOR EEC TYPE-APPROV AL
3.1. The application for approval must be sub mitted by the tractor
manufacturer or by his duly accredited representative.
3.2. It must be accompanied by the undermentioned documents in triplicate
and the following particulars:
3.2.1. a description of the engine type including all the particulars referred to in
Annex II;
3.2.2. drawings of the combustion chamber and of the upper face of the piston.
3.3. An engine and the equipment prescribed in Annex II to this Regulation,
for fitting to the tractor to be approved, shall be submitted to the technicalservice conducting the approval tests defined in 5. However, if the
manufacturer so requests and the technical service conducting the
approval tests agrees, a test may be carried out on a tractor representativeof the tractor type to be approved.
3a. EEC TYPE-APPROV AL
A certificate conforming to that shown in Annex X shall be attached to
the EEC type-approval certificate.
4. SYMBOL OF THE CORRECTED ABSORPTION COEFFICIENT(4.1.)(4.2.)(4.3.)
4.4. To every tractor conforming to a tractor type approved under this
Regulation there shall be affixed, conspicuously and in a readily
accessible place specified in the Annex to the type-approval certificate
shown in Annex X, a symbol being a rectangle surrounding a figureexpressing in m
−1the corrected absorption coefficient obtained, at the
time of approval, during the test under free acceleration, and determined
at the time of approval by the method described in 3.2 of Annex IV .
4.5. The symbol must be clearly legible and indelible.!B
(1) The text of the Annexes is similar to that of Regulation No 24 of the UN Economic
Commission for Europe; in particular the breakdown into items is the same. For this
reason, where an item of Regulation No 24 has no counterpart in this Directive, its
number is given in brackets as a token entry.1977L0537 — EN — 30.10.1997 — 002.001 — 4
4.6. Annex IX gives an example of the symbol.
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 tractor in normal
use, despite the vibration to which it may be subjected, to comply with the
provisions of this Directive.
5.2. Specifications concerning cold-start devices
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 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 withthe cold-start device operating is within the limits prescribed in AnnexVI;
5.2.2.2. keeping the cold-start device in operation causes the engine to stop within
a reasonable time.
5.3. Specifications concerning the emission of pollutants
5.3.1. The emission of pollutants by the tractor 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 (
1).
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 steadyspeeds, plus 0.5m
−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.)
7. CONFORMITY OF PRODUCTION
7.1. Every tractor in the series must conform, with regard to components
affecting the emission of pollutants by the engine, to the tractor typeapproved.)
(7.2.)
7.3. As a general rule conformity of the tractor with the approved type as
regards the emission of pollutants from diesel motors shall be verified onthe basis of the description given in the Annex to the EEC approval
certificate shown in Annex X. In addition:
7.3.1. where a check is carried out on a vehicle taken from the series, the tests
shall be carried out as follows:
7.3.1.1. a tractor 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 determineddoes not exceed the figure shown in the approval mark by more than 0.5
m
−1;
7.3.1.2. if the figure determined in the test referred to in 7.3.1.1 above exceeds the
figure shown in the approval mark by more than 0.5m−1, a tractor of the
type considered or its engine shall be subjected to the test at steady!B
(1) A test under free acceleration shall be carried out, particularly in order to provide a
reference figure for administrations which use this method to check vehicles in use.1977L0537 — EN — 30.10.1997 — 002.001 — 5
speeds as described in Annex III. The emission levels shall not exceed the
limits prescribed in Annex VI.
(8.)
(9.)!B1977L0537 — EN — 30.10.1997 — 002.001 — 6
ANNEX II
!B1977L0537 — EN — 30.10.1997 — 002.001 — 7
!B1977L0537 — EN — 30.10.1997 — 002.001 — 8
!B1977L0537 — EN — 30.10.1997 — 002.001 — 9
ANNEX III
TEST AT STEADY SPEEDS
1. INTRODUCTION
1.1. This Annex describes the method of determining emissions of pollutants
at different steady speeds at 80% of the maximum load.
1.2. The test may be carried out either on an engine or on a tractor.
2. MEASUREMENT PRINCIPLE
2.1. The opacity of the exhaust gases produced by the engine shall be
measured with the engine running under 80% of the maximum load and
at steady speed. Six measurements shall be made at engine speeds spacedout uniformly between that corresponding to maximum power and thehigher of the following two engine speeds:
— 55% 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 intooperation 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 CONDITIONS
3.1. Tractor or engine
3.1.1. The engine or the tractor 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 Annex II.
3.1.3. The settings of the engine shall be those described by the manufacturer
and by Annex II.
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 atthe 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. Test laboratory
3.3.1. The absolute temperature T of the laboratory, expressed in Kelvin, and
the atmospheric pressure H, expressed in torr, shall be measured, and thefactor F shall be determined by the formula
F¼750
H/C18/C19
0/C165/C2T
298/C18/C19
0/C15
3.3.2. For a test to be recognized as valid, the factor F shall be such that 0.984
F41.02.
3.4. Sampling and measuring apparatus
The light-absorption coefficient of the exhaust gases shall be measured
with an opacimeter satisfying the conditions laid down in Annex VII andinstalled in conformity with Annex VIII.!
B1977L0537 — EN — 30.10.1997 — 002.001 — 10
4. LIMIT V ALUES
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:
— for two-stroke engines
G¼Vn
60
— for four-stroke engines G¼Vn
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 ofproportional parts.!
B1977L0537 — EN — 30.10.1997 — 002.001 — 11
ANNEX IV
TEST UNDER FREE ACCELERATION
1. TEST CONDITIONS
1.1. The test shall be carried out on the tractor 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 at steady speed. Inparticular, the cooling water and the oil shall be at the normaltemperatures indicated by the manufacturer.
1.1.2. If the test is carried out on a stationary tractor, 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 3.1, 3.2 and 3.3 of Annex III shall apply.
1.4. The conditions described in 3.4 of Annex III, 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 gearis engaged or by an inertia substantially equivalent to that of the rotatingparts.
2.2. If the test is carried out on a tractor, 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 injectionpump. 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 itsidling speed and the opacimeter reverts to the corresponding conditions.
2.4. The operation described in 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 idlingafter 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 f itted 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 becarried 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 driveroperated 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 V ALUE OF THE AB-
SORPTION COEFFICIENT
3.1. Notation
X
M= value of the absorption coefficient under free acceleration
measured as described in 2.4 of this Annex;
XL= corrected value of the absorption coefficient under free acceler-
ation;!B1977L0537 — EN — 30.10.1997 — 002.001 — 12
SM= value of the absorption coefficient measured at steady speed (2.1
of Annex III), which is closest to the prescribed limit value
corresponding to the same nominal flow;
SL= value of the absorption coefficient (4.2 of Annex III) for the
nominal flow corresponding to the point of measurement which
gave the value S M;
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 correcte value X Lis given by the
smaller of the following two expressions:
X0
L¼SL
SM/C2XMorX00
L¼XMþ0/C15!B1977L0537 — EN — 30.10.1997 — 002.001 — 13
ANNEX V
SPECIFICATIONS OF REFERENCE FUEL PRESCRIBED FOR APPROV AL TESTS AND TO VERIFY
CONFORMITY OF PRODUCTION
Limits and units Method
Density 15/4 °C 0.830±0.005 ASTM D 1298-67
Distillation ASTM D 86-67
50 % min. 245 °C
90 % 330 ± 10 °C
Final boiling point max. 370 °C
Cetane index 54 ± 3 ASTM D 976-66
Kinematic viscosity at 100 °F 3 ± 0.5cSt ASTM D 445-65
Sulphur content 0.4±0.1% by weight ASTM D 129-64
Flash-point min. 55 °C ASTM D 93-71
Cloud point max. − 7 °C ASTM D 2500-66
Aniline point 69 ± 5 °C ASTM D 611-64
Carbon residue on 10 % bottoms max. 0.2% by weight ASTM D 524-64
Ash content max. 0.01 % by weight ASTM D 482-63
Water content max. 0.05 % by weight ASTM D 95-70
Copper — corrosion test at 100 °C max. 1 ASTM D 130-68
Net calorific value
 ASTM D 2-68
(Ap. VI)
Strong acid number nil mg KOH/g ASTM D 974-64
Note: The fuel must be based only on straight-run distillates, hydrodesulphurized or not, and must contain no additives.!B1977L0537 — EN — 30.10.1997 — 002.001 — 14
ANNEX VI
LIMIT V ALUES APPLICABLE IN THE TEST AT STEADY SPEEDS
Nominal flow G
litres/secondAbsorptions coefficient k
m−1
442 2.26
45 2.19
50 2.08
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 1.345
130 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
195 1.08
5200 1.065
Note: Although the above values are rounded to the nearest 0.01or 0.005, this
does not mean that the measurements need to be made to this degree of
accuracy.!B1977L0537 — EN — 30.10.1997 — 002.001 — 15
ANNEX VII
CHARACTERISTICS OF OPACIMETERS
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 SPECIFICATIONS3.1. General
The design shall be such that under steady-speed operating conditions the
smoke chamber is filled with smoke of uniform opacity.
3.2. Smoke chamber and opacimeter 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. byfinishing 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 scale when
the smoke chamber is filled with smoke having an absorption coefficientnear 1.7m
−1.
3.3. Light source
The light source shall be an incandescent lamp with a colour temperature
in the range 2 800 to 3 250 K.
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 % 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-tempera-
ture range of the photoelectric cell.
3.5. Measuring scales
3.5.1. The light-absorption coefficient k shall be calculated by the formula
Φ¼Φo/C1e/C0kL, 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 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 to 100 linear scale and the light absorption
coefficient k is given by the formula
k¼/C01
Lloge1/C0N
100/C18/C19!B1977L0537 — EN — 30.10.1997 — 002.001 — 16
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 1.7m−1to be read with an accuracy of 0.025m−1.
3.6. Setting and testing of the measuring apparatus
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 achamber 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-absorptioncoefficient k, measured as described in 3.5.1, is between 1.6m
−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 0.05m−1
from that read on the opacimeter indicating dial when the screen is
introduced 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 % of full-scale deflection on
insertion of a screen fully obscuring the photoelectric cell, shall be 0.9to
1.1seconds.
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 % 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 beginning of the entry of
the gas into the measuring apparatus and the complete filling of the
smoke chamber; it shall not exceed 0.4second.
3.7.4. These provisions shall apply solely to opacimeters used to measure
opacity under free acceleration.
3.8. Pressure of the gas to be measured and of scavenging air
3.8.1. The pressure of the exhaust gas in the smoke chamber shall not differ by
more than 735 Pa 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 morethan 0.05m
−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. Temperature of the gas to be measured
3.9.1. At every point in the smoke chamber the gas temperature at the instant of
measurement shall be between 70 °C and a maximum temperature,
specified by the opacimeter manufacturer, such that the readings over this
temperature range do not vary by more than 0.1m−1if the chamber is
filled with a gas having an absorption coefficient of 1.7m−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 OPACIMETER4.1. 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 andthe photoelectric cell, is not of constant opacity. In such cases the
effective length L shall be that of a column of gas of uniform opacity
which gives the same absorption of light as that obtained when the gas isadmitted in a normal way into the opacimeter.!
B1977L0537 — EN — 30.10.1997 — 002.001 — 17
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 N o
obtained 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. Method of assessment of L
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 L oof the opacimeter, which can be filled uniformly
with the test gases, and the ends of which are substantially at right angles
to 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 lineas 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 normallyand through the same apparatus modified as indicated in 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 theopacimeter.
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 Kelvin 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 N oand that of the mean gas temperature
expressed in Kelvin is T o.
4.2.6. The effective length will be
L¼LoT
Tolog 1 /C0N
100/C16/C17
log 1 /C0No
100/C16/C17
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 4.2.6 with each of the gases.!B1977L0537 — EN — 30.10.1997 — 002.001 — 18
ANNEX VIII
INSTALLATION AND USE OF THE OPACIMETER
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. Installation for steady-speed tests
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 735 Pa.
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 besituated 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 probeis 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 isokineticsampling.
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 lineas near to the probe as possible. A cooler may also be fitted. The addition
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 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 requirementsdescribed in 3.8 and 3.9 of Annex VII. The pipe shall be inclined upwardsfrom 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 3.8 of Annex VII, concerning pressure and those of3.9 of Annex VII, concerning the temperature in the measuring chamber,are observed.
2.2. Installation for tests under free acceleration
2.2.1. 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 735 Pa.
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 besituated in a section where the distribution of smoke is approximatelyuniform. 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 probeis situated in a straight portion at least 6 D in length upstream of thesampling 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 3.8.2 of
Annex VII. This may be checked by noting the sample pressure at engineidling and maximum no-load speeds. Depending on the characteristics ofthe opacimeter, control of sample pressure can be achieved by a fixed
restriction or a butterfly valve in the exhaust pipe or extension pipe.
Whichever method is used, the back pressure measured in the exhaustpipe at the intake of the probe shall not exceed 735 Pa.!
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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 toisolate 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 providedupstream of the opacimeter to isolate it from the exhaust-gas flow whenno measurement is being made;
3.3. a cooling system may also be required upstream of the opacimeter.!
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ANNEX IX
EXAMPLE OF THE SYMBOL OF THE CORRECTED ABSORPTION COEFFICIENT
The above symbol shows that the corrected absorption coefficient is 1.30m−1.!B1977L0537 — EN — 30.10.1997 — 002.001 — 21
ANNEX X
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