Date: 2018-11-16Category: Not ApplicableState: Union GovernmentCountry: Europe
Regulation No 92 of the Economic Commission for Europe of the United Nations (UNECE) — Uniform provisions concerning the approval of non-original replacement exhaust silencing systems (NORESS) for vehicles of categories L1, L2, L3, L4 and L5 with regard to sound emission [2018/1707]
Executive Summary:
This document outlines the UNECE Regulation No. 92 concerning the approval of non-original replacement exhaust silencing systems (NORESS) for specific vehicle categories (L1, L2, L3, L4, and L5) regarding sound emission. It incorporates all valid text up to Supplement 2 to the 01 series of amendments, with a date of entry into force of 10 October 2017. The regulation details the scope, definitions, application process, markings, specifications, and conformity of production for NORESS.
Key Points / Main Content:
* **Scope:**
* Applies to non-original replacement exhaust silencing systems for vehicles of categories L1, L2, L3, L4, and L5.
* **Definitions:**
* Defines "non-original replacement exhaust silencing system" (NORESS) as a system different from the original, used only as a replacement.
* Specifies components of the exhaust silencing system, including the exhaust manifold, silencer, expansion chamber, and resonator.
* Clarifies "vehicle type" based on engine, drive train, and exhaust system characteristics.
* Defines "rated engine speed".
* **Application for Approval:**
* The manufacturer or representative must submit the application.
* Requires triplicate documentation, including vehicle type description, NORESS description, assembly instructions, and detailed drawings.
* Technical Services may request NORESS samples, original exhaust systems, and representative test vehicles.
* Specifies sound level conditions for test vehicles, not exceeding original limits by more than 1 dBA during motion or 3 dBA during stationary tests.
* **Markings:**
* Each NORESS component must bear the manufacturer's trade name/mark and commercial designation.
* Markings must be legible, indelible, and visible after fitting.
* NORESS must be labeled with approved vehicle types.
* Packaging/labeling must include manufacturer details and intended vehicle models.
* Manufacturers must provide detailed mounting and handling instructions, plus a parts list.
* **Approval:**
* Approval is granted if the NORESS meets specifications.
* Each approved NORESS type receives a unique approval number.
* Notification of approval, extension, or refusal is communicated to relevant parties.
* An international approval mark must be affixed, including the "E" mark and approval number.
* **Specifications:**
* General specifications address vehicle compliance, corrosion resistance, ground clearance, surface temperature, and safety.
* Acoustic efficiency is verified using methods from Regulations Nos. 9, 41, or 63, ensuring sound levels do not exceed original system levels.
* Tampering protection: NORESS shall not permit removal of internal parts and defeat devices are prohibited.
* Multi-mode NORESS must meet all requirements in all modes, with the highest sound level reported.
* Additional Sound Emission Provisions (ASEP) from Regulation No. 41 must be met for vehicles type-approved to the 04 series of amendments.
* Performance must be comparable to the original system, with maximum power and engine speed not exceeding the original by more than 5%.
* Specifies engine and vehicle test methods for performance verification.
* Fibrous materials are permitted if they meet specific requirements outlined in Annex 3.
* Pollution requirements according to vehicle type approval must be fulfilled.
* **Modification and Extension of Approval:**
* Modifications must be reported to the Type Approval Authority, which may require further testing.
* Manufacturers can request extensions of approval to other vehicle types.
* Confirmation or refusal of approval, detailing modifications, will be communicated.
* **Conformity of Production:**
* Procedures must comply with Agreement Appendix 2 EECE324EECETRANS505Rev.2.
* NORESS must conform to the approved type and meet the specified requirements.
* Approval holders must conduct tests as prescribed in paragraph 6.
* Authorities can verify conformity control methods.
* **Penalties for Nonconformity:**
* Approval can be withdrawn if requirements are not met or tests are failed.
* Contracting Parties must notify others of approval withdrawals.
* **Production Discontinuation:**
* The approval holder must inform the authority of production cessation, which then informs other Contracting Parties.
* **Technical Services and Approval Authorities:**
* Contracting Parties must communicate the names and addresses of Technical Services and Type Approval Authorities to the United Nations Secretariat.
Impact Analysis:
* **NORESS Manufacturers:**
* Impact: Must adhere to design, marking, and performance specifications; undergo approval processes; and ensure conformity of production.
* Action Required: Implement procedures to meet all requirements for design, testing, and manufacturing; prepare and submit applications for approval; maintain conformity of production.
* **Type Approval Authorities:**
* Impact: Responsible for evaluating NORESS applications, conducting tests, granting approvals, and monitoring conformity of production.
* Action Required: Establish processes for receiving and evaluating applications; conduct necessary tests; issue approvals; monitor production conformity.
* **Technical Services:**
* Impact: Conduct tests to verify NORESS compliance with the regulation.
* Action Required: Perform tests as requested by Type Approval Authorities; provide accurate and thorough test reports.
* **Vehicle Manufacturers:**
* Impact: Need to ensure that NORESS fitted as replacements do not negatively impact vehicle performance or exceed sound emission limits.
* Action Required: Verify that replacement NORESS meet regulatory requirements; provide information to customers regarding approved NORESS options.
* **Consumers:**
* Impact: Affected by the availability of compliant replacement exhaust systems and the assurance that these systems meet sound emission standards and maintain vehicle performance.
* Action Required: Choose approved NORESS for their vehicles.
Key Entities Referenced
UNECE: United Nations Economic Commission for Europe. Sets standards for vehicle regulations.
Regulation No 92: UNECE regulation concerning the approval of non-original replacement exhaust silencing systems (NORESS) for vehicles of categories L1, L2, L3, L4 and L5 with regard to sound emission.
NORESS: Non-Original Replacement Exhaust Silencing System. A replacement exhaust system that is not the original equipment.
Regulation No 9: UNECE Regulation on Uniform provisions concerning the approval of vehicles with regard to sound emissions.
Regulation No 41: UNECE Regulation concerning the approval of motorcycles with regard to noise.
Regulation No 63: UNECE Regulation relating to the approval of mopeds with regard to noise.
Type Approval Authority: Authority responsible for granting type approval for vehicle components.
Technical Service: Technical Services responsible for conducting approval tests.
L 290/162 EN Official Journal of the European Union 16.11.2018
Only the original UN/ECE texts have legal effect under international public law. The status and date of entry into force of this Regulation
should be checked in the latest version of the UN/ECE status document TRANS/WP.29/343, available at:
http://www.unece.org/trans/main/wp29/wp29wgs/wp29gen/wp29fdocstts.html
Regulation No 92 of the Economic Commission for Europe of the United Nations (UNECE) —
Uniform provisions concerning the approval of non-original replacement exhaust silencing
systems (NORESS) for vehicles of categories L , L , L , L and L with regard to sound emission
1 2 3 4 5
[2018/1707]
Incorporating all valid text up to:
Supplement 2 to the 01 series of amendments – Date of entry into force: 10 October 2017
CONTENTS
REGULATION
1. Scope
2. Definitions
3. Application for approval
4. Markings
5. Approval
6. Specifications
7. Modification and extension of the approval of NORESS and extension of approval
8. Conformity of production
9. Penalties for non-conformity of production
10. Production definitively discontinued
11. Names and addresses of Technical Services responsible for conducting approval tests, and of Type Approval
Authorities
Annexes
1. Communication
2. Example of the approval marks
3. Requirements for fibrous absorbent materials used in NORESS
4. Statement of Compliance with the Additional Sound Emission Provisions
1. SCOPE
This Regulation applies to non-original replacement exhaust silencing systems for vehicles of categories L , L
1 2,
L L and L (1).
3, 4 5
2. DEFINITIONS
For the purpose of this Regulation
2.1. ‘Non-original replacement exhaust silencing system or components of this system’ means a system of a type
different from that fitted to the vehicle on approval or extension of approval. It may be used only as
a replacement exhaust or silencing system.
The acronym NORESS denotes the non-original replacement exhaust silencing system.
2.2. ‘Non-original replacement exhaust silencing system component’ means one of the various components which
together form the exhaust silencing system (2);
(1) As defined in the Consolidated Resolution on the Construction of Vehicles (R.E.3.), document ECE/TRANS/WP.29/78/Rev.4, para. 2 -
www.unece.org/trans/main/wp29/wp29wgs/wp29gen/wp29resolutions.html
(2) Those components are, in particular, the exhaust manifold, the silencer proper, the expansion chamber and the resonator16.11.2018 EN Official Journal of the European Union L 290/163
2.3. ‘Non-original replacement exhaust silencing systems of different types’ means silencing systems which differ sig
nificantly in such respects as:
(a) Their components bear different trade names or marks,
(b) The characteristics of the materials constituting a component are different or the components differ in
shape or size; a modification in respect to coating (zinc coating, aluminium coating, etc.) is not considered
a change of type,
(c) The operating principles of at least one component are different,
(d) Their components are combined differently;
2.4. ‘Non-original replacement exhaust silencing system (NORESS) or component thereof’ means any part of the
exhaust silencing system defined in paragraph 2.1 intended for use on a vehicle other than a part of the type
fitted to the vehicle when submitted for type approval pursuant to Regulation No 9, Regulation No 41 or
Regulation No 63;
2.5. ‘Approval of a NORESS or component(s) thereof’ means the approval of the whole or a part of a silencing
system adaptable to one or several specified types of vehicle, falling under the scope of this Regulation, as
regards the limitation of their sound level;
2.6. ‘Vehicle type’ means vehicles, falling under the scope of this Regulation, which do not differ in such essential
respects as:
(a) The type of engine (two-stroke or four-stroke with reciprocating or rotary pistons; number and capacity of
cylinders; number and type of carburettors or injection systems; arrangement of valves; maximum net
power and corresponding engine speed). For rotary piston engines, the cubic capacity should be taken to
be double of the volume of the chamber;
(b) Drive train, in particular the number and ratios of the gears of the transmission and the final ratio;
(c) Number, type and arrangement of exhaust silencing systems.
2.7. ‘Rated engine speed’ means the engine speed at which the engine develops its rated maximum net power as
stated by the manufacturer (1).
The symbol n denotes the numerical value of the rated engine speed expressed in revolutions per minute.
rated
3. APPLICATION FOR APPROVAL
3.1. The application for approval of a NORESS or components thereof shall be submitted by its manufacturer or by
his duly accredited representative.
3.2. It shall be accompanied by the under mentioned documents in triplicate and the following particulars:
(a) A description of the vehicle type(s) on which the NORESS or components are intended to be fitted, with
regard to the items referred to in paragraph 2.6 above. The numbers and/or symbols identifying the engine
type and the vehicle type shall be specified and the vehicle type approval number, if necessary;
(b) A description of the complete NORESS showing the relative position of each of its components, together
with instructions for their assembly;
(c) Detailed drawings of each NORESS component to enable it to be easily located and identified, and specifi
cation of the materials used. These drawings shall also indicate the location for the mandatory affixing of
the approval number.
3.3. At the request of the Technical Service conducting the tests for approval, the manufacturer of the NORESS
shall submit:
(a) Two samples of the NORESS or its components submitted for approval;
(b) A sample of the original exhaust silencing system with which the vehicle was equipped when submitted for
type approval;
(1) If the rated maximum net power is reached at several engine speeds, the rated engine speed is used in this Regulation as the highest
engine speed at which the rated maximum net power is reached.L 290/164 EN Official Journal of the European Union 16.11.2018
(c) A test vehicle representative of the type to which the NORESS is to be fitted; this vehicle, when measured
for sound emission according to the methods described in Annex 3 (including all relevant amendments) to
Regulation No 9, Regulation No 41 or Regulation No 63 shall satisfy the following conditions:
(i) If the vehicle is of a type for which approval has been issued pursuant to the requirements of each of
Regulations Nos 9, 41 or 63:
(a) The sound level, during the test in motion shall not exceed the limit specified in the appropriate
Regulation by more than 1 dB(A);
(b) The sound level during the stationary test shall not exceed by more than 3 dB(A), the level
determined during the approval and indicated on the manufacturer's plate.
(ii) If the vehicle is not of the type for which approval has been issued pursuant to the requirements of the
appropriate Regulation, the sound level shall not exceed by more than 1 dB(A) the limit applicable at
the time when it was first put on the road.
4. MARKINGS
4.1. Each component of the NORESS, excluding pipes and fitting accessories, shall bear:
(a) The trade name or mark of the manufacturer of the NORESS of its components;
(b) The commercial designation given by the manufacturer.
4.2. These markings shall be clearly legible and indelible and also visible in the position at which the NORESS is
fitted.
4.3. The NORESS shall be labelled by its manufacturer; indicating the type(s) of vehicle(s) for which it has been
granted the approval.
4.4. A component may carry several approval numbers if it has been approved as a component of several
replacement exhaust systems.
4.5. The replacement exhaust system shall be supplied in a packaging or carry a label both providing the following
particulars:
(a) The trade name or mark of the manufacturer of the replacement silencing system and its components,
(b) The address of the manufacturer or his representative,
(c) A list of vehicle models for which the replacement silencing system is intended.
4.6. The manufacturer shall provide:
(a) Instructions explaining in detail the correct method of mounting on the vehicle,
(b) Instructions for handling the silencing system,
(c) A list of components with the numbers of the corresponding parts, excluding retainers.
4.7. The approval mark.
5. APPROVAL
5.1. If the NORESS or component thereof submitted for approval under this Regulation meets the requirements of
paragraph 6 below, approval for that type shall be granted.
5.2. An approval number shall be assigned to each NORESS type approved. Its first two digits (at present
01 corresponding to the 01 series of amendments to the Regulation) shall indicate the series of amendments
incorporating the most recent major technical amendments made to the Regulation at the time of issue of the
approval. The same Contracting Party may not assign the same number to another type of NORESS or
component designed for, the same type(s) of vehicle.
5.3. Notice of approval or extension or refusal of approval of a NORESS or component thereof under this
Regulation shall be communicated to the Parties to the Agreement which apply this Regulation, by means of
a form conforming to the model in Annex 1 to this Regulation.16.11.2018 EN Official Journal of the European Union L 290/165
5.4. There shall be affixed to every NORESS and component thereof conforming to a type approved under this
Regulation an international approval mark consisting of:
(a) A circle surrounding the letter ‘E’ followed by the distinguishing number of the country which has granted
approval (1);
(b) The number of this Regulation, followed by the letter ‘R’, a dash and the approval number to the right of
the circle prescribed in (a) above;
(c) The approval number shall be indicated in the approval form, together with the method used for the
approval tests.
5.5. The approval mark shall be easily legible when the NORESS is fitted to the vehicle, and shall be indelible.
5.6. A component may be marked with more than one approval number if it has been approved as a part of more
than one NORESS; in this case the circle need not to be repeated. Annex 2 to this Regulation gives an example
of the approval mark.
6. SPECIFICATIONS
6.1. General specifications
The silencer shall be designed, constructed and capable of being mounted so that:
(a) The vehicle complies with the requirements of this Regulation under normal conditions of use, and in
particular regardless of any vibrations to which it may be subjected;
(b) It displays reasonable resistance to the corrosion phenomena to which it is exposed, with due regard to the
normal conditions of use of the vehicle;
(c) The ground clearance provided by the silencer originally fitted, and the possible inclined position of the
vehicle, are not reduced;
(d) Unduly high temperatures do not exist at the surface;
(e) Its edges are not sharp or jagged and there is sufficient space for shock absorbers and springs;
(f) Adequate clearance of spring parts is provided;
(g) Adequate safety clearance of pipes is provided;
(h) It is tamper-resistant in a way that is compatible with clearly-defined maintenance and installation
requirements;
6.2. Specifications regarding sound levels
The acoustic efficiency of the NORESS or components thereof shall be verified by means of the methods
described in Regulation Nos 9, 41 or 63. In particular, for the application of this paragraph reference shall be
made to the series of amendments to Regulation No 92 which was in force at the time of type approval of the
new vehicle. When the NORESS or its components is fitted to the vehicle described in paragraph 3.3(c), the
sound level values obtained using the two methods (stationary and vehicle in motion) shall satisfy the
following condition:
They shall not exceed the values measured in conformity with the requirements of paragraph 3.3(c), for the
same vehicle when fitted with the original silencing system during the test with the vehicle in motion and the
stationary test.
6.3. Additional requirements
6.3.1. Tampering protection provisions
The NORESS or its components shall be constructed in a way that does not permit removal of baffles, exit-
cones and other parts whose primary function is as part of the silencing/expansion chambers. Where
incorporation of such a part is unavoidable, its method of attachment shall be such that removal is not
facilitated (e.g. with conventional threaded fixings) and shall also be attached such that removal causes
permanent/irrecoverable damage to the assembly.
6.3.2. Multi-mode NORESS
NORESS with multiple, manually or electronically adjustable, rider selectable operating modes shall meet all
requirements in all operating modes. The reported sound levels shall be those resulting from the mode with
the highest sound levels.
(1) The distinguishing numbers of the Contracting Parties to the 1958 Agreement are reproduced in Annex 3 to the
Consolidated Resolution on the Construction of Vehicles (R.E.3), document ECE/TRANS/WP.29/78/Rev. 4 - www.unece.
org/trans/main/wp29/wp29wgs/wp29gen/wp29resolutions.htmlL 290/166 EN Official Journal of the European Union 16.11.2018
6.3.3. Prohibition of defeat devices
The NORESS manufacturer shall not intentionally alter, adjust or introduce any device or procedure solely for
the purpose of fulfilling the sound emission requirements of this Regulation, which will not be operational
during typical on-road operation.
6.3.4. Additional sound emission provisions (ASEP)
The requirements of paragraph 6.3 of the 04 series of amendments to Regulation No 41 shall also be fulfilled
for the NORESS, if it is designed to be used on vehicles that are type approved according to the 04 series of
amendments to Regulation No 41 and are subject to the requirements of paragraph 6.3 of the 04 series of
amendments to Regulation No 41.
If tests are to be performed, the vehicle as described in paragraph 3.3(c) shall be used.
The Type Approval Authority may require any relevant test to verify the compliance of the NORESS to these
requirements.
The manufacturer shall provide a statement in conformity with annex 4 of this Regulation, that the NORESS
or components to be approved comply with the additional sound emission provision requirements of
paragraph 6.3 of the 04 series of amendments to Regulation No 41.
6.4. Measurement of vehicle performance
6.4.1. The NORESS or its components shall be such as to ensure that the vehicle's performance is comparable with
that achieved with the original exhaust silencing system or components thereof.
6.4.2. The NORESS or, at the manufacturer's choice, the components thereof shall be compared with an original
silencing system or components, also in new condition, successively fitted to the vehicle referred to in
paragraph 3.3(c).
6.4.3. The verification shall be carried out by measuring the output curve in accordance with paragraph 6.4.4.1
or 6.4.4.2. The maximum power and the engine speed at maximum power measured with the NORESS shall
not exceed the net power and the engine speed measured under the conditions set out below with the original
equipment exhaust system by more than ± 5 per cent.
6.4.4. Test method
6.4.4.1. Engine test method
The measurements shall be carried out on the engine of the vehicle referred to in paragraph 3.3(c), the engine
being mounted on a dynamometer.
6.4.4.2. Vehicle test method
The measurements shall be carried out on the vehicle referred to in paragraph 3.3(c). The values obtained with
the original silencing system shall be compared with those obtained with the NORESS. The test shall be
conducted on a roller dynamometer.
6.5. Additional provisions regarding the NORESS or its components filled with fibrous materials
The use of fibrous absorbent material shall be permitted in the construction of the NORESS only if the
requirements in Annex 3 are met.
6.6. Evaluation of the emission of pollutants of vehicles equipped with replacement silencer system
The vehicle referred to in paragraph 3.3(c) with the non-original replacement exhaust silencing system
(NORESS) of the type for which approval is requested, shall fulfil the pollution requirements according to the
type approval of the vehicle. The evidence shall be documented in the test report.
7. MODIFICATION AND EXTENSION OF THE APPROVAL OF NORESS AND EXTENSION OF APPROVAL
7.1. Every modification of the type of NORESS or its components shall be notified to the Type Approval Authority
which approved the type of NORESS. The said Authority may then either:
(a) Consider that the modifications made are unlikely to have an appreciable adverse effect, or16.11.2018 EN Official Journal of the European Union L 290/167
(b) Require a further test report from the Technical Service responsible for conducting the tests.
7.2. The manufacturer of the NORESS or component thereof or his duly accredited representative may ask the Type
Approval Authority which has granted the approval of the NORESS for one or several types of vehicle for an
extension of the approval to other types of vehicle. The procedure shall be as described in paragraph 3 above.
7.3. Confirmation or refusal of approval, specifying the modifications, shall be communicated in accordance with
the procedure specified in paragraph 5.3 above to the Contracting Parties to the Agreement applying this
Regulation.
7.4. The competent authority issuing the extension of approval shall assign a series number to each communication
form drawn up for such an extension.
8. CONFORMITY OF PRODUCTION
The conformity of production procedures shall comply with those set out in the Agreement, Appendix 2
(E/ECE/324-E/ECE/TRANS/505/Rev.2), with the following requirements:
(a) The NORESS approved to this Regulation shall be so manufactured as to conform to the type approved by
meeting the requirements set out in paragraph 6 above.
(b) The holder of the approval shall ensure that for each type of NORESS at least the tests prescribed in
paragraph 6 of this Regulation are carried out.
(c) The authority which has granted type approval may at any time verify the conformity control methods
applied in each production facility. The normal frequency of these verifications shall be once every two
years.
(d) The production is considered to conform to the requirements of this Regulation, if the provisions of
Regulations Nos 9, 41 and 63, corresponding to the type of vehicle, are complied with and if the sound
level measured by the method described in the given Regulations during the test in motion does not exceed
by more than 3 dB(A) the sound level measured during the type approval and does not exceed by more
than 1 dB(A) the limits prescribed in Regulations Nos 9, 41 and 63 as applicable.
9. PENALTIES FOR NON-CONFORMITY OF PRODUCTION
9.1. The approval granted in respect of a type of NORESS or its components under this Regulation may be
withdrawn if the requirements laid down in paragraph 8 above are not complied with, or if the NORESS or its
components fail to pass the tests provided for in paragraph 8(b) above.
9.2. If a Contracting Party to the Agreement applying this Regulation withdraws an approval it has previously
granted, it shall forthwith so notify the other Contracting Parties to the 1958 Agreement applying this
Regulation, by means of a communication form conforming to the model contained in Annex 1 to this
Regulation.
10. PRODUCTION DEFINITIVELY DISCONTINUED
If the holder of the approval completely ceases to manufacture a type of replacement silencing system or
components thereof in accordance with this Regulation, he shall so inform the authority which granted the
approval which shall in turn inform thereof the other Contracting Parties to the 1958 Agreement applying this
Regulation, by means of a copy of the communication form conforming to the model contained in Annex 1 to
this Regulation.
11. NAMES AND ADDRESSES OF TECHNICAL SERVICES RESPONSIBLE FOR CONDUCTING APPROVAL TESTS, AND OF
TYPE APPROVAL AUTHORITIES
The Contracting Parties to the 1958 Agreement which apply this Regulation shall communicate to the United
Nations Secretariat the names and addresses of the Technical Services responsible for conducting approval tests
and of the Type Approval Authorities which grant approval and to which forms certifying approval or
extension or refusal or withdrawal of approval, or production definitively discontinued issued in other
countries, are to be sent.L 290/168 EN Official Journal of the European Union 16.11.2018
ANNEX 1
PART A
FOR NORESS FOR VEHICLE TYPES APPROVED ACCORDING TO THE 04 SERIES OF AMENDMENTS TO
REGULATION No 4116.11.2018 EN Official Journal of the European Union L 290/169L 290/170 EN Official Journal of the European Union 16.11.201816.11.2018 EN Official Journal of the European Union L 290/171
PART B
FOR NORESS FOR VEHICLE TYPES APPROVED ACCORDING TO REGULATION No 9 OR REGULATION
No 63L 290/172 EN Official Journal of the European Union 16.11.201816.11.2018 EN Official Journal of the European Union L 290/173L 290/174 EN Official Journal of the European Union 16.11.2018
ANNEX 2
EXAMPLE OF THE APPROVAL MARKS
(See paragraph 5.4 of this Regulation)
a = 8 mm min
The above approval mark affixed to a component of silencing systems shows that the replacement silencing system type
concerned has been approved in the Netherlands (E 4) pursuant to Regulation No 92 under approval No 012439. The
first two digits of the approval number 01 indicate that the approval was granted in accordance with the requirements
of this current Regulation No 92 whilst the approval number 00 indicate that the approval was granted in accordance
with the requirements of Regulation No 92 in its original form.16.11.2018 EN Official Journal of the European Union L 290/175
ANNEX 3
REQUIREMENTS FOR FIBROUS ABSORBENT MATERIALS USED IN NORESS
(See paragraph 6.5 of this Regulation)
1. Fibrous absorbent material shall be asbestos-free and may be used in the construction of silencers only if suitable
devices ensure that the fibrous absorbent material is kept in place for the whole time that the silencer is being used
and it meets the requirements of any one of sections 2, 3, 4 or 5 according to the manufacturer's choice.
2. After removal of the fibrous material, the sound level shall comply with the requirements of paragraph 6.2 of this
Regulation.
3. The fibrous absorbent material may not be placed in those parts of the silencer through which the exhaust gases pass
and shall comply with the following requirements:
(a) The material shall be heated at a temperature of 650 ± 5 °C for four hours in a furnace without reduction in
average length, diameter or bulk density of the fibre.
(b) After heating at 650 ± 5 °C for one hour in a furnace, at least 98 per cent of the material shall be retained in
a sieve of nominal aperture size 250 µm complying with ISO 3310/1 when tested in accordance with ISO 2599.
(c) The loss in weight of the material shall not exceed 10,5 per cent after soaking for 24 hours at 90 ± 5 °C in
a synthetic condensate of the following composition:
(i) 1 N hydrobromic acid (HBr), 10 ml
(ii) 1 N sulphuric acid (H SO ), 10 ml
2 4
(iii) Distilled water to make up to 1 000 ml
Note: The material shall be washed in distilled water and dried for one hour at 105 °C before weighing.
4. Before the system is tested in accordance with paragraph 6.2 of this Regulation it shall be put into a normal state for
road use by one of the conditioning methods in accordance with and as described in paragraph 5.1.4 of Annex 3 of
Regulation Nos 9 or 63 or in paragraph 1.3 of Annex 5 of Regulation No 41, whatever is applicable.
5. Exhaust gases are not in contact with fibrous materials and fibrous materials are not under the influence of pressure
variations.L 290/176 EN Official Journal of the European Union 16.11.2018
ANNEX 4
STATEMENT OF COMPLIANCE WITH THE ADDITIONAL SOUND EMISSION PROVISIONS