Document ID: chunk:federal_register_of_legislation:F2021C00509:reg:6:p13
Version: federal_register_of_legislation:F2021C00509
Segment Type: reg
Provision Reference: reg 6 (pt 13/15)
Character Range: 192939–196049

is rounded up.
          Only values which are obtained from three consecutive measurements which do not differ by more than 2 dB(A) shall be accepted.
          The highest of the three measurements will constitute the test result.

          4.                                               INTERPRETATION OF RESULTS FOR VEHICLES IN MOTION

          The values taken shall be rounded off to the nearest whole decibel. If the figure following the decimal point is between 0 and 4, the total is rounded down and if between 5 an 9, it is rounded up.
          Only the values of readings obtained from two consecutive measurements made on the same side of the vehicle and not differing by more than 2 dB(A) shall be accepted.
          To allow for lack of precision in the readings, the result of each measurement shall be taken as equal to the value obtained, less l dB(A) .
          If the average of the four readings does not exceed the maximum permissible level for the category to which the tested vehicle belongs, the limit specified in paragraph 6.2.1.3. shall be deemed as being complied with. This average value shall constitute the test result.

          5.                                               ORIGINAL EXHAUST (SILENCING) SYSTEM

          5.1.                                         Requirements for silencers containing absorbent fibrous materials.

          5.1.1.                                   Fibrous absorbent material must 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 5.1.2., 5.1.3. or 5.1.4.

          5.1.2.                                   After removal of the fibrous material, the sound level must conform to the requirements of annex 4.

          5.1.3.                                   The fibrous absorbent material may not be placed in those parts of silencer through which the exhaust gases pass and must conform to the following requirements:

          5.1.3.1.                             The material shall be heated at a temperature of 650 +/- 5 degrees C for four hours in a furnace without reduction in the average length, diameter or bulk density of the fibre ;

          5.1.3.2.                             After heating at 650 +/- 5 degrees C for one hour in a furnace, at least 98% of the material must be retained in a sieve of nominal aperture size 250 micrometers conforming to ISO standard 3310/1 when tested in accordance with ISO standard 2599 ;

          5.1.3.3.                             The loss in weight of the material must not exceed 10.5% after soaking for 24 hours at 90 +/- 5 degrees C in a synthetic condensate of the following composition :
          1 N hydrobromic acid (HBr) 10 ml
          1 N sulphuric acid (H2SO4) 10ml
          Distilled water to make up to l,000 ml

          Note: The material must be washed in distilled water and dried for one hour at 105 degrees C before weighing.

          5.1.4.