Document ID: chunk:federal_register_of_legislation:F2021C00509:reg:6:p12
Version: federal_register_of_legislation:F2021C00509
Segment Type: reg
Provision Reference: reg 6 (pt 12/15)
Character Range: 190265–193261

example, placing the moped on its stand.

          3.2.3.3.                             Measuring of noise in proximity to the exhaust (see appendix, fig.2)

          3.2.3.3.1.                       Position of the microphone

          3.2.3.3.1.1.                The height of the microphone above the ground must be equal to that of the outlet pipe pf the exhaust gases, but in any event shall be limited to a minimum value of 0.2 m.

          3.2.3.3.1.2.                The microphone must be pointed towards the orifice of gas flow and located at a distance of 0.5 m from the orifice.

          3.2.3.3.1.3.                Its axis of maximum sensitivity must be parallel to the ground and must make an angle of 45 degrees +/- 10 degrees with the vertical plane containing the direction of the gas flow. The instructions of the manufacturer of the sound level meter with regard to this axis must be respected. In relation to this plane, the microphone shall be placed in such a way as to obtain the maximum distance from the longitudinal median plane of the moped; in case of doubt, the position which gives the maximum distance from the contour of the moped shall be selected.

          3.2.3.3.1.4.                In the case of an exhaust provided with two or more outlets spaced less than 0.3 m apart, only one measurement is made; the microphone position is related to the outlet nearest to the external side of the moped or, when such outlet does not exist, to the outlet which is the highest above the ground.

          3.2.3.3.1.5.                For moped having an exhaust provided with outlet spaced more than 0.3 m apart, one measurement is made for each outlet as if it were the only one, and the highest level is noted.

          3.2.3.3.2.                       Operating conditions of the engine

          3.2.3.3.2.1.                Engine speed shall be held steady at one of the following values :
          1/2 S, if S exceeds 5,000 rpm,

          3/4 S, if S does not exceed 5,000 rpm,
          where S is the engine speed at which the engine produces its maximum power.

          3.2.3.3.2.2.                When the constant engine speed is reached, the throttle shall be returned swiftly to the idle position. The sound level shall be measured during a period of operation consisting of a brief maintenance of the constant engine speed and throughout the deceleration period.

          3.2.3.3.3.                       The values rounded off to the nearest whole decibel, shall be read from the measuring apparatus. If the figure following the decimal point is between 0 and 4, the total is rounded down and if between 5 and 9, it 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