General Guidelines - IMS 3638 Manual Del Usario

6) Vehicle conditions:
a) In what physical conditions must the vehicle be?
b) Should the vehicle be in a specific position during testing (especially relevant for
motorbikes)?
7) Measurement method:
a) How must the throttle/engine be operated during testing?
b) How many measurements must be taken during a test?
c) How long should the engine speed be held constant?
d) How long should a single measurement last?
e) What sound levels must be measured?
f) What type of sound level meter must be used for measuring?
g) Are there other types of outputs that must be measured (for example: compressed
air noise)? If so, are there specific methods of measuring these outputs?
h) If multiple measurements are taken, which result should be reported?
i) What other information should be included in a test report?
j) Are there any exceptions or special conditions?

General Guidelines

Test procedures must always follow those requirements set forth by current law(s) or stand-
ard(s). If no procedures are specified, the general rule is as follows (based on the 70/157/EEC
standard):
The microphone should be level with the exhaust system outlet, 0.5 m (1.64 ft) away at a
°
45 angle. The vehicles RPM test value should be for 4-wheel vehicles at 3/4 of the en-
gine's maximum net power (see the relevant manufacturer's specifications); a 2-wheel
should be at 1/2 of the engine's maximum net power.
The area, in which the vehicle is being tested should be a flat, open surface, free of extra
persons, billboards, trees, walls, tall grass and any other matter that can reflect sound. Any
background noise should be at least 10 dB under the sound produced by the exhaust system.
Rainy and windy conditions should be avoided.
The vehicle must be tested at normal operating temperature with the gear lever in neutral
position.
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