Sch 9Method for determining the concentration of carbon monoxide and hydrocarbons in the exhaust gases of a motor vehicle

Schedule 9—Method for determining the concentration of carbon monoxide and hydrocarbons in the exhaust gases of a motor vehicle

Regulations 137 and 138

Part A—Idle test

1. An idle test of a motor vehicle must be conducted in the following manner, using the equipment set out in Part C—

(a) the engine of the vehicle must be running and be at normal operating temperature; and

(b) the inlet end of a sampling probe must be positioned in the exhaust pipe of the vehicle at any point between 35 centimetres and 50 centimetres from the discharge end of the exhaust pipe; and

(c) the accelerator pedal of the vehicle must not be depressed; and

(d) if the vehicle is equipped with a manual transmission, the transmission must be kept in neutral gear with the clutch engaged; and

(e) if the vehicle is equipped with automatic or semi-automatic transmission, the transmission must be kept with the gear selector engaged in the drive position with the vehicle's handbrake in the fully on position; and

(f) if the vehicle is equipped with a manual choke, the choke must be off.

2. The measurement must be taken by noting the maximum value of the concentration of carbon monoxide [in % vol] and total hydrocarbons [in ppm] as determined by the analyser over a period of between 30 seconds and 60 seconds beginning not earlier than 60 seconds after the probe has been inserted in the exhaust pipe.

3. If the motor vehicle is equipped with more than one exhaust pipe, the concentration must be measured in each exhaust pipe and the maximum value is taken to be the average value from all pipes.

4. If required for the purposes of testing, the exhaust pipe may be temporarily extended by an extension piece connected to the designed discharge outlet by means of a suitable connection which does not allow dilution of the exhaust gases by air.

Part B—High idle test

5. A high idle test of a motor vehicle must be conducted in the following manner, using the equipment set out in Part C—

(a) the engine of the vehicle must be running and be at normal operating temperature; and

(b) the inlet end of a sampling probe must be positioned in the exhaust pipe of the vehicle at any point between 35 centimetres and 50 centimetres from the discharge end of the exhaust pipe; and

(c) the accelerator pedal of the vehicle must be depressed and the engine rotational speed must be stabilised within the range of 2500 rpm to 3000 rpm; and

(d) if the vehicle is equipped with a manual transmission, the transmission must be kept in neutral gear with the clutch engaged; and