Sun to supply VI smoke meters
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• Diagnostic and service equipment manufacturer Sun is to supply the Vehicle Inspectorate (VI) test stations with smoke meters. Sun will make the meters which were jointly developed with GEC which makes the sensor and has been awarded the VI contract.
The meter's measuring optic is in the sensor head which clamps directly onto the exhaust. A hand controller is connected via a cable.
the meter self tests before the sensor head is clamped onto the exhaust and after the test is completed. The examiner sits in the driving seat during the test while the computerised unit tells him what to do throughout.
The pass/fail figure has been set at 3.2m—' for both turbocharged and naturally-aspirated engines but there is a pause of several seconds between each acceleration to allow the turbo to slow down. This limit is said to be identical to that of the subjective test it replaces.
If four consecutive accelerations average out to below that figure the unit will automatically stop the test. If not, up to ten tests will be carried out before lair is dis played. At the end of the test the unit is plugged into a printer to give a hard copy.
By allowing the turbocharger to slow down or stop between each acceleration the smoke level may be higher for the next acceleration. During one trial 80% of the turbocharged vehicles in a truck fleet failed the test against an average of 30% overall.
There is proposed European legislation that sets the limit at a Om—' for turbocharged engines and 2.5m-1 for naturally aspirated.
Although the order has been placed the VI does not yet have an approval system and standard for smoke meters. This should be ready soon and a list of approved meters will be published by the Garage Equipment Association.