New Meter Measures Exhaust Smoke
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r-I A NEW device, known as the Smoke
meter, designed to measure the smoke density of oil-engine exhaust gases, has been developed by Leslie Hartridge, Ltd., Buckingham, at the research station of British Petroleum Co., Ltd. The meter has been used for many thousands-of hours both on test beds and in vehicles, on the road with highly satisfactory results.
It consists of a light source and a photo-electric -cell mounted at each end of a swinging arm. There are two tubes 1 ft. 6 .in, long, one of which contains clean air supplied under a slight pressure by an electric blower, and the other Which contains a continuous sample of the exhaust gas, led from the vehicle exhaust manifold or tailpipe.
The light source and photocell can be moved together so that the path of light to the cell passes either through the tube containing the exhaust saniple, or through the tube containing clean air. The output from the photocell is connected to a microammeter which is calibrated to indicate smoke density. The air tubeis dimensionally identical with the smoke tube and acts as a datum for use during testing.
Condensation troubles in the smoke tube, which have been a source -of error in other meters, are avoided, as with the dual-tube principle the smoke tube can be kept at a temperature higher than the exhaust dew point. Deposition of carbon on the bulb and the photocell glass is avoided by a protective screen of clean air which passes over them. .
The object of the development of this instrument is to 'create a standard of smoke content in exhaust gases of oil engines, thereby enabling operators to check and control the smoke density of the exhaust.
The meter will be exhibited at the Geneva Show next month, together with other Hartridge products.