Optical Smoke Meter: Method of Operation
The meter measures smoke density by passing a sample of the engine exhaust gases through a light path and measuring the attenuation of the light at a photo-detector. See gas path schematic below.
To prevent condensation and loss of particulates, the gas sample is routed into the meter via a connector on the rear panel of the instrument and passes through a coil, where it is heated by hot air from a heater block built into the instrument.
The entire sample module is heated to a temperature of 55°C to ensure a stable environment with minimum risk of condensation from the sample.
Diagram shows: Optical Smoke Meter Gas Path Schematic.
If necessary, the gas sample can be filtered to remove particulates before sampling. This is achieved by closing the motorised valve MV1 and opening valve SV1. The sample is then drawn to the Smoke Cell through filter F1.
Opening and closing of solenoid and motorised valves is normally performed by the meter control electronics to ensure satisfactory operation, but can be controlled manually if required. Full details of the meter operation are given in our Optical Smoke Meter User’s Guide, a copy of which is available free of charge on application to Rotadata Limited, Derby Sales Department.
