Optical tachometer
Commissioning Air Systems (BG 49/2015), written by Chris Parsloe and published by BSRIA in March 2015, explains how to commission ducted air distribution systems in buildings. It was originally published in 2013 and was then updated in 2015.
It states: ‘Optical tachometers should be used to measure fan and pump rotational speeds in preference to mechanical tachometers since their use does not involve contact with moving machine parts. This instrument projects a narrow beam of light toward the rotating shaft or pulley on which has been fixed a strip of reflecting tape. The reflected light pulses from the tape are measured as frequency (rev/min) by the meter. To be effective, the meter should be held in close proximity to the shaft or pulley.’
See also:
--BSRIA
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