Particulate matter sampler

A particulate matter sampler is an instrument for measuring the properties (such as mass concentration or chemical composition) of particulates in the ambient air.

Two different types of particulate matter samplers exist that measure particulate mass concentration: manual samplers and automated samplers..

Manual samplers draw a known volume of air through a filter. The filter is weighed on an analytical balance before and after sampling, and the difference in weight divided by the volume of air pulled through the filter gives the mass concentration of the particulate.

Automated samplers do the weighing in the field. There are two types of automated samplers in common usage: samplers that use a beta gauge for mass measurement and samplers that use a tapered element oscillating microbalance (TEOM) for mass measurement.

Beta gauge particulate samplers have an appearance that is similar to a reel to reel tape recorder. Air is pulled through a filter tape to accumulate a sample, the mass of the tape before and after sampling is determined by advancing the tape spot into the beta attenuation cell.

The tapered element oscillating microbalance (TEOM) particulate sampler operates by drawing air through a filter attached at the tip of a glass tube. An electrical circuit places the tube into oscillation, and the resonant frequency of the tube is proportional to the square root of the mass on the filter.

Recently, microphone based instruments have been devised that monitor noise levels in specific frequency bands to predict local PNC levels. Prototypes of such instruments have been tested in Europe and in Bangalore.

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