Andersen's Beta Gauge does not require a user's radiation license. The Andersen FH621-N Beta Gauge Sampler is designed to continuously measure the mass concentration of PM 10 particles in ambient air. The sampler also does not heat the measurement chamber which, if heated, can drive oft volatile particles and cause errors in measurements. The central instrument includes filter strip mechanism, radiation measuring chambers, LCD display with control keys, and the complete electronic circuitry. The parallel plate inlet, insect screen, and conical flow deflector yield accurate sampling independent of wind speed and precipitation.
Air is drawn into the inlet and deflected downwards into the acceleration jet of the impactor unit.
By virtue of their greater momentum, particles larger than the 10 micron cut-point impact out and are retained in the middle plenum impaction chamber. The particle fraction smaller than 10 microns is carried vertically upward by the air flow and down the vent tubes to the beta gauge sampler. Principle of Beta Attenuation Ambient air is pulled through the PM 10 sample inlet and dust particles are deposited on the glass fiber filter tape. A low level of beta radiation is emitted from the source which passes through the filter tape and deposited dust. The increase of particles collected on the tape causes a lower beta-ray measurement in the measuring chamber.