EPA \ TAQMN \ Air Quality Monitoring \ Instrument database \ Suspended particles(PM10)-beta-ray analysis

Suspended particles(PM10)-beta-ray analysis

Beta ray analyzer can effectively analyze the concentration of particles within the air. It can automatically and continuously monitor particles in the air for long time. The design principle of the instrument is based on the differences of radiation strength on the filter paper, and then the system would measure the concentration of the particles. The sample gas of the atmosphere is imported into the system through an air pump. Before entering the analysis system, it will pass through the sampling system, which includes sampling location, sifter, and heater. Its purpose is to determine the diameter of particles such as PM10 or PM2.5 that can enter the analysis system and eliminating the interference of water.

When the sample gas enters the system, it will pass through the filter paper made of special material that can gather and adsorb the particles in the air. The system contains radioactive components (like C14 element as the radioactive substance) to emit radioactive pulse. After the radiation goes through the filter paper, it will be received by a counter used to count the strength of pulse.

Before the filter paper gathers particles, the radiation strength of empty filter paper will be measured, so the difference before and after the filter paper gathers particles can be known. The difference of strengths is proportional to the mass of particles; therefore, the system can count the concentration of particles in the air (PM10 or PM2.5) accordingly.

Instruments measured the concentration of PM10 of the process (beta-ray analysis)

last update : 2017/07/31