HOW THE DUSTTRAK WORK
The dusttrak is very easy to work with. It has a pipe that sucks air into it has a filter to keep particles which are too big but lets small particles in. PM2.5 are very bad for your health. The way we have it set up is to measure PM 2.5 (particles less than 2.5 µm in diameter) It’s a very important machine to help get data about how much PM2.5 there is in the air. Before we went sampling we have to make sure that it works. We check it every 30 minutes while we are sampling.
HOW THE WCPC WORK
The
WCPC measure the number of PM0.1. The
WCPC takes an air sample and counts the number of particles in that sample.
This count divided by the flow rate shows on the front of the display.
The
WCPC uses a laser and optical detector to count the particles by passing the
air sample through through a laser. The instrument uses water to grow the
particles so they can be detected by the laser system.
This instrument uses water as working fluid because
it is safe and clean. The aerosol sample
flows through the path from the sample inlet to the optical detector. The
WCPC draws in 0.60 L/min total flow but 0.48 L/min is minimizing particle
loss at the inlet. The rest 0.12 L/min aerosol flows immediately into the
process media. The aerosol stream is saturated with water vapor and is temperature
equilibrated. Then the sample passes growth section and heated the wall and
produce vapor pressure. Particles in the flow stream act as nuclei for condensation.
Water continues to condense on the particles as it passes up the growth tube and the enlarged
particles are then detected by the optical detector.
