High Volume Air Samplers
High Volume Samplers are the basic instruments used to monitor Ambient Air Quality. They are in widespread use all over the world to measure air pollution in industrial areas, urban areas, on the shop floor, near monuments and other sensitive areas. The High Volume Sampler is a vital tool for studies relating to impact of industrialisation to the air analysis, and for work related diseases of the respiratory system to air pollution. These are very much essential for various Environmental Impact Assessment studies.
PRINCIPLE OF OPERATION
In these samplers, air-borne suspended particulates (SPM) are measured by passing air at a high flow-rate of 1.1 to 1.7 cubic meters per minute through a high efficiency filter paper which retains the particles. The instrument measures the volume of air sampled, while the amount of particulates collected is determined by measuring the change in weight of the filter paper as a consequence of the sampling. The passage for air reaching the filter is designed to prevent heavier settleable dust particles from reaching the filter thus measuring the concentration of Suspended Particulate Matter (SPM) in atmospheric air.
In high volume sampler provisions have been made for simultaneous sampling of gaseous pollutants. Here the air is passed through suitable reagents that would absorb specific gases where gaseous pollutants like SO2, NOx, Cl2, H2S, CS2, NH3, etc. are analysed subsequently by simple wet chemistry method to determine the concentration of specific pollutant.