High precision measurement of dust content in gas

In order to measure aerosol in gas of electronic and accurate manufacturing industry, a new method on measuring dust content with high precision by using superfine and high purity fiberglass is presented. As Fiberglass has the advantage of small diameter and high porosity, dust in gas will be intercepted completely by the fiberglass when the gas flows through the sampling tube filled with fiberglass. Dust content in gas can be calculated on condition that volume of gas flowing through the sampling pipe at unit time is measured. Collected efficiency increases with fiberglass filling thickness, filling ratio and single fiber collected efficiency while decreases with fiber diameter. Collected efficiency should be more than 99.5% if diameter of fiberglass is selected at 3 mum. The best temperature for baking fiberglass tube is 110degC. The best baking time is 6 h and cooling time to constant weight must be more than 4 h. Purity of the fiberglass has great influence on its stability. For the fiberglass with a purity of 99.5%, Weight loss is less than 0.1 mg for six hours in the oven. It can be seen from the comparison experiment of fiberglass filtering method, sampling gravimetric method and optical scattering method. The fiberglass filtering method is not affected by ambient and gas temperature. The error of fiberglass filtering method is about 0.1% of the sampling gravimetric method and 1% of the optical scattering method.