An apparatus consisting of a small, polished, stainless steel / nickel plated cup placed in a container into which is passed the sample gas. The temperature of the polished surface is lowered by immersing dry ice (solid carbon dioxide) in an acetone solution contained in the cup. The temperature at which fog appears on the cup is the dew point of the sample.
Dew point apparatus:
This is an assembly of special alloy metallic tube which is fixed in a metallic block & transparent bowl. Block is having inlet connection of compressed air/gas whose dryness must be measured. A glass Thermometer is used to measure the temp. inside the metallic tube, or a digital indicator is used to measure the temp outside the metallic tube surface (in digital model). Supplied with Glass Thermometer ( -100°C to +50°C x 1°C).
Compressed air/gas is connected to the apparatus and is circulated inside the bowl around the tube at atmospheric pressure and vented to the atmosphere. The mixture of dry ice (CO2 ice) and acetone/ether lowers down the temp. of the tube, the temp. is measured with the help of glass thermometer / Digital temp. indicator. When the brightness of the tube becomes dull due to mist formulation on the tube, temp. is noted down. The temp. is the dew point and corresponding to this, the moisture content of the air can be seen from the table indicated ppm, thus determining its dryness. Max.80 ppm moisture content air is recommended for instrumentation and the corresponding dew point is (40° C).
