ABSTRACT
There are three broad categories of air and gas measuring devices: those that measure volume directly, those that measure rate of gas flow, and those that measure velocity of gas. This chapter considers the direct volume instruments. It reviews the design of the following gas volume meters, together with a discussion of calibration techniques and applications to air sampling: spirometer, displacement bottle, soap-bubble meter, mercury-sealed piston, roots meter, wet test meter (WTM), and dry gas meter (DGM). A DGM can be calibrated against a spirometer, WTM, or displacement bottle. One big advantage of the DGM over a WTM is that no correction for water vapor is needed. DGMs are used extensively in air sampling field work, particularly in emission sampling. The primary application of roots meters in air sampling has been as a flow calibration standard for total suspended particulate samplers and other high-flow sampling devices.
