The report explains the maintenance, calibration, and operation of the isokinetic air pollution source-sampling equipment. This procedure has been used satisfactorily and is presented as a guide to assist interested personnel in using the equipment. The sampling train has four major components: The pitobe assembly, which includes the probel nozzle, a heated glass probe, and a pitot tube for monitoring gas velocity during sampling; The meter box assembly, which consists of a system of manometers, an orifice meter, a vacuum pump, a dry gas meter, and electrical controls for sampling; The sample box assembly, which contains the glassware; and The umbilical cord, which connects the sample box with the meter box. The maintenance and calibration procedure described for each of the components should be followed in the shop or laboratory in preparation for each sampling test. (Author)