Transmitter signals precise air velocity adjustments to computer-controlled variable-speed fan motor. Either of two methods used to measure air velocity. Air velocity transmitter controls drying oven air flow. Determine air velocity and temperature levels in ducts or air supply grills. Eliminate the need for Pitot tubes, orifice plates, differential pressure sensors and temperature sensors with a Series VTT. Handheld anemometer enables measuring duct flow measurements. Measuring velocity or volume of air flow in duct. Air flow switch protects preheater from overheating.