Understanding Air Velocity Sensors

Stainless Steel Pitot Tube, Series 160

Dwyer Instruments, Inc. offers a multitude of sensors for monitoring air velocity in HVAC systems. Some of this instrumentation has a simple construction (Pitot tubes, for example) while others are more complex, such as hot-wire anemometers.

The initial term and first “hot-wire anemometer” was developed back in 1914 by Louie Vesso King. He is also accredited for King’s Law, which mathematically describes heat transfer in air flows using a heated wire. As the air moves over the wire, it causes a loss of temperature in the wire and removes some of the wire’s heat energy. Continue reading “Understanding Air Velocity Sensors”

Air Velocity and Flow Measurement with Pitot Tubes

Dwyer Instruments offers many styles of Pitot tubes, which are a commonly used sensor  for monitoring air velocity and flow rate in heating, ventilation, and air conditioning.

Pitot tubes are based on Bernoulli’s equation, which states an increase in the speed of a fluid occurs simultaneously with an increase in dynamic pressure and a decrease in static pressure.  Pitot Tubes sense the dynamic pressure of the fluid flow at a particular point and were invented by French Engineer Henri Pitot in the early 18th century.

Continue reading “Air Velocity and Flow Measurement with Pitot Tubes”