Differential pressure measurement can be beneficial in a wide variety of building automation system (BAS) applications.
One of these applications involves determining if a filter in your system needs to be cleaned or replaced. Filter health can be established by monitoring the pressure on the primary and secondary sides of a filter. A clean filter will typically have a baseline differential pressure generated as air flows through it. As the filter becomes dirty, this differential pressure increases.
If you’ve ever spent time in a hospital, you may have noticed a device similar to a home thermostat mounted on the wall with a display stating “ACH”. What exactly does “ACH” stand for and why is it important in a building or hospital? Continue reading “What is ACH and Why is It Important?”
Pitot tubes are based on Bernoulli’s equation, which states that 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”
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”