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The velocity of an air stream in a duct is not uniform over the cross section of the duct. This is because friction against duct walls causes the air velocity to be lower near the sides than the velocity in the center, creating a parabolic velocity profile. Continue reading “Duct Traversing for Average Air Velocity and Air Volume”
The cleaning of produced water during oil and gas production and exploration is a crucial, although costly endeavor. In the process of bringing oil and gas up to the surface from a well, several byproducts are also produced. Water is the largest of these byproducts by volume, with 882 billion gallons produced per day. This produced water contains a variety of other compounds and substances, including organic and inorganic compounds, grease, bacteria, and dissolved solids such as iron. Continue reading “The Intricacy of Proper Instrumentation in Cleaning Produced Water”
Dwyer Instruments 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 “The Basics of Air Velocity Sensors”
Have you ever wondered why there are a multitude of sensor output signals that can be configured on pressure, temperature, humidity, or gas sensing instrumentation used in process or HVAC applications? Most of these offerings were originally set up to allow sensor manufacturers to better align with the inputs offered by manufacturers of programmable logic controllers (PLCs) and direct digital controllers (DDCs), which are used for controlling processes for both automation and HVAC control.
I’d like to focus on two of the most commonly used output signals and zero in on the advantages and/ or disadvantages these output signals offer. Two of the most commonly used output signals include analog current, typically 4 to 20mA, and analog voltage, typically 0-10V. Continue reading “Understanding Sensor Output Signals”
Question: Is there a kit I can buy with the Magnehelic® Differential Pressure Gage for monitoring air filters, so that I don’t have to buy all the tubing, static pressure tips, and a bracket separately?
Continue reading “Ask the Expert – Monitoring Air Filters with the Magnehelic® Gage”