Today I am reviewing some of the common Pitot Tubes by Dwyer. Pitot tubes are commonly used to monitor air velocity and flow rate in residential, industrial, and commercial HVAC. Pitot tubes (with the help of a differential pressure instrument) calculate air velocity and flow rate by first measuring static pressure and dynamic pressure. If there is an increase in dynamic pressure and a decrease in static pressure, there is an increase in flow rate/velocity. If you picture a car driving and colliding into air, the front of the car would have dynamic pressure, and the back of the car would have static pressure. The same thing is happening to a pitot tube when you insert it into a duct or pipe. By comparing dynamic pressure (changing) vs. static pressure (constant/unchanging) you can determine there is a flow, and how fast that flow is occurring.

Pitot tubes by themselves cannot perform any measurements. They must be connected to some sort of differential pressure instrument such as a manometer. The pressure that the pitot tube is experiencing in its environment (a duct for instance) is carried through into the manometer for it to calculate.

The Dwyer 160 series pitot tubes are designed so that the static pressure port is parallel to the sensing tube in order to make it easier for the user to align the tube with the airflow. The Dwyer 160 series pitot tubes are made out of a durable stainless steel and have permanently etched insertion depth graduations. The Dwyer 160F series pitot tubes are exactly the same as the 160 series, but are straight instead. This design is better for directly measuring the airflow through a grill or pressure tap. These pitot tubes come in many different sizes depending on how big the ducts are. For those that truly have many areas to measure using pitot tubes, there is the 160-KIT and 160F-KIT. These kits include all of the pitot tubes of that style with lengths including 18”, 24”, 36”, and 48”.

Did you know that even airplanes use pitot tubes on their wings to determine speed?