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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”
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.
When using a mechanical flow sensor, such as a pitot tube, differential pressure can also be used to determine flow velocity and volumetric flow. Continue reading “Velocity Measurement and Environmental Effects”
Calibration is the comparison and adjustment of a reading from an instrument
in correlation with the reading of a higher accuracy piece of equipment. The overall goal of this process is to minimize measurement uncertainty and ensure the accuracy of an instrument.
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”