The Air Monitor multi-point self-averaging pitot averaging technology is unique in that it is a pure instrument measuring true velocity pressure (total pressure – true static pressure). Other technologies measure a reference pressure on the back or side of the probe resulting in a DP that is not true velocity pressure as derived from Bernoulli’s Equation. This reference pressure requires the use of correction factors that vary with Reynolds number (i.e. velocity and density changes) in order to relate the measured DP to true velocity pressure. The Air Monitor system also utilizes the Fechheimer method of true static pressure measurement along with a chamfered impact or total pressure measurement to provide an accurate velocity pressure measurement and do so with pitch and yaw angles up to ± 30 degrees without requiring additional corrections.
Differential Pressure technology is commonly used to measure fluid velocity due to their well-defined relationship. The square root of the differential pressure is proportional to the velocity of the fluid. In ducted systems the total pressure consists of the velocity pressure and static pressure. By measuring the total and static pressures in a duct, the velocity pressure can be obtained by subtracting static pressure from total pressure. This is achieved in practice by directly measuring the differential pressure between the two. Airflow measurement over a large velocity range requires an extensive selection of DP transducers with multiple upper range limits (URLs) to fit the required application – from ultra-low range like 0.05” w.c. URL transducer and higher. Air monitor offers this ultra-low range DP sensing capability coupled with the Auto-zero function to provide a highly accurate DP measurement with long term calibration stability starting for 0.05” w.c. URL transmitters.