Boost Venturi Probes are used to amplify the measured velocity pressure in a flowing fluid. The measured total pressure is unchanged from a Pitot-Static reading but the flow is accelerated in the venturi passages, as in a flow nozzle, so the static pressure reading is lower than that obtained with a Pitot-Static probe.
The magnitude of the boost or gain is defined as: (PT2 - PS2)/(PT1-PS1) where PT2, PS2 are total and static pressures measured by the probe and PT1, PS1 are free stream values as measured by a conventional Pitot-Static probe. The standard Boost Venturi probes (Types A and B) provide approximate gain figures of 10 and 4.
By amplifying the velocity pressure difference (PT - PS) with a Boost Venturi, a more accurate measurement can be made of this difference. This increase in accuracy will be achieved, however, only if the probe's gain is accurately known, and this may require that the probe be calibrated under actual flow conditions.
When used for monitoring a fixed flow, a Boost Venturi gives a lower permanent pressure drop than an orifice. These probes may also be used with a differential pressure controller to perform flow control and / or limit functions.
Large outer venturi encompassing smaller inside venturi for maximum gain of 9 plus. [view dimensions]
Smaller more compact venturi for maximum gain of 3 plus. [view dimensions]