Averaging Pitot Tube
Averaging pitot tube (Annubar) , such as orifice plate, flow nozzle or venturi tubes are classified as measuring devices which utilize differential pressure to measure flow rate. The measuring principle utilize the difference between stagnation pressure on the upstream side of a bluff body (sensor) and the static pressure on its downstream side. The output is a differential pressure signal, which is matched with instruments for measuring differential pressure.
It can accurately measure the flow of various liquids, gases, and steam in circular and rectangular pipes and is an ideal substitute for orifice plates and other differential pressure devices in case of large pipe size with its grate advantages including:
- Simple and inexpensive,
- long term accuracy within acceptable limits over wide range of flow,
- low permanent pressure loss
- minimum operating cost
Also an other grate advantage is mentioned for averaging pitot tube is its ability to be installed and removed under pressure when process interruption is expensive or avoided. In such cases retractable pitot tube is one of few flow measurement devices can be used.