Pitot Tube Sea Water Measurement Uncertainty


Thread Starter


Hello everyone,

We use ABB pitot tube (torbar) to measure the sea water in the power plant, but it turns out that the inaccuracy exceed the requirement.

We have calibrated the torbar combined with Rosemount DP transmitter in the water application, and the accuracy is nearly +/- 1%.

But when we installed it in the downstream of the circulating water pump at site (the media is seawater), the accuracy is +/- 10%.

We have considered the density difference between water and sea water, and the upstream/downstream pipe length are also with no problem.

Please make an explanation why difference is so large between the calibration and real application. How to solve this problem?

Wang Zhichao
Turbulence in the medium can dramatically affect the pressure measurement.

To ensure that your are getting laminar flow, make certain that your pressure sensor is a minimum of five diameters downstream of any bend in the piping.