Pitot Tube flow Calculator

The pitot tube is one of the flow elements used to measure the velocity of flow in the pipeline, duct, etc. Pitot tubes are widely used due to their small size, cost, and easy installation process. The pitot tube design is based on measuring both static and stagnation pressure of the process in the pipe. The difference between these two pressure measurements gives that dynamic pressure is nothing but the point where the velocity becomes 0 got converted into pressure. The Pitot Tube flow Calculator is designed by this principle.

Mostly pitot tube is used in the air duct, flue gas path, etc to determine the speed of the air where accuracy doesn’t matters. And frequently pitot tube will get stuck by the duct particle present resulting in the purging of the tube often.

As you saw in the above diagram the high and low-pressure sides consist of a hole wave path for pressure measurement. The upstream sensor senses the stagnation pressure of the flowing medium and the downstream senses the static pressure. Both the pressure will act as the second sensing element like the diaphragm in the transmitter. The pressure difference will give you the dynamic pressure which is converted into the velocity of the flowing medium.

On the right side of the diagram, you can see the difference between the static and Stagnation pressure. If you attached a visible straight tube on the top of the pipe during flow conditions, you can able to measure the static pressure. At any point of the pipe, the static pressure will same even for changes in pressure condition.

But at the same time if you insert a simple Pitot Tube, the liquid level rises above the static pressure level. The reason is that the flow velocity once enters the Pitot Tube its speed reduced to zero. The velocity impact rises the water level above the static pressure level. The level above the static pressure is known to be dynamic pressure. And the sum of both the pressure gives you Stagnation.

And the formula derived from the Bernoulli’s equals to determine the velocity is given below.

V = sqrt (2*(stagnation pressure – static pressure )/ density)

   

The below Pitot Tube flow Calculator is used to find the ease of time after inputting all inputs. Click on the calculator image to open.