Flow rate is calculated by a man wearing a yellow safety helmet and carrying a tablet in a plant.

Millions of cubic metres of liquids or gases flow through the pipes of industrial processes every day. In order to be able to transport, control and monitor these correctly, the flow rate must be calculated beforehand.

The flow rate, also called volume flow, is a physical quantity. It defines how much volume of a medium is passed through a cross-section within a certain unit of time.

How can the flow rate be calculated?

The flow rate or volume flow of a medium is determined using the following flow calculation. The prerequisite for this is that the flow velocity of the medium (v) and the cross-sectional area of the pipe (A) are known. The formula for the volume flow (q) is:

Volume flow = cross-sectional area of the pipe * (average) flow velocity (q = A * v)

What factors influence the flow rate?

The right choice of measurement technology depends on the application and the process medium. The temperature, the process pressure and the viscosity of the medium play a crucial role.

What options are there to monitor the flow rate?

With the help of flow switches, also known as flow monitors, the flow of gaseous or liquid media can be monitored. However, mechanical flow switches that work with a paddle do not measure the flow rate. They only detect whether there is a flow or not. Electronic flow switches, on the other hand, use the cooling of a heated element to measure the local flow velocity of a fluid in a pipeline. The calculation of the flow rate is therefore possible with known flow conditions and pipe cross-sections.

In addition to flow switches, WIKA also has primary flow elements in its range. These are used to measure the exact flow values of liquids and gases. Finally, it is possible to use WIKA air flow sensors to measure the total pressure, the static pressure and the average air speed in ventilation and air-conditioning applications.

A selection of our products, and also further technical information on flow switches, primary flow elements, ultrasonic flow meters, electromagnetic flow meters and air flow sensors can be found on the WIKA website. If you have any questions, your contact will gladly help you.

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