What is K Factor in Flow Meters?

In flow measurement, the "K factor" is not as well-known as other flow meters specifications. It refers to the calibration factor associated with volumetric, pulse output flow meters. It is a constant value used to convert the physical flow rate of a media into an electrical or mechanical signal that can be measured and monitored.

The K factor represents the relationship between the flow rate passing through the flow meter and the output signal generated by the meter. It is typically determined through calibration tests performed by the manufacturer or a calibration laboratory.

The formula to calculate flow rate using the K factor is: Flow Rate = K Factor × Output Signal.

Different flow meters have different K factors due to their unique design, operating principles, and construction.

For example, in a turbine flow meter, the K factor is determined by the rotor design, the number of blades, and the geometry of the flow passages. In a magnetic flow meter, the K factor is influenced by the pipe size, the magnetic field strength, and the flow profile.

It's important to note that the K factor may vary under different flow conditions, such as media viscosity, temperature, and pressure. Therefore, it is crucial to consider the application-specific conditions and use the appropriate K factor for accurate flow rate calculations.

Any unit with a pulse output only will either require a nominal K-Factor or an actual K-factor. The K factor is specific to each type and model of flow meter and is usually provided by the manufacturer and is required to calibrate the unit.

For some models the unit comes with a chart of empirically derived data. Other units will have a table with multiple points plotted as flow rate vs. output pulse to help linearize the output data. The K factor is specific to each type and model of flow meter and is usually provided by the manufacturer.

Units with an analog output, such as 4-20mA, and units with a 0-5 Vdc output will not require knowledge of the K factor.