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Calculating Flow Rate and Conversion Factors for Flow Meters and Valves

  • Fluidat is an online calculation software for calculating flow rate and conversion factors for both flow meters and valves
  • Use Fluidat to help select the correct flow meter and better understand how your process works
  • Orifice calculations, vapor generation calculations, and pressure difference calculations can also be performed on Fluidat software

Fluidat, from Bronkhorst, is an online calculation software that is used for calculating flow rate and conversion factors for use with both flow meters and valves. Besides making calculations, you have access to over 1800 different fluid properties and corresponding data.

FLUIDAT: the Online Flow Rate Calculator

When working with fluids and ever-changing process conditions, you can face many challenges. Especially when you try to understand the fluid behavior, depending on actual pressure and temperature conditions in the process. How does the fluid (gas or liquid) behave in your application? What are the requirements for your process? This will influence the choice of your flow meter. So, a correct selection of your flow meter is crucial and understanding how your process works even more.


This is where Fluidat can assist you. Fluidat helps you understand the instruments capability. When pressure or temperature conditions change or even when the medium changes, flows must be converted to the new situation. Fluidat can help you decide if your flow meter is capable to do so. Sometimes we must accept that returning the instrument for recalibration is the only option.

​Calculating Flow Rates

Traditionally, fluid data has been stored in technical handbooks and manuals with graphs and tables of data mentioning fluid properties along with their coefficients. However, this is very inflexible and does not allow immediate access to changing fluid behavior (due to external factors).

Knowing this can be very complex for users, Bronkhorst developed on online flow rate calculator; Fluidat. With this tool you can calculate flow rates and conversion factors for your flow meter and valves.

Gas Conversion Factor

Thermal mass flow meters and flow controllers are very reliable devices, but the accuracy depends on the temperature, pressure and medium. In the ‘gas conversion’ part of Fluidat, the user has to choose a gas to find the conversion factor. This gas should be different than the one the instrument was calibrated for. This gas can be a pure gas, or you can create a gas mixture. 

With this tool, you simply choose the ‘Fluid from’ and ‘Fluid to’ parameters, to find the conversion factor. You can also select your exact model to improve the accuracy of the conversion. The conversion factor can then be applied to the output measurement of the flow controller to know the actual flow of the new gas.

Example of a gas conversion made in FLUIDAT

Orifice Calculation

Flow controllers and pressure controllers are equipped with control valves. The size of the control valve is based on the customer wishes. Inlet pressure, outlet pressure, flow, temperature,  and medium (gas or liquid) are the most important parameters here. The values of these parameters can be recalculated with the orifice calculation tool provided by Fluidat.

When a gas is used with a higher density than the original gas, you can recalculate the flow rate or inlet pressure to reach the maximum flow of the instrument again. When you use a thermal mass flow controller, you should also use the gas conversion tool  in Fluidat.

Example of a CEM calculation in FLUIDAT

Vapor Generation Calculation Tool

Creating a vapor by using a liquid flow, a carrier gas, and a heater is something that Bronkhorst has been doing for years now with CEM (Controlled Evaporation Mixing) systems. 

Our CEM calculation tool makes this very easy. You can calculate whether a liquid can be evaporated at the carrier gas flow rate, pressure, and temperature you have in mind. It is not only pure physics that is applied here, but you can also select the right Bronkhorst CEM model for this evaporation.

Pressure Difference Calculator

With the pressure difference calculator you can calculate and size your ES-FLOW ultrasonic flow meter and mini CORI-FLOW mass flow instruments.

By selecting the instrument and actuator, the program calculates the pressure drop over the instrument and – if you have selected an actuator – the Kv value. After the calculation, you will get an overview with the selected instrument and the calculation of the total error over the complete range of the instrument. This is expressed in a trompet-curve.

Example of a Pressure Difference Calculation in FLUIDAT

FLUIDAT; Your Flow Calculation Tool

Fluidat is a very useful tool if you use Bronkhorst instruments, or if you are interested in the physics of flow measurement and control. However, with Fluidat you can also generate all kinds of gas and liquid properties. Generating vapor and pressure lines is also possible to see whether a medium is in the gas or liquid state at a certain pressure and/or temperature.

Register at to take full advantage of this free online flow rate calculator.

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