Contrec 505 – FO01

Open Channel Flow Computer, Tailored for Frequency Flow Meters

The 505 FO01 application measures the flow of fluid in an open channel by using a frequency flowmeter with a velocity proportional output and a 4-20 mA level input. The level input in conjunction with entered dimensional parameters is used to determine the cross-sectional area of the fluid in the channel.

Several channel types are catered for including: Rectangular, Triangular, Trapezoidal, Circular and Half-round. Flow can also be measured in other channel shapes with a Non-linear selection that allows the level input to represent the actual cross-sectional area of the fluid at various levels.


The volume calculation is based on the multiplication of the cross- sectional area and the velocity of the fluid in the channel.

Volume flow = Velocity x Area

The area for one of the selectable channel shapes is derived from the channel dimensions (width, base or diameter) and the input from the level sensor. For “non-linear” channels, parameters are available to allow the area to be read directly from the level input via a series of correction points.