The DFM is a well proven variable area flowmeter for the measurement of clear liquids and gases. It is simple in operation, easy to install and requires no maintenance. It gives you a clear visual display of flow rate and has the option of relay outputs for high and low flow alarm conditions.
When a fluid flows through the vertical tapered metering tube, the float will rise until a point of equilibrium is reached, where the downward weight of the float is balanced by the upward thrust of the fluid. This point will represent a specific flow rate. If the flowrate increases, the float will rise to a new point where the new upward thrust of the fluid is balanced by the weight of the float.
For a given set of fluid conditions, the float will be stable at positions that can be marked on a graduated scale on the tapered tube. These divisions can be calibrated in units of volumetric flow.
The graduated scale depends on three factors:
– the shape and weight of the float
– the size and taper of the measuring tube
– the density and viscosity of the fluid.