Variable area flow meters operate on the principle that the variation in area of flow stream required to produce a constant pressure differential is proportional to the flow rate. The flowing fluid enters the bottom of the meter, passes upward through a variable area metering tube, and around the float, exiting at the top. The flow rate is read by noting the position of the float against the calibrated scale etched on the tube.
Advantages Relative low cost and ease of installation:
Robust and easy to maintain
Applicable to liquids and gases
No need for auxiliary power
Eliminates Ex protection and electromagnetic compatibility issues
VA flow meters are proving popular for a wide variety of transparent liquid and gas applications. As well as general purpose meters, design options are available for rugged environments, high temperatures & pressures. The range is summarised below:
F VA Trogflux variable area flow meter: general-purpose, low cost, plastic VA meter for transparent liquids & gases and non-demanding applications.
F VA Tubux variable area flow meter: variable area flow meter that is compatible with many chemical substances and can withstand temperatures up to 150 deg C.
F VA Unox variable area flow meter: metal Rotameter for liquids & gases that is compatible with many chemical substances and can withstand temperatures up to 150 deg C; it allows installation or removal of the flow tube without removal of the fitting.
F VA Minix variable area flow meter: aluminium VA meters with built-in needle valve for manual control of flow rates; the series can measure liquid flow rates up to 500 m³/hr and gas flow rates up to 8000 m³/hr.
F VA 250 variable area flow meter: all metal variable area flow meter for rugged environments, featuring a robust stainless steel design for use with aggressive fluids up to 300 deg C and 16 Bar.