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BGN Variable Area flow meters for gases and liquids

BGN Variable Area flow meters for gases and liquids

Quick Overview

The BGN range of metal tube variable area flow meters are suitable for measuring a wide range of liquids and gases including hazardous chemicals. With stainless steel body, and visual indicator. Accuracy ±1.6 %. With ANSI 150 flanges, sizes 1/2 to 4 . Available with 4-20mA output and relay outputs, with Ex option.
Hazardous Area Approved
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As opposed to the 'fixed float diameter tapered tube' principle used in conventional variable area meters, the BGN utilises a fixed sharp edged orifice and tapered profiled float, the float profile being machined to exacting standards to ensure a linear scaling.

Operating pressures are largely limited only by the flange ratings, and elevated temperature operation is possible by extending the indicator coupling to remove the indicator and associated electrical or pneumatic transmitters from the source of heat.

Large scale production and exacting machining specifications enable all parts of the flow meter to be mechanically interchangeable within a specific range
size, and range conversions and replacement of indicators can be carried out by any skilled engineer without difficulty.

Electrical transmitting system, or high and low alarm contact devices may be fitted in minutes within the indicator housing.

Operating principle
The measuring system comprises a sharp edged fixed orifice ring, and a tapered float.

When the fluid flows vertically upwards, the float rises until a point of equilibrium is reached where the weight of the float is balanced by the buoyancy force 'A'.

This results in an annulus 'S' the area of which is directly proportional to the flow rate.
The vertical movement of the float is transmitted to an external indicator through a magnetic coupling system such that glands and seals are avoided.


  • Simple robust and low maintenance all metal design.
  • High pressure and temperature resistance. Suitable for steam tracing.
  • Linear flow indicator and output signals.
  • Short length of 250 mm enables versatile application in all industries.

Availability: Stock Item


Components / Downloads

For further information, technical advice, or a quotation please call or email us. If you are not sure which product you need one of our technical sales advisors will be happy to discuss your application. We also accept company purchase orders by fax or post. Credit card orders can also be placed over the phone for any product.

BGN Variable Area Flow Meters
Model BGN flow meter, variable area type, stainless steel body, with visual indicator. Accuracy ±2 %. With ANSI 150 flanges, sizes ½" to 4". Simple device suitable for use in a hazardous area.
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