A variable area flow meter or rotameter is a very simple device that measures the flow of most process gases and liquids. As the flow of product increases through the flow meter, the position of the float or needle indicator changes relative to the scale engraved on the flow meter to give a visual indication of the current flow rate that is easily read by the user.

As flow decreases to zero either gravity returns the flow element to its initial resting position or a spring is fitted which performs the same task.

Variable area flow meters are available in various forms. Flow Indicators, Flow Transmitters, Flow Alarms, Viscosity Compensated for Oil service and other options for connection to most process control electronics.

Flow meters wetted parts are manufactured using materials including Aluminium, Brass, Glass, Plastics, PVC, Stainless Steel, etc. The materials of construction offer compatibility to a wide range of industrial process mediums


The plastic tube type flow meters are an economical solution when compared to the glass version, but not as robust and have temperature limitations when compared to a glass model, both styles are suitable for measuring transparent liquids and process gases.


While the cost can be higher, glass has a higher chemical resistance than most plastics and are of a robust design with metal chassis and due to the manufacturing process can offer a higher degree of accuracy.

A number of glass tube Variable Area flow meters can be fitted with needle control valves This option allows the operator to set and adjust flow rates as required.

An economical latching alarm device is also available, this enables the alarm to remain activated whilst flow is above or below a set point. Ideal for remote and process control applications


Metal tube flow meters are great for opaque liquids usually with an external indicator. Due to their construction they are suitable for high pressure and or high temperatures applications. As well as having good chemical resistance with a stainless Steel housing this style of flow meter can be installed into vertical or horizontal piping.

Why choose B.E.S. Flowmeters?

B.E.S. Flowmeters is based in Melbourne and has been providing the highest quality brands to clients since 1986. With long experience in the trade, we stand by supplying only quality brands to our customers from a wide range that offers a huge amount of choice to anyone buying from us, with full technical help and support to ensure you get just the right instrument for the job.

We can supply our variable area flow meters with a needle control valve, or without, for many different applications and products. Our flow meters come in a wide range of materials depending on your application and compatibility

If you’re unsure, simply click over to our Resources web page and check out our helpful PDF Links before buying so you know you’re getting the right flow meter application.

Our range of variable area flow meters includes flow transmitters, flow alarms and switches, calibration cylinders, flow transmitters and more, and you can choose between PVC and stainless steel connections, as well as adding a latching alarm facility if needed.

Whatever your needs, B.E.S. Flowmeters has the products you need and the experience to help you no matter what the job. Contact us today on (03) 5956 8685 or view our full range of variable area flow meters on our website.



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MPB VA Flowmeter Range

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MPB 3500 Series Flowmeter
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