In various industrial applications, variable area flow meters measure the volumetric flow of liquid and gases. Each flow meter consists of a mobile float and a conical measuring tube. A variable area flow meter works at constant pressure and the displacement area changes according to the volume of liquid passing through the device. The cone and float type design of a typical variable area flow meter is also called a rotameter.

The vertical measuring tube is usually tapered, and the float inside gets pushed up by liquid or gas flow and moves downward due to gravity. The purpose of the float is to increase the area where fluid flows while at the same time maintain pressure. The movement of the float inside the measuring tube determines the fluid flow rate. There are graduations outside the tube which are used to measure the flow rate about the location of the float.

An important application of variable area flow meters

Measuring and monitoring liquid flow rate is important in some applications not only to maintain quality but also to guarantee safety. Fluids have many properties such as viscosity, temperature, and density which needs to be consistently measured to prevent inaccuracies and issues with the desired result.

Variable area flow meters are commonly used in industrial processes such as manufacturing plants which range from food and beverages to pharmaceutical supplies and chemicals. Aside from this, variable area flow meters are also vital in laboratories to monitor liquid and gas flow. In utility industries, a variable area flowmeter monitors filtration loading.

Advantages of using a variable area flow meter

There are some reasons why variable area flow meters are considered the most popular flow meter used today. One notable characteristic is its flexibility. You can use it to measure different kinds of liquids, gas, and even steam. There is no need to use an auxiliary power source which means you can install it anywhere as needed. It is also easy to modify a rotameter to suit different application requirements.

Since rotameters are quite flexible, it follows that they are also cost-effective. These devices have a longer lifespan than other flow meters. You can rely on a rotameter to produce accurate measurements and high repeatability. Variable area flow meters are relatively simple to use and also easy to install.

Are there any disadvantages to using a variable area flow meter?

While it is true that variable area flow meters are the most commonly used liquid flow measuring device used in many industrial applications, there are still some limitations you need to be aware of. Since most rotameters are made from glass, they can be prone to breakage. However, there are manufacturers which can fabricate a variable area flow meter from plastic. Another limitation is that it does not work well when the fluid is opaque because you won’t be able to see the float inside. Lastly, a variable area flow meter is only suitable when installing vertically. Nonetheless, these limitations still do not discount the versatility of variable area flow meters.