A rotameter is a unique type of flow meter which utilizes a rotating float to determine the rate of flow in a system. The float is placed in a tube through which the flowing fluid passes, and it moves up or down according to the rate at which the fluid is flowing.

Most commonly, rotameters are used in applications with lower flow rates, and they serve as a cost-effective flow monitoring tool for both gasses and liquids in many applications.

This kind of flow meter is often called a variable area flow meter due to the fact that it is comprised of a slightly narrowing tube. The float moves vertically within this tube as the fluid enters through the bottom of the tube. The fluid pushes the float upward until the force of gravity on the float equalizes with the force of the fluid on the float. Once these forces come into equilibrium, the float will come to rest at a specific vertical position which corresponds to the rate of the fluid flow.

The vertical tube has graduations marked along its height which are used to visually read the flow rate. When the float comes to rest, the flow rate can be determined by simply finding and reading the graduation with which the float most closely aligns.

For the most part, flow readings are taken visually with rotameters, so they are often made from transparent materials such as glass, making the float visible to an operator. However, some rotameters are fitted with electronic sensors to transfer readings digitally. These rotameters do not need to be transparent and thus can be made of metal or other opaque materials.

These flow meters can also be manufactured in a multiple tube design, allowing them to measure the flow of multiple streams at the same time.

Reverse Flow Inline Flow Meter
Rotameters – Hydra-Check

Rotameters are an excellent option for many different industrial applications due to the simplicity, versatility, and accuracy they provide. Installing and using rotameters is incredibly easy. They can be installed just about anywhere in your fluid flow system since they do not require straight pipe runs, and a flow reading can be made by simply taking a look at where the float is located in the meter.

Rotameters are also very flexible and come in a diverse range of configurations and constructions. Single tube rotameters can be used for essentially any simple flow metering application, while multiple tube rotameters are perfect for more complex applications involving more than one flowing stream. Though they are simple, rotameters still provide exceptionally accurate volumetric flow rate measurements, making them one of the top flow meters in the industry.

When purchasing a rotameter, it is important to consider several different factors and features. You should take into account which type of fluid you will be monitoring; rotameters are more frequently used with non-corrosive materials. Other factors include the number of flowing streams and whether a metering valve is needed for your applications. It is best to consult a flow meter manufacturer with these considerations and your application requirements, and they can help you find the right meter for you!

Rotameter Informational Video