What Is a Rotary Flowmeter?

A rotary flowmeter is an industrial flowmeter used to measure the flow rate of liquids and gases. It consists of a variable area flowmeter composed of a tube and a float. The float's response is linear to changes in flow rate, and the flow range is typically 10:1.

Specifications of Rotary Flowmeters

Rotary flowmeters have a linear scale, a long measurement range, and low pressure drop, making them highly popular in the industry. Additionally, one of the advantages of rotary flowmeters is their easy installation and maintenance. Among the rotary flowmeters available in the market, oxygen rotameters and nitrogen rotameters can be mentioned, which are used to measure the flow rate of oxygen and nitrogen, respectively. Below, we'll discuss the features of rotary flowmeters.

How Does a Rotary Flowmeter Work?

A small annular orifice is located between the float and the tube, and when the pressure due to the flow increases, the float moves to a higher position, increasing the area between the float and the tube. This process continues until hydraulic forces balance with the weight downward. The float moves up and down the tube in proportion to the fluid flow velocity and the annular area between the float and the tube. When the forces reach equilibrium, it settles into a stable position within the tube. As the float moves towards the larger end of the conical tube, the annular opening between the tube and the float increases, reducing the pressure difference across the float.

Types of Rotary Flowmeters

Rotary flowmeters are categorized based on the materials used in their construction. These categories include:

• Glass Rotameters

• Metal Rotameters

• Plastic Rotameters