What are the positive displacement flow meters?

 Email: sales01@cxflowmeter.com

whatsapp: 008618049841995

What are the positive displacement flow meters?

Positive displacement flow meters, also known as fixed displacement flow meters (PD flow meters), are instruments that calculate the total 

flow rate by measuring the number of times a fluid passes through a fixed volume. They are popular for their high accuracy and direct 

measurement of the volume of the fluid. Here are some of the main types of positive displacement flow meters:

Oval gear flow meter: This is one of the most common positive displacement flow meters, mainly composed of two intermeshing oval gears 

and their housing (metering chamber). As the fluid flows, the gears rotate, and each rotation of the gears corresponds to a certain amount 

of fluid passing through.

Waist wheel flow meter (Roots flow meter): Similar to the oval gear flow meter, but the shape and meshing method of the waist wheel (or Roots

 rotor) are different. They also measure the volume of the fluid by rotation.

Scraper flow meter: This flow meter uses a scraper (or rotor) to rotate in the housing, and the scraper extends and retracts along a specific 

trajectory to form a metering chamber. As the scraper rotates, the fluid is metered.

Rotary piston flow meter: The fluid pushes the piston to rotate in the housing, and the volume of the fluid is calculated by measuring the 

number of rotations of the piston.

Reciprocating piston flowmeter: This flowmeter uses a piston to reciprocate in a housing to measure fluid. Each reciprocating motion of the

 piston corresponds to a certain amount of fluid passing through. This type of flowmeter is often used in gas pumps at gas stations.

Disc flowmeter (nutation flowmeter): A disc with a central ball rotates and swings up and down (nutates) in a metering chamber to measure 

the volume of the fluid. This flowmeter is commonly used in domestic water meters and industrial water meters in North America.

Diaphragm gas meter: Although mainly used for gas measurement, diaphragm gas meters can also be considered a positive displacement 

flowmeter. It calculates the volume of the gas by measuring the number of times the gas moves the diaphragm.

Liquid-sealed drum flowmeter (wet gas meter): Used to measure gas flow, it is filled with sealing liquid (such as water or oil), and the drum 

rotates under the push of gas. The total volume of the gas is calculated by measuring the number of rotations of the drum.

These positive displacement flowmeters each have their own characteristics and application scenarios. Users can choose according to specific 

measurement requirements, fluid properties, working environment, and accuracy requirements. It should be noted that although the volumetric

 flowmeter has high accuracy, in some cases (such as when the fluid contains solid particles or high viscosity fluid), it may be necessary to 

choose a specially designed flowmeter to avoid clogging or affect the measurement accuracy.

If you don’t know how to choose a flow meter and what kind of flowmeter is suitable for your on-site working conditions, 

please consult CIXIFM winny:

 Email: sales01@cxflowmeter.com

whatsapp: 008618049841995