17 May 2023

Volumetric flow meter: how it works, main types and solutions

Volumetric Flow Meter (1)

What is a volumetric flow meter and how does it work? Why is it so important for fluid measurement in the oil industry? 


Flowrate is one of the essential parameters measured in process industries such as oil and gas. For example, in truck loading and unloading processes, the volume of fuel has to be controlled and measured in compliance with national and international laws. 


What is a volumetric flow meter?

A volumetric meter is a flowrate measuring device used to determine a liquid's linear volumetric flow. They aim to improve accuracy, and resolution of fluid measurement.

They result in a great investment to improve efficiency, have low maintenance, are easy to use, versatile and durable. ISOIL offers Positive Displacement meters (PD meters), a type of flow meter that requires the fluid to mechanically displace components inside the meter for flow measurement.


Are you in need of a volumetric flow meter or just want more information? 

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How does a flow meter work?

Volumetric flow meters are the only flow-measuring technology to directly measure the volume of fluid that passes through the flow meter itself. By flowing from the manifold to the body of the meter, fluid fills a high-precision chamber and makes the rotor inside it rotate. Since the amount of fluid that can be contained in this chamber is a known volume of fluid, the volume passing through the meter can be calculated by multiplying the number of rotations by the measuring chamber volume.

 Mechanical positive displacement meters rely on rotation to drive a magnetic coupling or a direct gear train connected to the mechanical counter. If paired with a pulse emitter mounted on the front cover, the meter can also be connected to an electronic counter.


PD flow meters do not require a power supply for their operation and they do not require straight upstream and downstream pipe runs.

Volumetric flow meter types and working principle

Volumetric flow meters are very accurate and have high turndown. They require no straight pipe runs for fluid flow stream and they are not sensitive to vibrations nor to the flow profile.


ISOIL PD meters are divided into categories according to the materials of the body, their construction, and their working principle.


Stainless steel volumetric flow meters (2’’ – 6’’)


Stainless Steel (3)

This volumetric flow meter is made of stainless steel 316, for greater resistance. It is available for different applications: chemical, petrochemical, food industry, etc…. 

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Single Case volumetric flow meters (1 ½’’ – 8’’)

Single Case (3)

Single case volumetric flow meters are the broadest range of ISOIL solutions for measurement. They can be made of different materials, such as aluminum or carbon steel depending on the size and use. They can be installed horizontally or vertically.

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Double Case volumetric flow meters (3’’ – 10’’)

Double Case (2)

The double case design allows this volumetric flow meter to be immune to pressure variations, making it more reliable and accurate. Double case pd meters are composed of an outer body that surrounds the internal one (the measuring chamber) and bares the entire pressure difference between the liquid pressure and the external pressure. 

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Gravity flow meters (3’’ – 4’’)

Gravity (1)

Gravity volumetric flow meters are used when there is no pump, and the liquid flows by gravity. They ensure a very small pressure difference, to work under a limited inlet pressure and can handle the presence of air which is usually present in the fluid during unloading operations.

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Pump & Gravity flow meters (3’’ – 4’’)

Up&Gravity (1)

Do you need more flexibility? A pump & Gravity flow meter is the right solution. It has a very small pressure drop and is capable of operating under a limited inlet pressure when the delivery is taken by gravity or pump. It can also work in combination with a pump to handle the presence of the air slugs which is usually present in the fluid during unloading operations.

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The advantages of choosing ISOIL

For decades in the industry, ISOIL has had undoubted advantages over its competitors, first of all, the accuracy of its measuring instruments, calibrated according to more stringent parameters than those required. In addition, relying ISOIL portrait relies on: 

  • Support - ISOIL follows the entire process at 360°, even after installation ensures all the assistance necessary to grant efficiency and safety for customers. 
  • Custom Tailor-Made solutions - ISOIL stands out for its ability to customize products based on the Customers’ specific requests, even when they differ from standard.


Discover more about our volumetric flow meters

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