Basics of Differential Flow Meter

How Differential Flow Meter Works?

The differential flow meter is the most common device for measuring fluid flow through pipes.

Flow rate and pressure differential of fluids such as gases,vapors and liquids are explored using the orifice plate flow meter.

Types of Differential Flow Meter

The differential flow meter venuri tube,flow nozzle or orifice plate is an inline instrument,that is installed between two flanges .

Orifice Flow Meter

The orifice plate is a flow meter which is comprised of a circular metal disk with a specific hole diameter that reduces the fluid flow in the pipe. Pressure taps are added on each side of the orifice plate to measure the pressure to differential. 

According to the loss of conservation of energy the fluid entering to the pipe must equal the mass leaving the pipe during the same period of time.The velocity of fluid leaving the orifice is greater than the velocity of the fluid entering the orifice.

Working Principle of Differential Flow meter

Applying Bernoulli principle the increase fluid velocity results in a decrease in pressure.As the fluid flow rate increases through the pipe,back pressure on the incoming side increases due to the restriction of the flow created by the orifice plate.The pressure of the fluid at the downstream side of the orifice plate is less than the incoming side due to the accelerated flow.With a known differential pressure and velocity of the fluid the volumetric flow rate can be determined. 

The flow rate “Q” of a fluid through an orifice plate increase in proportion to the square root of the pressure difference on each side multiplied by the K factor. 

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