Orifice Flow Measurement

An Orifice Flow Meter is basically a type of flow meter used to measure the rate of flow of Gas, Steam or liquid, using the Differential Pressure Measurement principle. … When this Orifice Plate is placed in a line, a differential pressure is developed across the Orifice Plate.

Orifice Flow meters are a type of a Differential Pressure Flow meters where a flat metal plate (Orifice plate) with an opening in the plate due to this becomes primary flow element and measure flow as a function of differential pressure, placed perpendicular to the flowing stream of gas or steam in a round pipe.

As the flowing gas or steam passes through the orifice, the constraint causes an increase in velocity and decrease in pressure. A differential pressure transmitter is employed to measure pressure among the orifice and the pipe flow stream.  Due to this, there is always a permanent pressure loss. Due to this inherent property (of pressure loss) you cannot use dirty liquids in the orifice flow meters. Orifice differential pressure flow meters are used to measure gas, liquid or steam flow measurements.

Construction of Orifice flow meter:

Orifice flow meter consists of three sections Inlet Section, Orifice Plate, Outlet Section.
Inlet Section: It is an inlet pipe connection extended straight and part of the same diameter for an end connection that serves to the incoming flow of fluid, steam and gas, and where we measure the inlet pressure.
Orifice Plate: An Orifice Plate is positioned in the middle of the Inlet and Outlet Sections to form a pressure dip and hence do the flow measurement.
Outlet Section: Like the inlet section it is an extended straight segment part of the same bore as that of the outlet pipe for an end connection for an outgoing flow of fluid or gas where we measure the pressure of the media at discharge.
The material of construction: The Orifice plates in the Orifice meter, in general, are made up of stainless steel of varying grades like SS 304, 316.
Orifice flow meter size and shapes: Orifice flow meters are constructed in various forms depending on their application-specific requirement i.e., shape, size, and location of holes on the Orifice Plate.

Limitations of Orifice meter:

  • They typically jammed due to unclear liquids and impurities in the gas.
  • Due to inherent vena-contract length for an Orifice Plate there is always a limit on minimum pressure that can be achieved to measure the flow rate.
  • Orifice plate life span is short due to corrosion which corroborated in errors.

Applications of Orifice flow measurement:

  • Automotive industry
  • Water Treatment Plants
  • Oil & Gas industry
  • Petrochemicals and Refineries
  • Textiles
  • Sugar Industries
  • Process Industries

Specifications of Orifice meter:

  • Suitable for all type of Gas like Biogas, LPG, CNG, PNG, Air, Oxygen, Nitrogen etc.
  • Suitable for Saturated and Superheated Steam, Condensate water, HOT water,
  • Data logging facility
  • MOSBUT RTU with RS485 communication port
  • 4-20mA Output

Advantages of Orifice meter:

  • Mass Flow Measure
  • Working in low Velocity
  • Online Density compensation
  • Supply with DPT, RTD, PT , Orifice plate with spool and Gas flow totalizer
  • No moving Parts
  • During installation, no wiring connection required, so installation is very easy