When an orifice plate is placed in a pipe carrying the fluid whose rate of flow is to be measured, the orifice plate causes a pressure drop which varies with the flow rate. This pressure drop is measured using a differential pressure transmitter and can be used to calculate the flow rate. The orifice, nozzle and venturi flow rate meters use the Bernoulli Equation to calculate fluid flow rate using pressure difference through obstructions in the flow Sponsored Links In a flow metering device based on the Bernoulli Equation the downstream pressure after an obstruction will be lower than the upstream pressure before. www.emerson.com

Equation 1 is the fundamental orifice meter equation. It can be found on page 25 of the 1985 standard and is actually a combination of equations (3) and (7) on that page. Equation 1 describes the theoretical basis, the physical and practical realities of an orifice flow meter. Equation 2, the factored equation, is based on or derived from ...

Units in large bore orifice flow meter for gas flow rate measurement calculation: C=degrees Celsius, cm=centimeter, cP=centipoise, cSt=centistoke, F=degrees Fahrenheit, cfm=cubic feet per minute, cfs=cubic feet per second, ft=foot, g=gram, hr=hour, in=inch, K=degrees Kelvin, kg=kilogram, lb=pound, m=meters, mbar=millibar, min=minute, mm=millimeter, N=Newton, Pa=Pascal, psi=pound per square inch, R=degrees Rankine, s=second, scfm=standard cfm, std=standard. This article provides calculation methods for correlating design, flow rate and pressure loss as a fluid passes through a nozzle or orifice. Nozzles and orifices are often used to deliberately reduce pressure, restrict flow or to measure flow rate.

An orifice plate is basically a thin plate with a hole in the middle. It is usually placed in a pipe in which fluid flows. As fluid flows through the pipe, it has a certain velocity and a certain pressure. When the fluid reaches the orifice plate, with the hole in the middle,... One common method to measure the flow rate in pipe is to insert an orifice plate, nozzle or venturi tube and measure the drop of pressure that arises when the media passes. The formula for the relation between flow and differential pressure can very simplified be stated as:

To calculate flow rate, you have to enter the orifice plate throat diameter as well as pipe interior diameter, together with fluid properties - density and viscosity. For a gas as flowing fluid, instead of the density, you can enter gas constant, pressure and temperature at actual conditions. The orifice equation describes the rate of flow of liquid through an orifice. The equation can be represented as: $ Q = C_{d}A\sqrt{2gh} $ where Q = flow (cubic metres per second) $ C_{d} $ = coefficient of discharge A = area of orifice (square metres) g = acceleration from gravity (9.81 m/s^2) h = head acting on the centreline (m)

This article provides calculation methods for correlating design, flow rate and pressure loss as a fluid passes through a nozzle or orifice. Nozzles and orifices are often used to deliberately reduce pressure, restrict flow or to measure flow rate. Units in large bore orifice flow meter for gas flow rate measurement calculation: C=degrees Celsius, cm=centimeter, cP=centipoise, cSt=centistoke, F=degrees Fahrenheit, cfm=cubic feet per minute, cfs=cubic feet per second, ft=foot, g=gram, hr=hour, in=inch, K=degrees Kelvin, kg=kilogram, lb=pound, m=meters, mbar=millibar, min=minute, mm=millimeter, N=Newton, Pa=Pascal, psi=pound per square inch, R=degrees Rankine, s=second, scfm=standard cfm, std=standard. The American Gas Association (AGA) provides a formula for calculating volumetric flow of any gas using orifice plates in their #3 Report, compensating for changes in gas pressure and temperature. A variation of that formula is shown here (consistent with previous formulae in this section): Equation 1 is the fundamental orifice meter equation. It can be found on page 25 of the 1985 standard and is actually a combination of equations (3) and (7) on that page. Equation 1 describes the theoretical basis, the physical and practical realities of an orifice flow meter. Equation 2, the factored equation, is based on or derived from ... 4 History of Orifice Flow Measurement 5 Gas Law Fundamentals 6 Orifice Gas Flow Equation 7 Critical Flow 8 Major Advantage of Orifice Meter Measurement 9 The Three “R’s” 10 The Orifice Plate 11 Meter Tap Location 12 Primary Element Orifice Flanges 13 Dual-Chamber Orifice Fitting

Orifice plate sizing programs usually allow the user to select the flow equation desired. The orifice plate meter can be made of any material, although stainless steel is the most common. The thickness of the plate used ( 1/8-1/2") is a function of the line size, the process temperature, the pressure, and the differential pressure. ment of the fluid flow equation used almost everywhere in the United States to calculate the rate of flow of natural gas through an orifice. This purpose is accomplished in, essentially, two steps: (1) Starting with the most fundamental relation ships, the Navier-Stokes equations for compressible fluids are derived.