Flow · Comparison

Orifice Plate vs Venturi Meter

Side by side comparison: how they work, where each fits, and which to choose.

Quick answer: An orifice plate is cheap and standard but loses most of its DP; a venturi costs more and is longer but recovers most of the pressure and resists wear.

Orifice Plate vs Venturi Meter: Comparison Table

Aspect	Orifice Plate	Venturi Meter
Design	Thin plate with a sharp edged bore	Converging cone, throat, diverging cone
Discharge coefficient	about 0.6	about 0.98 to 0.995
Permanent pressure loss	about 40 to 95 % of DP	about 5 to 20 % of DP
Standard	ISO 5167-2	ISO 5167-4
Length	Very short	Long
Wear and dirt	Edge wears, accuracy shifts	Robust
Cost	Low	High

Choose Orifice Plate when

Clean fluids, small and medium lines, low cost
Easy replacement and resizing

Choose Venturi Meter when

Large water and air lines where pumping energy matters
Dirty fluids that would wear an orifice edge

Key Differences Explained

Both create a DP proportional to the square of flow and are calculated with ISO 5167. The venturi smooth shape gives a coefficient near 1 and recovers pressure in its diffuser.

Over years, the energy saved by a venturi on a large line can exceed its higher price.

Related Glossary Terms

GlossaryOrifice PlateAn orifice plate is a thin plate with a precise bore clamped in a pipe; the DP across it is used to…GlossaryVenturi TubeA venturi tube is a DP flow element with a smooth converging inlet, a throat and a diverging outlet…GlossaryPermanent Pressure LossPermanent pressure loss is the part of the DP across a flow element that is not recovered downstream…GlossaryDischarge CoefficientDischarge coefficient is the ratio of actual flow to the theoretical flow through a DP flow element.GlossaryBeta RatioBeta ratio is the bore diameter of an orifice, nozzle or venturi throat divided by the pipe internal…

Free Calculators

CalculatorOrifice Flow CalculatorFree online calculator with formula and worked example.CalculatorVenturi Flow CalculatorFree online calculator with formula and worked example.CalculatorOrifice Pressure Loss CalculatorFree online calculator with formula and worked example.

Free Downloads

Free downloadOrifice Flow Calculation Excel SheetFree download in Excel and PDF.

Frequently Asked Questions

What is the difference between Orifice Plate and Venturi Meter?

An orifice plate is cheap and standard but loses most of its DP; a venturi costs more and is longer but recovers most of the pressure and resists wear.

Is a venturi more accurate?

Uncertainties are similar for standard designs; venturis keep their accuracy longer in dirty service.

Can I swap an orifice for a venturi?

Only with new sizing and enough straight length; the DP range changes.

What about flow nozzles?

They are in between: higher coefficient than orifices, less recovery than venturis.

Learn more on the blog

Mistakes in DP flow measurement

A practical guide on instrumentationblog.in that goes deeper into this topic with field examples.

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