Orifice meters use steam lines and compressed air for natural gas pipelines. The meter is simple, standard-backed, and cheap to run. It is also not right for every fluid.

This article discusses the appropriate application of orifice plate flow measurement technology and the scenarios in which it is not suitable. It is intended for EHS buyers, plant engineers, and EPC contractors that are looking to select the proper meter.

What Are the Main Orifice Meter Uses?

The primary purposes for which an orifice meter is used include the measurement of the flow rate of clean gases, liquids, and steam. The plate itself has no moving parts, and the process is quite standardized.

Common orifice meter uses include:

Steam: boiler and utility lines.
Natural Gas: Fuel gas, custody transfer.
Clean Liquids: Water, refined hydrocarbons, LPG, and chemicals, as listed by an SPE measurement presentation.
Compressed air and specialty gases: Siemens lists both under their orifice list.
Control and Check Metering: Control signal, check metering, allocation, and process measurement are also listed as non-custody measurements by an SPE deck.

One thing can explain this popularity. In fact, the difference of pressure through an orifice is the most used flow measurement according to the ISA Handbook of Measurement Equations and Tables.

How Does the Orifice Meter Working Principle Explain Its Uses?

The orifice meter working principle needs only a pipe restriction and a pressure reading. That simplicity is why the orifice meter is used in so many industries.

The orifice restriction speeds up the fluid and drops the pressure just after the plate.
Two taps pick up the pressure difference.
A transmitter turns that difference into a flow signal.

Here is the humble math. When flow through an orifice plate doubles, the pressure difference becomes four times bigger, says Automation.com. Pretty neat for a metal disc with a hole.

Which Industries Rely on Orifice Meters the Most?

Oil and gas, power, and process plants lean on them most, because the method is mature and the standards are clear. Each sector uses it a little differently.

Oil and gas: natural gas measurement, from fuel gas to sales gas.
Power and steam plants: steam and feedwater lines.
Chemical & Process Units: Clean liquid and gaseous feeds.
Utilities: Water and compressed air.

Why is this metering system reliable for custody transfer of natural gas?

This is because API MPMS 14.3, which is the same as AGA Report No. 3, dictates the tolerance of the plate, meter run sizes, and inspection.

In custody transfer, money changes hands on the reading, so the rules matter.

Daniel’s orifice fitting guide points to AGA3/API 14.3 and ISO 5167 for custody transfer systems.
For natural gas under API 14.3, a typical beta ratio range is 0.20 to 0.60, according to Industrial Monitor Direct.
An industry standards paper from ASGMT notes that sensors and flow computers cannot tell if the meter run is dirty or damaged, so inspections still count.

Orifice Meter Uses vs. Venturi Meter: Which Fits Better?

The orifice costs less and is simpler to fit. A venturi meter wastes less pressure and handles a wider range, but it costs more.

Factor	Orifice	Venturi
Cost to buy and install	Lower	Higher
Permanent pressure loss	High	Much lower
Typical turndown	3:1 to 5:1	Up to 10:1
Best for	Clean fluids, tighter budgets	Lines where pressure loss hurts

When you compare an orifice and venturi meter for a long-running pump line, count the energy cost too. EngineerExcel covers the trade-offs in more detail.

Where Do Orifice Meter Uses Stop Making Sense?

An orifice meter contracts under circumstances of dirty, viscous, or highly fluctuating flows. Familiarize yourself with the above restrictions before filling out the purchase order.

Slurry and dirty liquids: A flat plate may result in dead areas where solids could be settled (EngineerExcel).
Viscous: An Endress+Hauser user manual restricts viscosity to 50 cSt.
Fluctuating flows: One transmitter provides a turndown ratio of 3:1 to 5:1.

Pressure-sensitive lines: permanent pressure loss is about two-thirds of the measured pressure difference, per Automation.com.
Accuracy requirement: around 1 to 5 percent for simple configuration, and 0.5 to 1.5 percent for compensated installation, as per Pumps & Systems.

What Else Is Required Beside the Plate?

A transmitter, impulse lines, a manifold, and sufficient straight pipe are required.

Skip one and the best plate gives poor numbers.

Transmitter: an orifice type flow transmitter reads the pressure difference. A flow transmitter orifice plate pair is the usual setup.
Plate shape: concentric, eccentric, or segmental. Each orifice plate type suits a different fluid.
Tapping: ISO 5167-2 covers flange, corner, and D and D/2 taps.
Straight run: commonly 25 pipe diameters upstream and 10 downstream. Confirm the exact figure for your layout.
Meter style: Among the types of orifice flow meters, integral and flanged versions suit different lines.

What Should EHS and EPC Teams Check Before Choosing?

Match the meter to the fluid first, then check standards and paperwork. A good match avoids most site surprises.

Fluid is clean, single-phase, and within viscosity limits
The orifice meter uses the fit of the flow range, with turndown checked
Standard named: ISO 5167 for general use, API 14.3 for natural gas custody transfer
Sizing sheet, material certificates, and datasheets on file
Pressure and temperature ratings fit the line
Plate inspection plan: one industry guide suggests about every 5 years in clean service and every 1 to 2 years in erosive or fouling service

Optional read: if leak safety is also on your plate, see this guide on how to choose an infrared gas detector for methane, propane, and LPG leaks.

FAQs

1. How does the orifice meter function?
It is used to measure the flow rate of clean fluids, gases, and steam.

2. How is the orifice meter used for oil and gas?
It is used to measure the flow rate of natural gas, including custody transfer using API MPMS 14.3 and AGA Report No. 3.

3. What is the difference between an orifice meter and venturi meter?
The orifice meter is cheaper but has higher pressure loss compared to the venturi meter, which is more expensive but has lower pressure loss.

4. Can an orifice meter measure steam?
Yes, with condensate pots and a correct impulse line layout.

5. Which fluids should you avoid with an orifice meter?
Slurries and heavily dirty fluids, because solids can settle behind the plate.

6. How often should an orifice plate be inspected?
About every 5 years in clean service and every 1 to 2 years in erosive service, per one industry guide.

Ready to Match the Meter to Your Line?

Share your fluid, pipe size, pressure, and temperature with the team at pcd-flowmeter.com to check which orifice meter fits your application.

Orifice Meter Uses: Where Differential Pressure Flow Measurement Fits Best