Business gas meter types explained

Walk into most shops, offices, cafes and small workshops and the gas meter looks much like a domestic one, just bigger. That is because it usually is: the same family of diaphragm meters covers everything from a house to a busy commercial kitchen. Only once a site’s demand climbs into industrial territory do the meters change technology altogether.

This guide covers the meter types you are likely to have, how to read the size off the front of the meter, and where meter class and consumption thresholds start to matter.

What types of gas meter do businesses use?

Most business premises have a diaphragm meter, sized U6 to U160 depending on how much gas the site can draw at once. Sites with higher flow or pressure needs move on to rotary meters, and the largest industrial users have turbine meters, often paired with a corrector that adjusts the reading automatically. Very large sites are also read daily rather than periodically, and are classed differently for industry settlement purposes.

Which one you have generally follows your consumption:

Typical site	Likely meter type
Small shop, cafe, office	Diaphragm, U6 to U16
Larger kitchen, small hotel, medium retail unit	Diaphragm, U16 to U40
Large retail, light industrial	Diaphragm U65 to U160, or rotary
Heavy industrial, large manufacturing	Rotary or turbine, usually with a corrector

What is a diaphragm meter?

A diaphragm meter measures gas using two or more chambers formed by flexible diaphragms. Gas fills one chamber while it is expelled from another, and the back-and-forth movement drives a crank that turns the dial or index you read. It is the same basic mechanism used in a household meter, just built in larger sizes for bigger gas flows.

What do the U6, U16, U25 sizes mean?

National Gas’s own guidance on identifying meter size explains that these codes describe the meter’s maximum flow rate in cubic metres per hour, shown on the meter as a “Q max” figure. Its example is explicit: where the meter shows “Q max = 6 M3/H”, that is a U6 meter, and “Q max = 16 M3/H” is a U16.

National Gas categorises typical sizes like this:

• U6 covers most standard domestic-style properties.
• U16 is typical for large properties with heavier equipment, such as a commercial kitchen or a heated swimming pool.
• U25 is for premises needing an extremely large hourly gas flow, and National Gas notes these are rarely required.

Commercial diaphragm meters continue upward in the same U-series beyond these three, generally in steps such as U40, U65, U100 and U160, each one handling a higher maximum flow in cubic metres per hour than the last. If your bill or paperwork shows a meter code you cannot place, our guide to meter serial numbers explains the difference between that code and your MPRN.

Where do I find my meter’s size?

Look at the meter face near the dial. National Gas says the size is usually printed close to the index, either as a “U” or “E” code plus a number, or as a “Q max” figure in m³/h that tells you the same thing. If you cannot see it clearly, your supplier or the Meter Asset Manager responsible for your meter (see below) can confirm the size from their records.

What is a rotary meter?

A rotary meter uses two figure-of-eight shaped lobes that spin against each other inside a chamber. Each rotation moves a fixed volume of gas through the meter, and because the mechanism is more precisely machined than a diaphragm meter, it can handle higher pressures and higher flow rates in a smaller physical unit. Sites that have outgrown the largest practical diaphragm meter, or that run at an elevated supply pressure, typically move to a rotary meter instead.

What is a turbine meter?

A turbine meter measures gas flow by tracking the rotational speed of a turbine-like rotor spun by the moving gas. It is generally reserved for the highest flow rates, at large industrial or process sites where even a rotary meter would not have enough capacity. These sites almost always also need a corrector, and are read differently under industry rules, covered below.

What is a corrector, and does my meter need one?

A corrector, or electronic volume corrector, measures the pressure and temperature of the gas passing through a larger meter and automatically adjusts the volume reading to standard conditions, rather than relying on the fixed 1.02264 correction factor used for smaller supplies. Larger commercial and industrial meters are more likely to have a separately identifiable corrector fitted, because pressure and temperature at higher flow rates can vary more than they do through a small diaphragm meter.

Xoserve’s industry glossary confirms that a Meter Asset Manager is responsible for “the gas measuring equipment (meter or corrector)” at a site, treating the two as related but distinct pieces of equipment. If your business has a corrector, our guide to converting a meter reading to kWh explains how the correction factor and calorific value combine to produce your billed kWh figure, whether that correction happens electronically at the meter or is applied by your supplier afterwards.

How does my consumption affect my meter class?

Behind the scenes, every non-domestic gas supply point is assigned an industry meter class that determines how often it is read and settled. Xoserve’s glossary sets out two of these:

• Class 1: a site with an Annual Quantity (AQ) of 58.6 million kWh a year or more, which is mandatorily read daily by a daily meter service provider (DMSP).
• Class 3: a site the shipper (the company that buys and arranges transport of the gas on a supplier’s behalf) has specified to receive meter reads in weekly batches.

Sites below these thresholds are generally “non-daily metered” (NDM), meaning their AQ is estimated between periodic actual readings rather than measured every day. Your AQ is explained in more detail in our guide to MPRN numbers, including how it is calculated and corrected.

In practice, this means the meter technology and the reading frequency tend to move together: a small NDM site with a U16 diaphragm meter might be read every few months, while a Class 1 site with a turbine meter and corrector is read automatically every day.

Do I need a smart or advanced meter?

Government guidance on the non-domestic smart meter rollout says that where annual consumption is expected to be more than 732 MWh (732,000 kWh) a year, supply licence conditions require an advanced meter rather than a standard smart meter. Advanced meters record consumption for multiple time periods and give the supplier remote access to the data, similar to a smart meter but without every smart meter protection applying.

Below that threshold, non-domestic smart meters are being rolled out under a separate supplier obligation. Our guide to smart meters for business covers who has to have one, what happens at installation, and the new rules linking smart meters to fixed-term contracts from September 2027.

Who owns and maintains a business gas meter?

You do not generally own your gas meter. Xoserve’s glossary describes the Meter Asset Manager (MAM) as the company appointed by your supplier to manage the metering equipment, meter or corrector, at your site. The MAM is usually one of a handful of specialist firms rather than your supplier itself, and it is who arranges site visits for meter exchanges, safety checks or fitting a corrector if your consumption grows into a higher meter class.

If you are moving premises and are not sure what meter is already on site, our guide to new business energy connections covers what happens when a gas supply is being connected or transferred for the first time, including who to contact if there is no meter there at all.

Can I ask for my meter to be checked or upgraded?

Yes. If you think your meter is undersized, faulty, or that its class no longer matches how the site is used, contact your supplier first. It will instruct the Meter Asset Manager to inspect, recalibrate or replace the meter as needed. Ofgem’s licence conditions no longer set a fixed inspection cycle for every meter, following a change that removed the previous two-yearly inspection requirement, so most inspections now happen when you request one, when a meter is due for replacement, or when a supplier or transporter identifies a specific issue such as suspected under-recording.

If a meter exchange means moving to a different U-series size, or adding a corrector for the first time, expect the Meter Asset Manager to arrange a site visit, and expect your Annual Quantity to be reviewed once actual readings are available on the new equipment. Our guide to MPRN numbers explains how AQ corrections work and who can request them.

What if my meter size does not match my usage?

If your business has grown, added equipment, or is regularly close to the maximum flow your current meter can pass, it is worth raising this with your supplier before it becomes a problem. An undersized meter can restrict gas flow at peak demand, which shows up as reduced pressure to appliances rather than as anything visible on a bill. Growing into a different meter class can also change how often you are read and how your Annual Quantity is calculated, so it is worth checking your latest AQ figure looks realistic for your current operation.

For everyday billing questions once you know your meter type, our guide to reading a business energy bill explains where meter details typically appear, and when you are ready to see how your gas costs compare, you can compare business energy quotes with us.

Frequently asked questions