A compressor or receiver sold in Great Britain carries either a UKCA mark or a CE mark, and GOV.UK guidance updated on 21 August 2026 accepts either mark for machinery, pressure equipment and simple pressure vessels. You do not need to check whether a machine was marked one way or the other before you buy it, or ask a seller to re-mark stock that already carries a valid CE mark.

Why this matters when you are choosing equipment

The mark tells you the manufacturer has assessed the machine against the relevant safety requirements before it went on the market. A written scheme of examination under the Pressure Systems Safety Regulations 2000, where one applies to your receiver, is a separate duty and sits on top of the marking. Sizing the receiver correctly and knowing whether it crosses the bar-litre threshold is covered on the receiver sizing and 250 bar-litre page.

What to check on the equipment itself

• The mark is present on the compressor and, separately, on the receiver where it is a distinct pressure vessel.
• A data plate is fitted to the receiver, since that plate carries the information a competent person needs when deciding what examination regime applies.
• Any documentation supplied with the machine matches the model and pressure rating on the plate, since a mismatch is the kind of discrepancy worth raising with the seller before installation.

None of this replaces a competent person's assessment of your own installed system. Whether a written scheme is required, and what it should cover, is a judgement made against your receiver's actual bar-litre product and duty.

A receiver's data plate is fixed to the vessel itself, usually stamped or riveted metal, because it has to stay legible for the working life of the vessel it describes.

What's on the plate

• Manufacturer's name and address
• Serial number and year of manufacture
• Volume, in litres
• Maximum allowable pressure (marked PS on the plate) — the highest pressure the vessel is designed to hold, in bar.
• Test pressure applied before the vessel left the works
• The design standard it was built to
• The CE or UKCA mark, with the number of any notified or approved body involved in assessing it

How the 2016 Regulations sort a vessel into a category

The Simple Pressure Vessels (Safety) Regulations 2016 (GB) cover welded vessels made to hold air or nitrogen under pressure, and sort each one into a category set by pressure and volume taken together. A small vessel holding high pressure can store as much energy as a large one holding low pressure, so the two figures are read as a pair. The category a vessel falls into decides which conformity route its manufacturer had to follow before it could carry a mark, and how much of that assessment a notified or approved body had to carry out itself.

That category answers a manufacturing question. It tells you how the vessel was assessed before it was sold. Whether the receiver in front of you needs a written scheme of examination is a separate calculation, based on the bar-litre product of its actual capacity and its actual working pressure, set out in Sizing the Air Receiver, and the 250 Bar-Litre Line. Whether a particular vessel meets the 2016 Regulations, or needs that written scheme, is a judgement for a competent person looking at the vessel itself.

The rules that decide whether a compressor or receiver needs a UKCA mark, a CE mark or both have not stayed still since UKCA was introduced as the Great Britain equivalent of the CE mark. The government has pushed back the point at which UKCA becomes compulsory more than once, and has changed, more than once, whether CE marking on its own is still acceptable for equipment placed on the Great Britain market. A data plate tells you what applied when the machine was built and sold.

What actually shifts

• The date by which a category of pressure equipment must carry a UKCA mark rather than relying on CE alone.
• Whether goods already CE marked can still be placed on the Great Britain market, and under what conditions.
• Which conformity assessment bodies are recognised to issue the certification behind each mark.

None of these move on a fixed schedule you can rely on from memory. A compressor bought two or three years ago may carry a mark that was correct at the time and still legally valid on that machine, while a compressor bought new today needs checking against whatever the current position happens to be.

Why this matters more than the plate suggests

Buying decisions and compliance checks both depend on the rule in force on the day. Treat the plate as a record of what was done, and treat the current requirement as a separate question worth checking each time you buy.