Do Air Compressors Need to Be Inspected? Your PSSR Duties
- Nexus Examination
- Jun 26
- 3 min read
Updated: 6 days ago
A compressor that runs fine day after day rarely feels like a safety risk, so it is easy to assume the annual service has it covered. For most compressors, the law says otherwise. Here is a straight answer on whether air compressors need to be inspected, when the duty applies, and why a service is not the same thing.
Do Air Compressors Need to Be Inspected?
Yes. Most air compressors must be inspected by law under the Pressure Systems Safety Regulations 2000 (PSSR). If the air receiver's maximum working pressure in bar multiplied by its volume in litres reaches 250 or more, you need a written scheme of examination and regular examination by a competent person. A routine service does not count.
The reason is simple: compressed air is stored energy, and a receiver that fails can do so violently. We carry out air compressor inspection across Berkshire and the surrounding counties, and it is one of the duties owners most often overlook.
Why Air Compressors Fall Under PSSR
PSSR covers pressure systems containing a relevant fluid above 0.5 bar, and compressed air sits squarely within that. The part that matters most is the air receiver, the pressure vessel that stores the air between the compressor and the tools using it.
That stored energy is exactly what the regulations are concerned with. The air receiver is usually the focus of the examination, alongside the protective devices that keep it within safe limits. The HSE's PSSR guidance sets out the legal framework in full.
The 250 Bar-Litre Rule
Whether you need a formal written scheme comes down to a simple calculation. Multiply the vessel's maximum working pressure in bar by its internal volume in litres. If the result is 250 bar-litres or more, a written scheme of examination is legally required.
To put that in context, a 50-litre receiver running at 10 bar works out at 500 bar-litres, well inside the requirement. A small 10-litre receiver at 10 bar is only 100 bar-litres and falls below the threshold, but you must still keep that system maintained and safe under PSSR. A written scheme, drawn up by a competent person, sets out:
The items covered, such as the receiver, pipework and protective devices
The nature of the examination required for each part
The maximum interval between examinations
Any preparation needed to examine the system safely
The name of the competent person certifying the scheme and the date
Our PSSR examinations include preparing and certifying that scheme where you do not already have one.
What the Inspection Involves
The examination is a structured safety check, not a glance over the machine. Carried out by a competent person at the intervals set in your written scheme, commonly around every 12 months, it typically looks at:
The internal and external condition of the air receiver, where safe to access
The operation of safety and relief valves
The accuracy of pressure gauges and indicators
The function of drain valves and other protective devices
Pipework and joints where a defect could cause danger
Any signs of corrosion, erosion, leaks or abnormal vibration
The competent person then issues a report stating whether the system is safe, with any defects and the action needed. Serious defects that pose imminent danger must be reported to the HSE.
Inspection Is Not the Same as Servicing
This is the misconception we come across most. A service keeps the compressor running well, with oil changes, filters and general upkeep. The PSSR examination is a separate, statutory check focused purely on the pressure risk and the integrity of the system.
A service record cannot stand in for an examination report. If an HSE inspector asks for your written scheme and examination records, a stack of maintenance invoices will not satisfy them.
Who Is Responsible, and What Happens If You Don't
The duty sits with the user or owner of the system. For a hired or mobile compressor, the owner is normally responsible for the written scheme unless you have agreed otherwise, so it is worth checking before you assume you are covered.
Operating a system that needs a written scheme without one is an offence. The HSE can issue improvement and prohibition notices, bring prosecutions, and a missing scheme can invalidate your insurance if something goes wrong. Our thorough examination services keep that side covered, so the system is both legal and genuinely safe to run.
The Bottom Line
Most air compressors need to be inspected. If the receiver reaches 250 bar-litres, you need a written scheme of examination and regular examination by a competent person, and that duty is entirely separate from servicing.
Work out your bar-litres, check whether the owner or you hold the duty, and make sure the scheme is in place before the system is in use. That is what keeps the compressor on the right side of PSSR and safe for the people working near it.
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