SAFE USE OF MACHINERY - 23.11.2012

Inspecting air compressors and receivers

Legal compliance

You’re aware of specific legal requirements which state that systems such as air compressors must to be examined by an engineer or other competent person at regular intervals. However, you’re not sure what parts of the system need to be inspected and when. What’s to know?

Note. The legislation that applies to compressed air installations is the Pressure Systems Safety Regulations 2000 (PSSR).

What needs to be inspected?

It’s a common misconception that all air compressor systems have to be subjected to a thorough examination at regular intervals. Systems only have to be inspected if there’s an air receiver, which is a pressurised vessel which stores compressed air.

Tip. Some air systems only have two components - a driving motor and an air compressor. The delivery of compressed air is immediate and the need to store air in a pressure vessel isn’t required. Because these systems don’t have an air receiver there’s no need for a thorough examination.

Size matters

Although most air receivers must undergo a thorough examination, some are exempt. The PSSR ask: “Is the pressure multiplied by the volume of the pressure vessel greater than 250 bar litres?” If the answer is “Yes”, then a written scheme of examination and an inspection certificate will need to be issued to comply with the legislation. This calculation takes the pressure rated in bars and this is multiplied by the capacity of the tank in litres.

Tip 1. This information is commonly found on a plate on the receiver, e.g. “Maximum Working Pressure (MWP) 11 bar, 50 litres capacity”. In this example, the MWP is 11 bar multiplied by the 50 litre capacity, which gives a rating of 550 bar litres and therefore needs to be examined under PSSR. If you’re not sure whether your system needs to be inspected, check with the manufacturer/supplier.

Tip 2. As a general rule, air receivers with a diameter in excess of twelve inches, operating at 150 psi will need to comply with the legislation.

How often?

An examination usually takes place once every twelve months. However, the type and frequency is defined by the written scheme, which is agreed with the competent person who will be conducting the examination.

Tip. For the majority of air receivers the first examination is a full, internal thorough inspection. The next one, twelve months later, is a working external check. The following year it requires another thorough examination. This means there’s a requirement for a thorough examination every two years.

Who should complete it?

This isn’t an in-house job. Speak to your insurer or the supplier of the equipment. They’ll be able to arrange for an appropriately qualified engineer to complete the work.