A written scheme of examination is a legal requirement for
almost all compressed air systems, yet many compressed air
users seem unaware of the legislation. It can often be
unclear as to where the responsibility lies to ensure
compliance. Andy Jones, general manager of Mattei
Compressors, throws some light on the subject

The Pressure Systems Safety
Regulations 2000 that came into force
on 21 February 2000 outlines the
responsibilities of users and owners of
pressure systems. The regulations state that
users and owners need to demonstrate they
know the safe operating limits, pressure and
temperature of their systems, and that the
systems are safe under those conditions.

The regulations also state that users of
pressure systems must have a
written scheme of
examination, which is a
document containing
information about certain
items of plant and
equipment that form a
pressure system, operate
under pressure and contain
a relevant fluid. A ‘relevant
fluid’ is defined by the
scheme of examination as
compressed air or liquefied
gas, including air at a
pressure of more than 0.5
bar above atmospheric
pressure; pressurised hot
water above 110°C; and steam
at any pressure.

By taking into
account this
definition,
compressed air
systems containing
a pressure vessel
should therefore be
covered by a
written scheme of examination. However,
there is an exception for systems with a
pressure vessel containing less that 250 bar
litres.

In Mattei’s experience, it seems many
compressed air users are not aware of this
legal requirement. But, with a potential fine
of up to £20,000 for not having this
document in place, it is certainly in the best
interests of those responsible for compressed
air systems to ensure it is arranged.

The written scheme of examination
contains a wealth of important information.

Details within the document will include the
parts of the system that need to be
examined, the nature of the examinations,
the preparatory work required and the
maximum length of time between them.

Another important aspect of the document
is the identification of the competent person
who has certified the written scheme of
examination.

It is not just a legal obligation to have the
document, but also to carry out the
examination of the compressed air system in
line with terms and conditions it sets out.

Not doing this is also illegal, and those
responsible will be liable for prosecution.

Therefore, once the written scheme is drafted
and signed off, it essentially needs to become
a working document to provide guidelines
and timescales for the examinations to take
place.

Turning to the issue of responsibility, the
user of the installed system has to ensure the
scheme has been produced. It is the
responsibility of the owner to ensure the
system is not used until the document is
finished and the system examined. To get a
scheme drawn up, a competent person has to
either write the document, or certify it is
suitable. However, the person carrying out
the examinations does not have to be the one
who prepared or certified the written
scheme.

This said, the law does differ slightly if the
compressor is a piece of mobile hire
equipment. In this instance, the
responsibility lies with the owner – ie the
rental company. It is their responsibility to
ensure all the necessary documentation is in
place and the system is checked and
maintained in line with the written scheme
of examination.

For those compressed air users who are
new to this legislation, there are
opportunities to seek help. Responsible
compressed air companies, such as Mattei,
will be able to provide the document and
carry out examinations in accordance with
the written scheme, or at the very least
provide advice on sourcing services.

While the document may seem like a
paperwork exercise, the regulation has been
introduced for good reason. Incorrectly
designed or maintained air systems have the
potential to be dangerous, with the main
hazards being the impact from the blast if a
system explodes, the impact from parts of
equipment that fail, or any flying debris. By
ensuring the system is installed and then
maintained to a high standard at the right
intervals – which the written scheme of
examination will outline – it is possible to
significantly reduce this risk. Having the
scheme in place will also ensure the
responsible person is not at risk of breaking
the law, which could result in prosecution
and a hefty fine. With so many compressed
air companies available to help, there is no
excuse not to comply with this important
legislation.