Our operations manager had a visit from a local compressor company to look at a system upgrade. The guy happened to notice that we had an air line in a production cell to blow out some tooling when cleaning down the line when changing over batches of work, which happens pretty frequently.

He mentioned that we should be restricting the pressure of this line owing to the danger of blowing into cuts in the skin and creating embolisms (a bit rare, surely, but a chance nevertheless) and said there was a legal requirement to restrict the pressure. I've scoured most of the regs you would probably associate with this (Compressed Air Regs, PSSR and associated ACoPs and guidance etc) and can't seem to find anything on this at all.

We currently do have a valve on the line to drop the pressure (you can still alter it if you really wanted) but I was wondering if we went to a restrictor, what the pressure should be? Surely there is a pressure at which skin wouldn't move when blown (for example), making it safe in this context? Or are there specific restrictors that are pre-set in terms of pressure, for this very purpose? Thoughts and advice most welcome!

Taken from HSE Compressed Air Guide Step 104

http://books.hse.gov.uk/...alogueCode=9780717615315


Blow guns consisting simply of a reduced orifice in direct line with the supply
hose can be extremely dangerous, unless preceeded by a pre-set tamperproof
pressure regulator set at a reduced pressure from the normal 80 psi
airline supply. Models are available commercially which incorporate an air
curtain designed to provide a protective shroud around the nozzle. Although
Compressed air safety Page 25 of 50
Health and Safety
Executive
not completely safe, these designs significantly reduce the risk of eye injury
and the dangers from close skin contact. If designed correctly such nozzles
can often help to prevent the operator from being subjected to excessive
noise. Because air is vented directly into the atmosphere, clean dry air
is essential and lubricators should not be used. Blow guns can exhaust
significant quantities of air and place extra loading on the compressor
system. In view of this and the attendant risk arising from use of blow guns,
their use should be considered carefully with a view to using
alternative
means for cleaning down machinery or components.

Hope that helps

Have you considered the alternative to blowing. There are compressed air operated guns that use the air to create a vacuum and suck up the material to be removed. If you PM me with your e-mail address I can provide you with more information on these. (I have no commercial interest in these guns.)

Chris

We have to recognise that USA Federal (OSHA) and State health & Safety legislation is mostly prescriptive, whereas our legisaltion is not that prescriptive. In my view, a suitable & sufficent risk assessment in the use of compressed air is most likley to conclude that if there is no alternative to the use of compresses air for "cleaning", then the "control measure" would be the use of properly designed "blow guns"

The hazard of effects of compressed air on skin is explicitly highligted in the HSE Guidance, as metioned by Salis from the HSE Guidance:-

"....................Blow guns consisting simply of a reduced orifice in direct line with the supply hose can be extremely dangerous, unless preceeded by a pre-set tamperproof pressure regulator set at a reduced pressure from the normal 80 psi airline supply. Models are available commercially which incorporate an air curtain designed to provide a protective shroud around the nozzle. Although not completely safe, these designs significantly reduce the risk of eye injury and the dangers from close skin contact..........."