Posted By Jane Blunt 'Cracking' or 'snifting' is pretty common practice. It is not a safe practice, however. There is a big risk from the high speed gas that emerges - if you get any part of your anatomy in the way you could get a serious injury. On no account must people deflect the gas stream with their hands. There is also a high level of noise associated with the practice. Last of all, if the gas is hydrogen it can ignite spontaneously. And of course it should go without saying that you should not snift a cylinder of a toxic gas. Regards Jane

Posted By Stuart Bower Thanks Jane & Merv, For anyone else who's interested HSG 139 (2002) actually recommends when connecting new oxygen supplies 'slowly open the cylinder valve, then quickly close it again to dislodge any contamination from within the cylinder valve.' Hmmm - small particles dislodged by nearly 2000 psi. Have to admit to being surprised this is actually recommended practice. Any risk assessment 'banning' this practice may have difficulty in enforcement? What about the use of blanking plugs etc. to prevent ingress of dirt etc? I'm sure there are some out there who know better than me!! Stuart