Posted By derek mc Hi, Does anyone have any information on when o2 depletion monitors should be installed. We have one fitted within a room that houses a machine with cda and n2 going to it. The room is not sealed, although it has no air vents. This was fitted some years ago but the safety officer who risk assessed it did not document his findings and has now left. I dont believe one is required, but I am afraid I am missing something here. Is there an ACOP, I have checked Barbour and HSE web sites but cant find anything of use.

Posted By Jon Bradburn You could try the British compressed gases association - you will in all likelyhood be subject to the Pressure Systems Safety Regulations and depending on the system you may find the BCGA CP23 a useful guide. Depending on in house competence you should consider having the system independantly assessed - preferably by someone working to CP23 - a member of BGCA? I assume the cda you mentioned is carbon dioxide - this has its own risks aside from reducing the overall O2 concentration in the room. If you are using liquid Nitrogen you may find HSE press release E229:99 of interest. I am afraid what info I have is paper based and in any event our email is down at the moment - IT - arghh. I could fax the press release if you posted your number - it is specifically related to liquid nitrogen though. Hope this all helps Jon

Posted By MMoran Derek If you are using liquid nitrogen / nitrogen gas cylinders or dry ice / carbon dioxide and the room in question could not handle an air change in sufficient quantity to remove the gas then you need to put in low O2 monitors. Also vents to take away the gas should be at floor level as the vapour phase and gas phase will go down the way first and then build up. You will also have to ensure the sensor if lower down to detect the build up. In these cases the confirned space regs come into play. In effect any gas that depletes the oxygen concentration to create a confined space requires a warning system such as low O2 monitor. Michael