I am familiar with dry ice, but am not familiar with the application that you describe. Could you explain a bit more, and in particular how the dry ice is used, and what sort of quantity you have and in what environment (ventilation etc).

You don't say how much. 1 kg carbon dioxide produces 845 litres of gas. It is toxic at 4% in air, and fatal at 7% in air. There is an exposure limit of 0.5% If you are going to monitor, do NOT use an oxygen monitor as it reaches dangerous concentrations before the oxygen level is significantly compromised. Use a proper CO2 monitor (easiy to find, since it is an issue in public houses!).

Authoritative information from BOC:- Dry Ice Safety http://www.boconline.co....nes-dry-ice410_39415.pdf http://www.boconline.co....fety/dry-ice-safety.html Storage and Transportation of Dry Ice http://www.boconline.co....-and-transportation.html

thank you everyone this was really useful

I used to work for a company that manufactured technical ceramics. I brought in a specialist company (located in the south of Scotland, as I recall - it was a while ago) to clean down a spray drier after someone had messed with the controls and got it overheated, so the powder got welded to the metal sides (like the proverbial **** to a blanket). Conventional jet washing at 10,000 psi would hardly touch it, but dry ice eventually did. A very effective technique and would recommend it to anyone. Being a bit of an enclosed vessel, the contractor had their own RPE and they were specialists at this game. This sounds like you maybe plan to do it yourselves, so consider the local environment that you are doing it in as other posters suggests with respect to asphyxiation risk. And yes, it is very noisy indeed, so I'd suggest taking a reading and reviewing the hearing protection being used in the area for attenuation levels. Debris coming off this is also a key issue! Luckily we could just hose it all down and it went off to our effluent treatment plant. You may not be so lucky.