I've been trying to research possible canidates for a low stage on a cascade refrigeration build hopefully something easy to get a hold of. i thought i had found something with nitrus oxide but then i found a rather convinsing thread over at xtreme systems forums about how it will react with oil explosively :-( Bummer. I did a google search trying to find a refrigerant number for acetylene but there doesn't appear to be one. http://en.wikipedia.org/wiki/List_of_refrigerants

i found a mention on one site that acetylene reacts with strong bases to form salts or something? i guess oil is a base right? so that sounds like a non starter. kinda a bummer the pressure temp chart i found for it looks like it would be usefull if it was able to be used. it certantly wouldn't be hard to get a hold of! without more information i think i don't want to find out the hard way that it is incompatable. i would think maybe the fact that it doesn't have a refrigerant number is probably a sign that there are issues. just wish there was more info out there..

it seems the budget low stage refrigerant of choice for most builds is R-1150 Ethylene. it has proved dificult to find locally though. as a bonus question has anyone heard of a good online source for ordering it? (and the regulator/piping to charge with it)