R290 analysis by Danfoss
 

I found this interesting paper about R290 (propane) as a refrigerant in small systems. I had been looking around for information on the concentration at which propane becomes explosive - this paper has a lot of other good info too:

http://www.danfoss.dk/pdf/installato...d/cn60f102.pdf

Enjoy!

Interesting, and puzzling!

My favorite: "Conversion of a R 22, R 502 or R 134a system to R 290 is not recommended by Danfoss, because these systems are not approved for flammable refrigerant use, so electrical safety
is not proven to be according to the needed standards."

It makes me wonder what is needed to meet the "needed standard".

re: puzzling
 

There's a few diagrams where they show ideal placement of the thermostat/electrical switches to minimize the danger of explosion in case of a gas leak into a confined space like the inside of an icebox.

I think this is what they're talking about - normally the charge in these systems is so small that a leak would not be dangerous...but if it leaked into a confined space with an ignition source you could be in trouble!

However, based on the information that article contains about the size of the charge needed in a small R290 system and the LEL (lower explosive limit) the danger of explosion seems nonexistent in the kind of setups we run

*disclaimer, if you've ever seen a butane lighter thrown into a camp fire, you know that even a tiny amount of a flammable substance under the right circumstances can be VERY dangerous...be careful friends :)*