The following is some very useful information regarding hydrocarbons which I feel should be noted here.
" The misconceptions of Hydrocarbon flammability.
Due to this misconception, we embarked on an extensive and in-depth search to find and present the facts in reference to Hydrocarbon flammability. We not only want to save the environment we also want people to be around to enjoy it.
The following facts came about:
First and foremost, it is important to recognize that all refrigerants are potentially flammable under certain conditions.
All gases, even R22, is flammable (especially when in the system mixed with the oils) and the right precautions need to be taken when using any refrigerant product. In refrigeration and air conditioning systems which currently use chemical refrigerants, oil is used to mix with the refrigerant and travel around the system. Therefore, all of these chemical refrigerants also become flammable due to the oil vapor content of the gases when being discharged from the systems. Hydrocarbon refrigerants do not spontaneously combust on contact with air! There are 3 elements that all need to coincide at the same time:
1. Hydrocarbons will need to be released.
2. The correct proportion of air needs to mix with the Hydrocarbon, the range of flammability generally being 1.9% to 8.5%. Combustion cannot occur outside these limits.
3. There needs to be some type of ignition source, which exceeds 598°C. If any 1 of these 3 elements isnt present, then the combustion cannot occur.
Generally if there is a leak in a system, only a small percentage of refrigerant will leak out, not the whole amount. Then due to the Hydrocarbon being able to dissipate so quickly, it would be extremely difficult to meet the range of flammability.
In addition, in reference to the frozen food industry, The EPA has given its green light for the use of Hydrocarbon refrigerants for the applications that you desire. Coca Cola, Unilever, Mcdonalds , Pepsico and Redbull have all switched to Hydrocarbons. http://www.refrigerantsnaturally.com/
Good Climate News: USEPA OK's Hydrocarbon Refrigerants For Non-Vehicle Applications : TreeHugger
I hope this information clarifies things."