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Some inconveniant facts about HC refrigerants

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  • Some inconveniant facts about HC refrigerants

    Sold as "drop in replacements" HC12a etc
    Most seam to be a mix of propane, iso butane and butane sometimes with other stuff mixed in, all are flammable.
    "well my car carries 20 gal of gas, a pound or two of refrigerant gas is nothing when compared to that"
    Here is why that statement is wrong. Gasoline is a liquid at atmospheric pressure and must first evaporate to a vapor/gasous form before mixing with air to form a combustible mixture.
    Most cars carry between 1.5 lbs and 4 lbs of refrigerant, the older R12 cars (the ones that HC12a are marketed too) tend to be on the higher end of that amount. Propane is 4.25 lbs/gal iso butane 4.6lbs/gal and butane 4.9 lbs/gal.
    So even if your system is nearer the lower end you have the gasoline equivalent about 1/2 gal of flammable gas in the system. Unlike gasoline, at atmospheric pressure those gases are in gas/vapor form and can immediately mix with air to form an explosive mixture, they don't have to evaporate from the liquid state 1st.
    So would you be comfortable riding in a car that someone poured 1/2 gal of gas into a pan, then heated it until it all boiled? Not me!
    I worked on gaseous fueled engines and there are a whole bunch of safeguards to prevent them from going "boom". Still, they are more dangerous than gasoline which is more than diesel.
    No sane person would dump between 1/2 and 1 gal of gasoline on the car rug and take it for a drive, but that is what you are doing with flammable gas in a pressurized system. As long as it stays in the system where air (oxygen) is excluded is is harmless, as soon as it escapes into the air, it is not. All it takes is one spark to set it off.
    A crash can rupture pipes and there are plenty of ignition sources in a crash.
    I am not here to tell you what you can and can not do, but it is my opinion that it isn't worth the risk.
    In refrigeration there are "classes" of refrigerant. It used to be there were just two "A" and "B". Class B were those that were flammable (propane) or otherwise hazardous like ammonia. Class "A" were safe for use in inhabited spaces. Since global warming and ozone became a issue, some compromises have been made and now refrigerants that are "somewhat" flammable (Class A-2) are being allowed. HC refrigerants remain in Class B as they are highly flammable.
    To use them as a replacement in say your home fridge, where the total amount is low and the amount of air in the house is large, any leak would dissipate below the flammable limits. Also home fridges don't get in high speed crashes. HC refrigerants are safe in these applications.
    Differing countries take different stands on this. Canada says it is up to you to understand the risks, and make your choice, US has been more restrictive as far as use in motor vehicles.