4 ms·

In a pinch you can also use a can of compressed air (not actually air) held upside down.

userbinator 8y ago
Chances are the substance in "canned air" is the same as in "freeze spray" --- a hydrofluorocarbon refrigerant. (They used to be a CFC, before those were banned for ozone layer depletion.)
- ncmncm 8y ago
  It is not widely known that HFCs are a really, really terrible greenhouse gas, with hundreds of times the infrared-retaining power of CO2 and hundreds of times the half-life in the atmosphere. It is estimated that if all the HFCs currently in use ends up vented, it would account for half the total greenhouse effect. It's really important to make sure A/C systems don't leak. If you are ever in a position to specify a big system, get one that uses ammonia.
  - semi-extrinsic 8y ago
    > get one that uses ammonia ... or CO2, or hydrocarbons. The general term is "natural working fluids". But yes, a thousand times this.
    - userbinator 8y ago
      Ammonia is toxic, hydrocarbons are flammable, and CO2 requires extremely high working pressures meaning more expensive equipment and lower efficiency. It's not surprising that before ozone depletion and global warming were known, CFCs became the refrigerant to use, since they're almost completely inert and work at low pressures.
      - semi-extrinsic 8y ago
        I agree that the CFCs have some nice properties. But the new generation of synthetic refrigerants like R1234 are not nice, they are flammable AND they form nice things like hydrofluoric acid when they burn. CO2 is widely used in Japan in vending machines you find everywhere, it's widespread in supermarket refrigeration systems, and it's looking to be the refrigerant of choice for next-gen EVs. It's already what Mercedes use for the AC i the S-class. Hydrocarbons are flammable, yes, but the amount used for a residential unit like a refrigerator is less than what's in your can of lighter fluid in the cupboard. For a commercial kitchen, people have no problem with multiple 10 kg cylinders of hydrocarbon for cooking, but a few hundred grams in the refrigeration system is very dangerous?
  - Cthulhu_ 8y ago
    That's why it's super important to have a good infrastructure for deconstructing and safely emptying AC units and refrigerations. Older models use the nasty stuff that broke down the ozone layer, glad that has been banned at least.
- Cthulhu_ 8y ago
  Wouldn't just compressed air (the same stuff we breathe) be good enough? Actually, in places where compressed air is used frequently, why not use a compressor? Much more renewable. I can imagine regular compressed air causes static electricity or something though so maybe a system that negates that (and filters the air)?
  - pjc50 8y ago
    Much of the cooling comes from a phase change - the reason it works well as a freeze spray is the same as its use in a refrigerant. The can contains liquid which boils. To get the same effect with compressed air you'd need much higher pressure.
neilv 8y ago
It's maybe worth mentioning that people doing that trick with duster gas (such as R-134a) should avoid freezing any body parts, and should also try not to breathe much of the gas.
- BenjiWiebe 8y ago
  Is r134a that bad for you? It's the aerosol in by Albuterol inhaler (for asthma.)
  - neilv 8y ago
    R-134a is just one of the possibilities in duster gas, [1] but none of them are great to be inhaling. [1] https://en.wikipedia.org/wiki/Gas_duster https://en.wikipedia.org/wiki/Gas_duster
  - Reason077 8y ago
    R134a is being phased out in automotive AC systems due to its high global warming potential. It’s being replaced by R1234yf, and in the newest systems, CO2 (aka R744). I would hope it’s not being used unnecessarily as an aerosol in things like air dusters!
  - userbinator 8y ago
    The danger is that it's an asphyxiant --- like most other gases. Otherwise it is inert, which is why it is used. Inhaling a small quantity such as from a dose of an inhaler would not be harmful.

Chances are the substance in "canned air" is the same as in "freeze spray" --- a hydrofluorocarbon refrigerant. (They used to be a CFC, before those were banned for ozone layer depletion.)

ncmncm 8y ago
It is not widely known that HFCs are a really, really terrible greenhouse gas, with hundreds of times the infrared-retaining power of CO2 and hundreds of times the half-life in the atmosphere. It is estimated that if all the HFCs currently in use ends up vented, it would account for half the total greenhouse effect. It's really important to make sure A/C systems don't leak. If you are ever in a position to specify a big system, get one that uses ammonia.
- semi-extrinsic 8y ago
  > get one that uses ammonia ... or CO2, or hydrocarbons. The general term is "natural working fluids". But yes, a thousand times this.
  - userbinator 8y ago
    Ammonia is toxic, hydrocarbons are flammable, and CO2 requires extremely high working pressures meaning more expensive equipment and lower efficiency. It's not surprising that before ozone depletion and global warming were known, CFCs became the refrigerant to use, since they're almost completely inert and work at low pressures.
    - semi-extrinsic 8y ago
      I agree that the CFCs have some nice properties. But the new generation of synthetic refrigerants like R1234 are not nice, they are flammable AND they form nice things like hydrofluoric acid when they burn. CO2 is widely used in Japan in vending machines you find everywhere, it's widespread in supermarket refrigeration systems, and it's looking to be the refrigerant of choice for next-gen EVs. It's already what Mercedes use for the AC i the S-class. Hydrocarbons are flammable, yes, but the amount used for a residential unit like a refrigerator is less than what's in your can of lighter fluid in the cupboard. For a commercial kitchen, people have no problem with multiple 10 kg cylinders of hydrocarbon for cooking, but a few hundred grams in the refrigeration system is very dangerous?
- Cthulhu_ 8y ago
  That's why it's super important to have a good infrastructure for deconstructing and safely emptying AC units and refrigerations. Older models use the nasty stuff that broke down the ozone layer, glad that has been banned at least.
Cthulhu_ 8y ago
Wouldn't just compressed air (the same stuff we breathe) be good enough? Actually, in places where compressed air is used frequently, why not use a compressor? Much more renewable. I can imagine regular compressed air causes static electricity or something though so maybe a system that negates that (and filters the air)?
- pjc50 8y ago
  Much of the cooling comes from a phase change - the reason it works well as a freeze spray is the same as its use in a refrigerant. The can contains liquid which boils. To get the same effect with compressed air you'd need much higher pressure.

neilv 8y ago

It's maybe worth mentioning that people doing that trick with duster gas (such as R-134a) should avoid freezing any body parts, and should also try not to breathe much of the gas.

BenjiWiebe 8y ago
Is r134a that bad for you? It's the aerosol in by Albuterol inhaler (for asthma.)
- neilv 8y ago
  R-134a is just one of the possibilities in duster gas, [1] but none of them are great to be inhaling. [1] https://en.wikipedia.org/wiki/Gas_duster https://en.wikipedia.org/wiki/Gas_duster
- Reason077 8y ago
  R134a is being phased out in automotive AC systems due to its high global warming potential. It’s being replaced by R1234yf, and in the newest systems, CO2 (aka R744). I would hope it’s not being used unnecessarily as an aerosol in things like air dusters!
- userbinator 8y ago
  The danger is that it's an asphyxiant --- like most other gases. Otherwise it is inert, which is why it is used. Inhaling a small quantity such as from a dose of an inhaler would not be harmful.