Dispose of Compressed Air Can Safely on Hot Day

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Discussion Overview

The discussion revolves around the safe disposal of compressed air cans, particularly in the context of high temperatures. Participants explore the implications of temperature on the pressure within the cans and the potential risks associated with improper disposal methods.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses concern about disposing of a compressed air can on a hot day, despite the manufacturer's claim that it is safe up to 120°F.
  • Another participant suggests that once the can is empty, the pressure is significantly reduced, implying it is safe to dispose of.
  • A different viewpoint proposes puncturing the can with a tool once it is empty to ensure safety at any temperature.
  • One participant shares an experience of heating a can in boiling water, raising concerns about the potential for catastrophic failure due to high temperatures.
  • A participant discusses the vapor pressure of butane and its implications for pressure inside the can, noting that pressure increases with temperature according to gas laws.
  • Another participant estimates that a safety factor of around 3 could be assumed for failure temperature, but emphasizes that the material strength of the can will degrade at much lower temperatures.
  • Further elaboration on material properties indicates that aluminum alloys lose significant strength at around 600 K, which could be relevant for safety considerations.

Areas of Agreement / Disagreement

Participants express varying levels of concern regarding the safety of compressed air cans at high temperatures, with some suggesting it is safe to dispose of them once empty, while others highlight potential risks and material limitations. No consensus is reached on the absolute safety of disposal methods under high-temperature conditions.

Contextual Notes

Participants reference assumptions about gas laws and material properties, but there are unresolved questions about the exact conditions under which failure might occur and the implications of temperature on can integrity.

Vorde
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For starters, I have no idea where to post this question but I think this is a good place.

Earlier today I bought a compressed can of moisture-less duster to clean my computer fans with. That is all good, but when I was done I wasn't sure where to dispose of the can.

Normally it would be safe to throw in the garbage (its non-toxic in gaseous form) but it's a very hot day (like 90ish) and even though the can says it's safe to temperatures up to 120 I am uneasy about just leaving it in the garbage.

Can anyone advise me here?
Thanks
 
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It should be fine. Once empty the pressure inside is far less than it was when full.
 
That's what I was hoping, thank you.
 
Once you get no more puff out of the can then you can safely use a can opener or chisel to make a hole in the can. It is then harmless at any temperature.
 
Speaking of compressed air cans, if you use them for a few seconds they get very cold, and thus lose their effectiveness.

So once I got the bright idea of putting the can in boiling-hot water to heat it back up. After a few seconds though I got a bit uneasy about the whole deal, for the same reason as OP was about leaving it out on a hot day. Does anybody have any idea how hot these things could really get before catastrophically failing?
 
The vapour pressure of butane is about 2Bar at room temperature (i.e. 1Bar excess) and it's a bit over 15Bar at 100C. That would be significant, I think, if there was still much propellant in the can.

The gas in the can, once the propellant has gone, will only be following the gas laws. The pressure will only increase by around 1/300 for every degree C rise in temperature at room temperature.
 
Lsos said:
Does anybody have any idea how hot these things could really get before catastrophically failing?

I think we could assume the safety factor will be around 3. If there is no liquid phase in the container, then from the ideal gas law we get it should fail at 3x300 K = 900 K. Which is meaningless, because the material of the can will lose its strength much earlier than that. Aluminium alloys, the usual material here, lose 2/3 of their room temperature yield strength at about 600 K.
 
voko said:
I think we could assume the safety factor will be around 3. If there is no liquid phase in the container, then from the ideal gas law we get it should fail at 3x300 K = 900 K. Which is meaningless, because the material of the can will lose its strength much earlier than that. Aluminium alloys, the usual material here, lose 2/3 of their room temperature yield strength at about 600 K.

The plastic bits will go long before that temperature.
 

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