Gas duster mystery

  • #1
PuzzledMonkey
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TL;DR Summary
Why does a gas duster "fizz" when put down but stop when held?
While using an ordinary gas duster (difluoroethane) to clean some electronics, I noticed something weird (see linked videos):
  • After spraying the gas duster and placing it on a hard surface e.g. countertop, the can emits a fizzing noise.
  • Picking up the can causes the fizzing to stop.
  • The process is repeatable i.e. putting the can down starts the fizzing again. This occurs even if the can is placed down very gently.
  • The duster can feels cold to touch, but not painfully so. I'd estimate the can surface temperature as between 0 and 10 C.
  • Difluoroethane has a normal boiling point of -25 C, but the can is pressurized so it could be liquid inside.
  • The fizzing sounds similar to a soft drink, suggesting that the contents could be liquid with some gas bubbles inside.
This is counterintuitive. If the difluoroethane is normally a cold liquid, the heat of my hand or motion of lifting it could vaporize some and cause it to bubble. But what I observe is the exact opposite: removing the hand causes fizzing, while holding the can makes the fizzing stop.

What is going on here?

Gas duster video 1
Gas duster video 2
 
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Answers and Replies

  • #2
DaveC426913
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Is it possible that the hissing is not coming from the can per se, but from the condensation trapped under the convex base? Set the can down, trapped air escapes; lift the can up, no trapped air.
 
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  • #3
PuzzledMonkey
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Is it possible that the hissing is not coming from the can per se, but from the condensation trapped under the convex base? Set the can down, trapped air escapes; lift the can up, no trapped air.

I tried placing the can on its side instead of vertically and sure enough, the noise went away! But this raises another question... while I have no doubt that water is condensing under the convex base, typically condensing water doesn't make the fizzing/bubbling noise that can be heard in the video. Here's a new video with the can on its side.
https://photos.app.goo.gl/ips3kutWC3hCKHFz7
 
  • #4
DaveC426913
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... typically condensing water doesn't make the fizzing/bubbling noise that can be heard in the video.
I was thinking in terms of it bubbling through the imperfect seal between the can and the table.
 
  • #5
rbelli1
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This is likely due to the fact that the countertop has a much larger thermal mass and thermal conductivity to air. More heat equals more boiling. Does placing your hand on the bottom also cause the hissing sound?

BoB
 
  • #6
chemisttree
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Obviously Satan is in that can!
 
  • #7
jack action
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Here is another gas duster mystery: Where does the hissing sound comes from?



(Sorry, I really had another definition of a 'gas duster' when reading the title. It might not be ordinary, but it uses a lot of gas and a blower is involved! :smile:)
 
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  • #8
Tom.G
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Here is another gas duster mystery: Where does the hissing sound comes from?
Sounds like the Gilmer belt (toothed belt) driving the blower. (or a bearing about to seize!)
 

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