Pressurized Gas Canister Release Question

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In the discussion about pressurized gas canisters, it is established that Canister B, heated to a higher temperature, will have a significantly higher pressure than Canister A. When both canisters are opened, Canister B is expected to empty first due to its greater pressure differential, which allows gas to escape more rapidly. There is some confusion regarding the impact of physical expansion of the canisters versus the expansion of the gas itself, but the consensus leans towards the gas dynamics being the primary concern. The discussion also touches on the definitions of "empty," whether referring to pressure or mass, which adds complexity to the question. Ultimately, the conclusion is that Canister B will likely expel its gas faster due to its higher pressure.
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Hi,

I have 2 pressurized canisters, both are 60 litres in size. Both are filled with 120 litres of ideal gas. Canister A is heated to 100 degrees celcius (373 kelvin) and Canister B is heated to 2000 degrees celcius (2273 Kelvin).
Canister B will obviously expand more than Canister A.
But, I have a few questions.
If both canister valves are opened to release the gas, which canister will empty first? Canister A that has lower volume of gas and lower pressure or Canister B that has larger volume and higher pressure?

Cheers
 
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Assuming the canisters don't expand much (so their volume difference is isn't much and the pressure is high), canister B will be at much higher pressure and will therefore expel it's gas faster on a per mass basis.
 
initial pressure and volume in both canisters are same(not different as you say).
after the heating, pressure of can B will be obviously more. therefore canister B will empty first.
 
ank_gl said:
initial pressure and volume in both canisters are same(not different as you say).
after the heating, pressure of can B will be obviously more. therefore canister B will empty first.
How can two identical containers, with the same amount of gas in them, at two different temperatures have the same pressure?

Are we discussing reality, because, if we are, the flows will be choked coming out of the canisters...
 
Last edited:
i was talking about the state of the containers before heating.
OP says "I have 2 pressurized canisters, both are 60 litres in size. Both are filled with 120 litres of ideal gas. "
then the process of heating starts.
and sorry i didnt understand this line, the first time "Canister B will obviously expand more than Canister A. " i thought that he meant the expansion of gas in higher temp container would be more.
and i don't think that canister expansion ll have much effect.
for example, if aluminium canister is used, thermal CoE for which is
0.000023 per K, volume change for 2000K is 0.138cubic units
 
ank_gl said:
i was talking about the state of the containers before heating.
OP says "I have 2 pressurized canisters, both are 60 litres in size. Both are filled with 120 litres of ideal gas. "
then the process of heating starts.
and sorry i didnt understand this line, the first time "Canister B will obviously expand more than Canister A. " i thought that he meant the expansion of gas in higher temp container would be more.
and i don't think that canister expansion ll have much effect.
for example, if aluminium canister is used, thermal CoE for which is
0.000023 per K, volume change for 2000K is 0.138cubic units
Ahhhh...I see what you mean.

I don't think that the OP meant to consider physical expansion of the canisters but we don't know that right now. The question isn't very specific. I am assuming the only expansion involved is what the gas is trying to do due to the temperature.
 
Ahh, sorry guys, i was not specific enough. In the OP i did not mean that we should consider the expansion of the actual containers, but the expansion of the gas. The first response by Russ was the most accurate and what I was looking for. I will have another question regarding expanding gases soon, so look out for this post. Thanks for all the replies.
Cheers.
 
spkr:
which canister will empty first?

What does empty mean ?

It means whith less pressure ( 1 ) or whith less mass of gas ( 2 ) ?

In case 1, note that for the canister whith high pressure it will take a time to reach the conditions of the canister whith less pressure and then they will be at same pressure. So canister A ( 100 ºC ) will empty first.
 
well i didnt get which condition are you referring to alvaros. gas ll be pushed outward because of the pressure differential. canister B has a higher pressure differential.
apply bernoulli, velocity of rushing gas is directly proportional to pressure differential. both cans have same amount of gas so B ll empty first
 
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ank_gl said:
well i didnt get which condition are you referring to alvaros. gas ll be pushed outward because of the pressure differential. canister B has a higher pressure differential.
apply bernoulli, velocity of rushing gas is directly proportional to pressure differential. both cans have same amount of gas so B ll empty first

The condition is pressure.

Suppose canister A is at 2Kg/cm2 and B at 10 Kg/cm2.
Yoou open the valves and, after a while, canister B will have 2 Kg/cm2, but then canister A will have less than 2 Gg/cm2, canister A will always be ahead.
 
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