[HWY36]

If my LPG tank is sitting at room temp, is everything in the tank gas? If it's in it's liquid form, why isn't the tank frozen?

[Gray Wolf]

Its under enough pressure to suppress the boiling.

[AgentPothead]

Because much like David Bowie, it's under pressure.
I swear GrayWolf's post wasn't there when I made mine. Looking at the timestamps we jinxed and I now owe him a Coca Cola.

[HWY36]

So, if the room temp is 80F, is the gas/liguid pretty much at 80F?

[AgentPothead]

It's been like 20 years, but since the vapor point of lpg is around -44, I'm going to wager that no, the lpg is not at ambient temperature.

[MrBungle]

its a mixture of liquid and gas, and yes it is room temp....the higher the temp of the mixture the higher the pressure inside the vessel and vice versa.... its all relative

[learningta]

Originally Posted by AgentPothead

It's been like 20 years, but since the vapor point of lpg is around -44, I'm going to wager that no, the lpg is not at ambient temperature.

In a room-temperature tank where it's compressed, it will be at room temperature. If you opened the valve so that it could expand/boil off it would drop the temp drastically, this is why you see regulators get condensation and even ice (depending on flow) on LPG-fueled applications like forges and foundry furnaces.

But without a phase/pressure/temp change it will eventually reach the same temperature as everything that surrounds it

[AgentPothead]

Originally Posted by learningta

In a room-temperature tank where it's compressed, it will be at room temperature. If you opened the valve so that it could expand/boil off it would drop the temp drastically, this is why you see regulators get condensation and even ice (depending on flow) on LPG-fueled applications like forges and foundry furnaces.

But without a phase/pressure/temp change it will eventually reach the same temperature as everything that surrounds it

Cool man thanks for explaining it!

[HWY36]

Originally Posted by learningta

In a room-temperature tank where it's compressed, it will be at room temperature. If you opened the valve so that it could expand/boil off it would drop the temp drastically, this is why you see regulators get condensation and even ice (depending on flow) on LPG-fueled applications like forges and foundry furnaces.

But without a phase/pressure/temp change it will eventually reach the same temperature as everything that surrounds it

So if I filled a 4ft, 4' diameter column with 10lbs of LPG (which is about all it will take) and sealed it off, will that 10 lbs of mostly liquid remain liquid when it eventually warms up to it's surrounding room temp because it's compressed?

[learningta]

Originally Posted by HWY36

So if I filled a 4ft, 4' diameter column with 10lbs of LPG (which is about all it will take) and sealed it off, will that 10 lbs of mostly liquid remain liquid when it eventually warms up to it's surrounding room temp because it's compressed?

It really depends on the pressure it's compressed to at ambient temperatures.

I'm assuming you meant to say 4'x4" column, because a 4' tall 4' diameter column can hold quite a bit more than 10 lbs of LPG

Assuming it all started as a liquid, it would boil off some of that liquid into gas form as the temp rises towards ambient, until equilibrium is reached between the liquid form and gas form. This is what vapor pressure refers to:
https://en.wikipedia.org/wiki/Vapor_pressure

Given enough space to expand and low enough pressure of a given chemical with a below-ambient boiling point, all of it will eventually boil off towards gas. Whether that will happen in your instance or not will likely require more data.