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Can and Does Propane Freeze? Does LPG Gas Freeze - LPG-Propane Freezing Point

LPG-propane does not freeze in winter. Only under laboratory conditions could you make LPG-propane freeze, at -188 °C (-306.4°F).

LPG-propane BOILS at -42°C (-43.6°F), which means that liquid propane does not vaporise - turn to gas - below that temperature. So, unless you live in Antarctica, you should have no problem.

So, yes, technically LPG-propane (LPG) can freeze but it never freezes outside of a laboratory situation.

Then how does frost and Ice appear on propane tanks (LPG cylinders), regulators and fittings? 

Why Does LPG (propane) Gas Freeze?  LPG-Propane Freezing Point

Propane (LPG) freezes at a very low temperatureNo, LPG gas does not freeze in any non-laboratory situation, as the LPG (propane) freezing point is at -306.4°F (-188 °C). So, you might be able to get it to the LPG (propane) freezing point in a laboratory, but not in real life.

However, what many really want to know is if the LPG-propane tank ever gets too cold to work.

The average winter temperature at the South Pole is about -56.2°F (-49°C).

So, if you live in Antarctica, your LPG (propane) could stop functioning if the temperature dropped below -43.6°F (-42°C), the boiling point of LPG (propane).

The boiling point is the temperature at which vaporisation begins and the liquid LPG (propane) turns to gas.

For the rest of us, the propane will keep working.

However, if you have a smallish tank, really cold weather and high demand, your propane tank might struggle to keep up.

If you live in a snowy climate, it’s a good idea to keep the snow from accumulating on top of exposed propane tanks, so that the sun can help warm them.

Does LPG Freeze in Winter

No, LPG does not freeze in the winter. And if you get propane, and you don't live in Antarctica, it should work fine. However, if you get butane and the temperature drops below freezing, the butane will stop vaporising.

Do Propane Tanks Work in Cold Weather?

Yes, LPG-propane tanks work in cold weather but not quite as well. As you can see from this vaporisation table, the gas output, measured in MJ/hr, drops off as the temperature drops.

LPG-Propane Vaporisation at Various Temperatures

Maximum vapourisation rates at different ambient temperatures

Size -18°C

-7°C

-1°C 4°C 10°C 16°C
45kg 47MJ/hr 70MJ/hr 84MJ/hr 90MJ/hr 101MJ/hr

113MJ/hr

What about Butane? Does LPG-Butane Freeze?

Does butane keep working in cold weather? NO, not very well. Butane stops vaporising – turning to gas – at -0.4°C (31.3°F). However, with the very low LPG-Butane freezing point of -140°C (-220°F), liquid butane would also not freeze outside of a laboratory environment.

So, it would not be rare to have no butane gas in a winter climate that doesn’t even come close to Antarctic low temperatures.

It just needs to be below freezing.

That's why propane is preferred in colder climates, as it keeps working… with the possible exception of the South Pole!

How Does Ice Form on Propane Tanks (LPG Cylinders)? Propane Tank Frost

Frost line a a propane tank - gas bottleTo form propane tank frost or ice on the outside of a propane tank, the surface temperature of the tank only needs to drop below 32°F (0°C). The liquid propane itself does not have to reach the LPG (propane) freezing point, which occurs at -306.4°F (-188 °C).

The liquid propane inside the propane tank can remain a liquid, without freezing, even whilst chilling the propane tank itself to well below 32°F (0°C).

The propane tank gets colder when you are actually using the gas, resulting in condensation, frost or ice forming on the propane tank, when sufficient humidity is present.

Initially, condensation forms when the temperature of the propane tank drops below the dew point.

This is exactly the same as the condensation you get on a humid day with a glass of ice water.

As the temperature continues to drop, the condensation may turn to frost or ice.

Why Does the Propane Tank (LPG Gas Bottle) Get So Cold?

A propane tank get cold in the first place as the result of a process called vaporisation, during which liquid propane turns to gas. This happens at the very low temperature of -43.6°F (-42°C), but well above the liquid propane-LPG freezing point of -306.4°F (-188 °C).

Propane (LPG) is stored under pressure, as a liquid, in a propane tank and is also referred to as natural gas liquids – NGL.

It turns back into a gas by 'boiling' into gas vapour.

To boil, the liquid propane draws heat from the steel walls of the propane tank. 

This, in turn, makes the tank feel colder than the ambient temperature.  

The propane tank gets even colder when you are actually using the gas. 

With sufficient humidity and when you are using gas rapidly, condensation or ice can form on the propane tank. 

The visible condensation or frost line indicates the level of the liquid gas remaining in the tank. 

Ice on gas cylinder - propane tanke

The picture above shows this on a small dark coloured gas bottle, so it is easier to see.

LPG-Propane Gas Regulator Freezing

As the propane (LPG) passes through the LPG-propane gas regulator, it expands, resulting in very cold gas vapour temperatures and external propane regulator freezing. This is caused extremely cold temperatures and as the propane regulator reaches freezing, with sufficient humidity, ice will form on the outside of the regulator.

This is why, under normal operation in warm and humid climates, the outside of a propane gas regulator will feel cold to the touch and may also be wet, frosted or frozen.

Final Thoughts

People ask “Can and does propane freeze?” but it probably isn’t really the question that most people want answered.

The literal answer is that propane (LPG) can freeze but that it would never happen in normal use.

What they typically want to know is if the ice that forms on the outside of propane tanks (LPG gas bottles) and regulators will stop the gas flow.

The formation of frost and ice can and does happen without impeding the flow of gas and without the liquid propane (LPG) freezing.

However, the formation of frost or ice is indicative of a vessel being too small to meet the vaporisation requirements of the system.

The use of a larger vessel and/or a vaporiser may be indicated.

 

 

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The information in this article is derived from various sources and is believed to be correct at the time of publication. However, the information may not be error free and may not be applicable in all circumstances.