As a Plant Engineer, I learned, the hard way, that fuel suppliers often ship a MIX of liquified butane and propane, selling it as "propane", because butane is sometimes less costly.

 

Overnight temperature plummeted, the plant's boilers shut down, and I found the "propane" had frozen enroute to the building from two 30,000 gallon tanks.

 

The supplier had missed the weather forecast, failed to ship the non-mix (propane only), and we were stuck.

 

Butane "freezes" at a higher temperature than does propane.

 

I wonder if others have encountered such fun? imp

Hmmm... sounds like Butane would be a reasonable candidate for clathrate experiments

I am assuming that reducing the pressure was not an option?

 

(At atmospheric pressures, butane melts at -138.4 deg C).

propane/butane is almost never stored at standard pressure. that would be innefficient and expensive.

How cold is it?

The effect of pressure on freezing point isn't usually very big (because the change in volume isn't very big).

In addition, frozen butane would be reasonably soluble in liquid propane, so the freezing point of the mixture would be lower than that for pure butane.

 

I think you have water in the line and it has frozen to ordinary ice.

How cold is it?

The effect of pressure on freezing point isn't usually very big (because the change in volume isn't very big).

In addition, frozen butane would be reasonably soluble in liquid propane, so the freezing point of the mixture would be lower than that for pure butane.

 

I think you have water in the line and it has frozen to ordinary ice.

 

One MIGHT reasonably wonder how much water is shipped along with the fuel by the supplier! Since there is no air in the storage tank (only fuel-gas vapor above liquified fuel), condensation of water out of contained air is not a problem, as it is so often in fuel oil storage tanks which contain air above the oil, often at atmospheric pressure. imp

There shouldn't be much water in the fuel because it's not very soluble in LPG. On the other hand I don't think you would need much to foul up a pipe.

Anyway, unless you are below -138.4C it's not butane. IIRC you need about 20 carbons in a chain before it's solid at room temp even decane would need a very cold day.

Something like benzene or cyclohexane might explain it, but 2/3 of the earth's surface isn't covered with benzene. My guess is still water.