Large propane tank +small demand =regulator freeze?

Solid_Fuel_Man

I was talking to a local propane supplier about some troubleshooting. He said last winter he had a couple of accounts with 500+ gallon tanks with small demands which had experienced first stage regulator freeze-ups. He said with the same L.P. supply, they didn't have the same freezing issues with his larger usage accounts.

We were having this discussion because I was proposing the same scenario with my own home. He said the tanks were properly purged and methinal added at that time.

Any ideas? We thought that due to the low draw and large wetted surface od the tank the methinal was not vaporizing with the L.P. and allowing the water to freeze in the regulator? He said he changed the first stage regulator which got things back up and running. Also the frozen regulators all had water coming out of them when they thawed out in the shop....

hot_rod

Here is some good info on LP and water content. Sounds like water in the tank and possibly some water in the LP they deliver.

http://www.propanecouncil.org/uploadedFiles/REP_11992 Methanol to Control Water Freezing Report.pdf

EBEBRATT-Ed

you answered your own question. water in the tank that isn't supposed to be their

I don't believe usage is a factor. If anything higher usage would be more likely to cause freezing

Solid_Fuel_Man

That's what would seem to be the case. However he said he hadn't had any other regulator freezing problems. Only in two accounts with large tanks and small draws. That's what seemed so contradictory.

JUGHNE

So those 2 accounts could have old LP that was wet. Everyone else has freshened up their tanks and diluted the water, or burned it off in mild weather when freezing would not have been a concern.
Just a WAG.

Henry

We have tables for the amount of surface needed to evaporate at low temperatures. The surface area has to increase for higher consumption. It is very common to have very large storage tanks for use with generators. But a heating load or stove has no effect on these large tanks.- in sub zero weather. It is definitely a water problem.

Gilmorrie

As Henry stated, when propane evaporates, the remaining liquid is reduced in temperature, and the pressure of the propane drops. Large users often have fired evaporators to maintain the pressure during winter weather.

Solid_Fuel_Man

Thanks all, this completely confirmed all that makes sense. This supplier (local 4 man show) was just telling me about this anomaly and we were discussing possible causes.

None of these had vaporizors. Just wetted surface evaporation.

I am all set for my own 500gal horizontal tank. By my calcs it has the potential to last 5 years. If I only use L.P. for occasional heat, as my current range and dryer use 50gal per year.