propane tank and hot water heater

While this isn't a common problem, I have found it several times over the years in tanks that have been in service for many years. Twenty years isn't a long time, but 25 gallons isn't a big tank either.

The tank gathers non-flammable liquids in the bottom of the tank which are from lower quality propane which has significant amounts of heavy ends, oils and other liquids not removed in processing. Generally called commercial grade, not HD-5. This is never removed from the tank since it doesn't vaporize or burn and eventually reduces the liquid capacity of the tank.

Evacuation of this residual liquid is easy if the tank has a bottom plug. If not removal and inversion is required. Either way it is a stinky and dirty job that I wouldn't wish on my worst enemy.

MOST Asme tanks will spew LIQUID at the 80 percent valve when full. It would be interesting to see if that happens when the tank is full. IF NOT, then the Auto fill is defective and the float is probably bent inside the tank shutting the LP fill OFF too early. I would drain the tank completely and then refill after all vapor and liquid has been purged. Doug

25*.8 = 20 gallons That's the most it can take.

Tank may have something in it other than propane.. Visit a PROPANE WHolesale place that does tank recertifications and talk to them.. YOu may wish to have them service your tank.

Thank you so much for the input.
B

Something REALLY strange going on....

Archived brochure for 1997 Tour Master ((Gulf Stream Class A) lists ALL models having 150# LP tanks.
Propane weighs 4.2#/gallon......that comes out to 35.7 gallons :H

Now IF that 150# is Total Capacity then 80% Liquid Level (FULL) would be 28.5 gallons.

Propane should continue to flow until tank is empty.
Liquid turns to vapor....vapor comes out of service valve....LP Reg maintains 11"WC (0.4 psi) on system until NO Vapor

Propane Tank Components (left to right)
Magnetic roller float....liquid level gage
Relief valve stand tube....in vapor zone
Fill Valve float......stops filling at 80% liquid level
Bleeder Valve stand tube...set at 80% liquid level
Service Valve stand tube...in vapor zone




Gulf Stream Archival


1997 Tour Master Brochure



Possible issues......... (like 'rctour' suggested)
Fill valve float set at 15 gallons vs 25+ gallons and stops filling then tank goes empty when 15 gallons is used....no more vapor (nothing to prevent vapor flow thru service valve except EMPTY tank)

You have an interesting question and I'm not an expert in propane tanks but I do know they have a float device inside controlling the amount of propane that is inserted like a toilet bowl. Perhaps the float is stuck given yours is 20 years old?

Gage is correct

Yes. It's only taking 14 gallons.

donn0128 wrote:
How do you know for sure it is down to 10 gallons? When you fill it is it only taking 15 gallons?

Exactly^^^^^

Tank gauge reading incorrectly :H

How do you know for sure it is down to 10 gallons? When you fill it is it only taking 15 gallons?