LPG pressure relief?

[JJZ 109]

Yesterday I had 3 100 pound LP gas cylinders refilled. Brought them home and attached the lines to 2 of them. 1 to the kitchen stove and another to the furnace. The third is spare.
Today, wife and I could smell LP and hear hissing. The 2 tanks attached to lines appeared OK. The spare tank had fuel leaching out of it. The valve was cranked shut as well as the bleed valve. I cracked it open for a second and then closed it right back up. All seemed well. 20 minutes later the same thing happened again. There appears to be a pressure relief valve of some sort directly opposite of where the line would screw into the shut off valve. That's where the visible gas and hissing were coming from.
When the kid at the local hardware filled the tank, I could hear the pump sound like it couldn't put any more into the tank and the meter stopped ticking it off while the kid yakked on. The afternoon sun was beating on the tank at the time of the incident. Is it possible that the tank was overfilled and that the sun had expanded the gas enough to activate a pressure relief? Never saw this happen in several years of using liquid propane.

 

[Egon]

Yes

 

[k0ua]

I believe that is exactly what happened. The are supposed to be filled to 80 percent. I have seen propane guys fill them a bit more in the winter, but not in the summer..

Propane Cylinders - Important Pressure Relief Valve Information - Safety Engineering Network (SAFTENG)

 

[JJZ 109]

Thanks for the replies. I almost said something to the kid, but didn't want to tell him how to do his job when I wasn't exactly sure myself. Like I said, the meter stopped clicking it off and the tank obviously (to me anyway) was not taking on anymore gas.
Thanks k0ua, the symptoms described in your link are just what happened.

 

[orezok]

You can check by carefully while wearing gloves and eye protection opening the screwdriver vent on the side of the valve. If it spits "liquid" LPG, it's overfilled. You can bleed it off until only gas comes out at 80% full.

100# tanks don't have the OPD valve the kid is used to and can be overfilled.

 

[JJZ 109]

You can check by carefully while wearing gloves and eye protection opening the screwdriver vent on the side of the valve. If it spits "liquid" LPG, it's overfilled. You can bleed it off until only gas comes out at 80% full.

100# tanks don't have the OPD valve the kid is used to and can be overfilled.

Thanks. Its got a little thumb wheel vent on the side of the valve that he had cracked while filling. I can bleed some off with that.

 

[oldnslo]

Why don't you just connect the overfull tank to your stove and use the gas Vs expelling it into the atmosphere?

 

[JJZ 109]

Why don't you just connect the overfull tank to your stove and use the gas Vs expelling it into the atmosphere?

There's never a guarantee that mama will be firing up the stove at any given time. :crystalball: It's electronic with no pilot light so I don't think it would help the situation unless we were planning to use the stove right off.
I bled some off this morning before the sun got around to that side of the house, but not really an excessive amount. As the day went on and it warmed up I had no pressure relief valve action today.