I got under my RV (2006 Gulfstream BTCruiser) to clean and repaint some rusted spots on my propane tank. While on my back looking up at it I noticed a plastic plug covering a threaded connection.Anyone know what that is for? Could it be to attach a propane hose to in order to fuel something like a gas grill?I also noticed that my gas tank has lost some of it's black paint and where it has it looks to be rusted or corroded. Yet the tank looks like it is galvanized or something like it. Should I clean and repaint it or leave it alone?Thanks for any help with my questions.

The gas tank on our ford is all stainless construction. The outside looks cruddy, but hey, that's a dirty environment under there.I'd leave it alone.Regarding the port on the propane tank... I have no idea.

If this unit had a previous owner it could be a port for an Extended-Stay. Or depending where it is installed in reference to the regulator it could be a low pressure port for a gas grill etc. But I'd bet on an extended-stay.http://www.amazon.com/Marshall-Gas-Controls-536-00-Extend-A-Stay/dp/B002UC4T6C

BruceMc - I did not think it would be a metal that would rust. Mine must be stainless as well. Thanks.

bobsallyh - I am the original owner so whatever is there came with the tank as installed. It taps right into the tank and not the regulator. I am aware of the Extend-A-Stay item, however I had no idea it could be threaded right into the tank. Thought I had to get a new regulator that would accept it. Thank You.

Where on the vessel is the threaded port located?

Propane Tank Question & Gas Tank Question | Good Sam Community

14 Replies

Old-Biscuit
Explorer III
Jul 11, 2015
MEXICOWANDERER wrote:
Confused. A relief valve meaning liquid immersed overpressure protection device that vents to the vapor section of the tank? I misunderstand the point.

Propane tanks---propane cylinders have safety relief valves that open on high pressure (they vent vapor----NOT liquid) to atmosphere
Never should be 'immersed' in liquid.

The relief valve in question on this MH propane tank is bottom mounted with a internal tube that goes thru the liquid into top of tank where vapor is.
MEXICOWANDERER
Explorer
Jul 11, 2015
Confused. A relief valve meaning liquid immersed overpressure protection device that vents to the vapor section of the tank? I misunderstand the point.
pkunk
Explorer
Jul 11, 2015
I stand corrected....
Old-Biscuit
Explorer III
Jul 11, 2015
pkunk wrote:
If it's on the very bottom of the tank it is not the relief valve. The relief valve is above liquid level and will blow vapor if the pressure gets too high. The pic above is looking at a service tank from above, not a MH tank from the side. Tanks have a drain plug on the bottom that is used only when the tank has no gas in it to drain the residual oil that accumulates over the years.

Actually it is a Safety Relief Valve.

When tank is made/used for RVs the relief valve is installed at bottom with a tube that goes to top of tank area (Vapor).

If relief valve was installed on top o\of tank like a skid mounted/residential tank then should relief valve open it would exhaust vapor inside an RV. Not a good idea.

Look at diagram posted.
That is an RV tank. And view is from side.
pkunk
Explorer
Jul 11, 2015
If it's on the very bottom of the tank it is not the relief valve. The relief valve is above liquid level and will blow vapor if the pressure gets too high. The pic above is looking at a service tank from above, not a MH tank from the side. Tanks have a drain plug on the bottom that is used only when the tank has no gas in it to drain the residual oil that accumulates over the years.
Jpjlauer
Explorer
Jul 11, 2015
Chris - Relief Valve is what it is. Your diagram is exactly what I am seeing. I should have looked at Manchester Tank website first.
Thanks to all.
Chris_Bryant
Explorer II
Jul 11, 2015

Courtesy of Manchester Tank
Jpjlauer
Explorer
Jul 11, 2015
vic46 - the threaded port in on the bottom of the tank.

Old-Biscuit - given your reply it must be a "Safety Relief valve" because it is not in any way associated with the regulator. I'll make a guess and say it is threaded so that in some installation situations a tube can easily be screwed into the port to exhaust vapor away from the propane tank compartment.
Old-Biscuit
Explorer III
Jul 10, 2015
If it is under the protective shelf/cover where the rest of components are it is the 'Safety Relief Valve' (tube goes to top of tank in vapor area)

Valve is installed down low/under so should it open due to high pressure it is directed down and away from vehicle. Plastic cover is just a protective cover for road debris

Extended Stay----'T's etc. are installed after service valve and before regulator (for high pressure) or after regulator (for low pressure).

All additions are after service valve so that 1 valve secures everything (safety)
vic46
Explorer
Jul 10, 2015
Where on the vessel is the threaded port located?