I highly recommend that you get the pressure relief valve on your motorhome's propane tank replaced. This is a very important part of the safety systems on your RV. When you get your RV filled up with liquid propane, it is never filled up to a 100%. The tank is actually filled up to 80% capacity. The reason is that liquid propane expands with heat. Filling the tank up to only 80% capacity allows for expansion of the liquid propane.
Let's say you got your propane tank filled up on a very cold day and then a couple of days later you decide to take a trip to a hotter climate. Being in a hotter climate causes the propane to expand. In some cases the propane expands so much that it could exceed the pressure rating of your RV's propane tank. Before the pressure gets above the tanks pressure rating the relief valve automatically opens up and vents the excess propane.
If the pressure relief valve is not working; the pressure in the tank could get high enough to exceed the tanks rating and rupture the tank releasing all of the propane at one time. If the propane gets close to an open flame the gasses will explode with great force. That is why a propane dealer will not fill up a propane tank with defective relief valve.
Yes, you could use a portable BBQ propane canister, but that would require a modification to the propane lines leading to your RV's propane regulator. This modification if not done properly can cause a serious fire hazard and possibly cost more than getting your pressure relief valve replaced.
I cannot tell you how much getting the pressure relief valve replaced will cost. But, I can tell you that it will cost you a lot less money than having to replace your RV because it caught fire due to a bad pressure relief valve on your propane tank.
None of this is meant to scare you I am just trying to emphasize the fact that you need to take your RV to an RV repair shop and have the propane tank fixed by a certified RV Technician. You may be surprised that it will not cost as much as you think it might but, it must be done and it must be done right.
Everything-About-RVing.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com.