Propane Purging

[tomkay]

I recently replaced the service valve assembly on our propane tank.
I immediately put some propane into the tank from a 1LB cannister using an auxiliary fill hose.

I didn't have the tank purged before doing this.

Have I created a potentially dangerous situation to be concerned about?

Thanks.
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'87 Westy

[Timwhy]

Wouldn't the gas from a 1# tank just equalize the two tanks? I think you can just go get it filled up and the
person doing the filling can then purge it. I too just recently changed my fill valve and the bleeder valve.
The kid doing the filling purged the tank when I brought it to them detached from the Westy. The van
is parked for the winter and I didn't want to drive it over to get it filled up.

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[tomkay]

I'm not sure about the 1# tank equalizing pressure.

I was reading about it last night and came across many scenarios ranging from inability to fill the tank due to oxygen in the tank, introducing rust to the inside of the tank, reduced BTU potential due to diluted LP as well as inability to smell a leak because of the diluted LP. Also mentioned was the regulator freezing because of the oxygen(moisture) in the tank. That makes me a little nervous as we head to the snow for a couple of nights tomorrow.
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'87 Westy

[davevickery]

The not filling part is probably not true. I've filled tanks that weren't purged.

What I've read is supposedly the air somehow can cause higher pressures inside the tank. A potential rust is what I was told by a propane repair place, but with the thick westy tank, I don't think they woudl ever rust from the inside out. I don't know if there are other issues that rust could cause like dust getting into the regulator or something. He told me not to worry about it once I had filled it. I also read the smell of a leak could be partially lost on the first tank, but I doubt it and don't think that is a big risk anyway. You could open the relief valve and see if it is ordorless, I highly doubt it.

The moisture running through the regulator might be the biggest risk if there is enough to freeze inside the regulator.

But filling from a 1 lb bottle I don't think you put any liquid in the tank. If the little bottle wasn't tipped upside down while filling, you definitely don't have any liquid in the tank, just air and LP gas. They purge them with LP gas not liquid, so at this point you could still have it purged. They fill/purge the tank 4 or 5 times with gas to get the air mixture down to 5% or something, with the percentage dropping with each cycle. It doesn't take much gas to fill the airspace in the tank, so doing that 4/5 times doesn't use much propane and doesn't take that long.

[MsTaboo]

http://home.earthlink.net/~derekgore/rvroadiervfulltimingwhatisitreallylike/id45.html
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[tomkay]

I got the tank filled tonight and they were able to put in 2.8 gallons.

They said they couldn't purge it b/c it had some propane in it. The guy also told me that being I had put propane in it before having it purged that it could never ever be purged from here on out.
So. That was that.

I'll just hope that there isn't enough moisture in there to freeze the regulator and have it purged when it runs out next time?
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'87 Westy

[JPrato]

I watched the propane guys do a new tank install at my rental property. They dumped in some isopropyl alcohol into the tanks before they hooked them up and filled them with propane. When asked, the guy said that takes care of any moisture that might be in the tank. In proportion to the sizes of the two tanks, I would say an once of alcohol into a Westy tank would do it.
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Joe

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