Propane problem "pressure"

[Optimistic Paranoid]

i also heard that when getting a refill, the propane agent is supposed to flush the tank with nitrogen? first before refilling

I've heard of nitrogen purging being done by welders before they weld on or cut an old propane tank to use it for other purposes. Actually, you could use any inert gas, and argon is sometimes used instead of nitrogen, since welders have tanks of argon around for - it's either mig or tig welding, I forget which.

I have also heard that if a propane tank needs to be shipped somewhere, it needs a nitrogen purge first, as they CANNOT ship it if it has even a trace of propane in it.

When you buy a NEW tank, it usually has air in it, which also needs to be purged. The propane supplier can do this by either using a vacuum pump to pull all the air out, or by doing a series of fill and releases with propane. By the time you do this four or five times, there are only traces of air left in the tank. Note that SOME new tanks come pre-purged by the manufacturer, obviously by the vacuum method because, as we've seen, they can't ship them if they have any propane in them.

But no, a re-fill place would never purge the remaining propane out before refilling it. There would be no purpose in doing so.

 

[Optimistic Paranoid]

Sorry about the double post. Computer glitch.

BTW, not to be too pendantic about this, but we have a tendency to treat LPG and Propane as interchangeable synonyms. They're not. LPG is usually a mixture of Propane and Butane. From the Wikipedia article on the subject:

Varieties of LPG bought and sold include mixes that are mostly propane(C_3 H_8 ),mostly butane(C_4 H_10) and, most commonly, mixes including both propane and butane. In the northern hemisphere winter, the mixes contain more propane, while in summer, they contain more butane. In the United States, mainly two grades of LPG are sold: commercial propane and HD-5. These specifications are published by the Gas Processors Association (GPA)and the American Society of Testing and Materials (ASTM). Propane/butane blends are also listed in these specifications.

The problem is that Propane will convert from a liquid to a gas down to -40 degrees farenheit, but Butane stops doing so at 32 degrees farenheit . This has been reported to really screw up Canadian snowbirds who spend their winters in Mexico. Mexican LPG is very high in Butane. When they go back north with a full tank of Mexican LPG, they sometimes find their furnaces won't work in cold weather as the Butane just sits there in the tank and stays liquid.

There. Probably WAY more than you wanted to know on the subject.

 

[Old Crow]

i heard that the gunk/oil in the lines issue is another good reason to replace the regulator and rubber lines my question would be: how often? mine are brand new, as is my 20# horizontal tank . i also heard that when getting a refill, the propane agent is supposed to flush the tank with nitrogen? first before refilling

I've wondered about that 'when to replace' question for the regulator too. I believe this RV web page reflects the typical advice given to RVers.... replace the regulator (as preventive maintenance) every 10 to 15 years. This Propane 101 education website says the industry standard for regulator life is 15 years and some manufacturers claim theirs can go 25. And this Propane Education and Research Council study determined there's very little difference in failure rates between 15-year-old and 25-year-old regulators.

Beyond that, however, is this idea of oil/gunk in the regulator and lines.

I believe I'd only replace the regulator if I saw what I considered a significant volume of oil. If it malfunctioned, of course, there's no question. I'm just saying I'd probably replace a working one if I saw oil come out of the line. And I'd want to keep checking for oil for a while as that oil wasn't manufactured by the old regulator-- it was trapped there. There could be more in the tank to be trapped in the new regulator.

If the oil causes problems with the new regulator, then I'm not sure what the best approach would be. Perhaps call up a trusted propane tech and see if it makes sense to have the tank serviced (drained). I don't remember reading of anyone going that far.... I'm just trying to think what to do if you keep finding oil. If that new regulator's still functioning and you're just worried because you found some oil, maybe all you do is drain the oil out and put it back in service and check again later, assuming it will eventually stop showing oil.

The nitrogen question is also an interesting one. A search for 'nitrogen' in the Good Practices document I posted in post #12 tell us nitrogen is used to flush out large containers (ships and barges, rail-cars, and transport trucks) during shipment of liquid LPG.

I've not been able to find anything recommending nitrogen be used to flush a portable tank before refilling it. A new, never-filled tank must be flushed with propane vapors or evacuated with a vacuum pump as described here. That flushing procedure would also apply to any tank which has been drained and left open (exposed to air). But as far as I can tell, there's nothing about flushing a tank for a normal refill.

Also-- this RV Forum thread discusses how nitrogen is used to 'inert' a used propane tank for shipping.

Also- the rubber line-- I think I'd only replace an existing one is if it appears in any way questionable, i.e., cracked, worn, dried-out, etc. I'd also look for that hose vender like the one ntsqd mentions in his post above.

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