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From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Propane leak
Date: Mon, 27 Mar 2006 18:41:04 -0500
Message-ID: <d7tg22hbg7aoopd19cplm2jgq699um9ap9@4ax.com>

On 27 Mar 2006 22:50:53 +0100, "Jon Porter" <jporter@netwalk.com>
wrote:

>While doing my spring shake down and inspection today, I discovered a
>propane leak (smelled it). It's the supply valve on the vehicle mounted
>Manchester tank, I can actually feel it spray out while turning the valve.
>Is this something that can be replaced by an individual, or should it go to
>a pro? The curve here is that the tank is completely full. If I have to take
>it to somebody at this time of year, I expect that there's be a long wait
>(weeks) before I get it back, so I would rather do it myself.

Sure, no problem replacing the valve.  The only sticky part is that
the thread dope may be hard as a rock which will require a little
heating to break loose.  I use a propane torch but if that makes you
nervous, a heat gun will do.

Here's a little trick for loosening the valve.  It's hard to get a
wrench grip on the valve unless you have a special valve wrench.  Get
an old POL fitting (or even a new one if you have to).  Using a
reducer, attach several feet of 1/2" iron pipe to the fitting.  Screw
this fitting into the valve and use the iron pipe as the lever to
unscrew it.  If the valve is REAL tight, find a steel rod, preferably
drill rod, that will fit inside the passageway in the brass fitting.
Use a piece a foot or so long.  Stick it inside the brass fitting to
strengthen it.  If the fitting still bends, the steel rod will contact
the inside of the iron pipe and add much strength.

There is a special tool made for this purpose that consists of a steel
rod with a POL type left-hand thread on the end.  I've always been
able to break a valve free just using the improvised steel-reinforced
brass fitting.

Use this technique only on a valve that is to be discarded, for the
POL socket is almost always stretched out of round.

About being full.  That's not a problem - go ahead and use up the
propane before replacing the valve.  A propane tank valve (at least
every one I've ever seen) has a back-seat.  That is, a second valve
that seats when the valve is fully opened.  This back-seat seals off
the valve stem so that the stem seal does not have to withstand the
pressure.  Basically, the stem seal is only for when the valve is in
transit from open to closed or vice versa.

Try turning the valve fully open and gently tightening it against the
resistance.  Unless the back-seat is boogered up, this should stop the
gas leak.  Then take a small wrench and try tightening the packing nut
(what the stem sticks through.)  This should stop the leakage for
good.  If not, you can always replace the valve.

John


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Propane leak
Date: Wed, 29 Mar 2006 23:28:56 -0500
Message-ID: <hvmm22dg401g2ug9cu5ov3v8juesd3868l@4ax.com>

There is no requirement for "ICC" (permanently mounted) tanks to have
OPD valves.  Some do, some don't.  Neither of our two MH's nor the
tank for my concession stand have them.  Any fill monkey who relies on
one is incompetent and dangerous.

Moreover, the government-mandated OPD valves are not reliable.  I've
been accumulating evidence for some time.  I bought a valve to take
apart to figure out how to defeat the damned thing. (easy, just
unscrew it from the main valve.)  I noticed that the OPD valve itself
did not seal very tightly.

About that same time someone read one of my propane articles and wrote
me about a problem.  His grill regulator was icing up and spitting
liquid propane.  After I confirmed that he had the tank upright, it
became evident that it was grossly overfilled.  I had him open the 20%
valve and sure enough, out came a steady stream of liquid propane.  I
had him let the tank bleed down until the 20% valve cleared and all
was fine.

I made a post about that probably a year ago.  Since then I've gotten
over a dozen emails from readers who've experienced the same thing -
received an over-filled 20 lb tank from a C-store rack.

Apparently the bulk tank outfits like Blue Rhino are attaching a
multitude of tanks to a filling manifold and are relying on the OPD to
shut off the propane flow.  It ain't working!

The valve I dissected shuts off enough to make the pump change sounds
so if the guy is standing there and paying attention, it's (sorta) OK.
But if he hooks up a bunch of tanks, flips on the pump and walks away
or just daydreams, not OK.  The correct way to fill the tank is by
weight.  I'm seeing fewer and fewer fill stations equipped with
scales.

This is another example of the Rule of Unintended Consequences making
government meddling not quite work as intended.  The situation now,
post-OPD, is worse than it ever was before, IMO.

John




From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Changing my own propane valves
Date: Fri, 05 Oct 2001 15:52:50 -0400

The propane dealer will usually have a large round clamp that holds
the cylinder and a special wrench that looks somewhat like a sink
wrench to remove the valve.  Convenient but not necessary.  Getting
the old valve out is the hard part.  If the valve is sealed with
teflon tape, it will usually come out with enough force.  If pipe
dope has been used, usually a little heat around the tank bung will
be necessary.  In any event a little heat will make either type of
seal come loose easier.

At home I stick a large hunk of water pipe through the top ring to
hold the tank still and use a large crow's foot wrench and a 1/2"
ratchet with extension to turn the valve.  The crow's foot can be a
bit destructive to the valve but since you're not trying to save the
old valve, that isn't a problem.

For the new valve I use gas grade (usually yellow) teflon tank if I
plan on using the tank immediately.  If I can wait awhile for the
stuff to cure, I use Loctite pipe thread sealer.  This anaerobic
cyanoacrylic-based pipe dope polymerizes in the absence of air
(inside the threads) and will seal even poorly formed or damaged
threads.  The advantage for propane valves is that it will seal even
with the valve not screwed in as tightly as possible.  It always
seems like the "right" amount of tightening leaves the valve opening
pointing toward the ring!  With teflon tape you have to force
tighten the valve the partial turn it takes to get the outlet
pointing correctly.  With the loctite, you can simply stop
tightening when the valve points right even  if it doesn't feel
optimally tight.  Do NOT back up!  The dope starts curing
immediately when the tightening stops so if you back up, you'll
cause crumbles of the stuff to come out of the threads.  That would
contaminate the propane and could leak.

I don't like conventional pipe dope.  With the hardening type, the
stuff sets up so hard that removal is very difficult. With the
non-hardening type, unless the valve is forced VERY tight, the joint
stays a bit loose and can turn if you have stress on the regulator
or pigtail.

While you have the valve out, shine a flashlight down in the tank
and make sure there is no rust in there.  Anything more significant
than pinpoint spots means the tank must be condemned or refurbed
according to the CGA inspection standard.  Also be sure and shake
out any debris that fell down in the tank as the old valve was
removed.

If you can get some, it is a good idea to put about a cup of dry
methanol in the tank as a drying agent before inserting the new
valve.  This is recommended by CGA.  On the first fill make sure the
guy opens the 80% valve from the start of the fill to let any
trapped air purge.

John




From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: OPD valve failure
Date: Tue, 22 Jan 2008 17:36:27 -0500
Message-ID: <clrcp3d7fejapvcchvgqsfv2mva2gm3qcj@4ax.com>

On Tue, 22 Jan 2008 14:52:45 -0600, Bob Giddings <bobg@escapees.com> wrote:


>So it's a trailer problem.  The surprise to me was the OPD valve
>didn't shut off as I expected.  A small leak could just go on
>until the tank was empty.  Not only dangerous but expensive.
>
>Anyhow it's a cheap fix.  You just have to do it.

OPD doesn't have a leak-stop function.  It is excess-flow limited (to 175,000 BTU/hr
if I recall correctly) and seals shut when you remove the hose but it can't detect a
slow leak.  Or any leak, for that matter.  The leak looks just like consumption from
the valve's location.

Unfortunately OPD is another one of those government do-good things that is going bad
wrong.  I've tested a number of valves and NONE of the over-fill valves shut off
sufficiently to stop over-filling the tank.  As you're learning, the rubber inserts
that replaced reliable brass-on-brass seals on the old valves, age and deteriorate.
My cynical side might think that government and industry worked hard to get a
defined-life product in the stream of commerce to replace the old last-forever
valves.

John


 



































































































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