From: John De Armond
Subject: Re: OVERFILLED LP TANK - Danger??
Date: Sat, 18 Dec 1999 18:27:02 EST
Newsgroups: rec.outdoors.rv-travel

Chuck Gell wrote:

> The last time my built-in 16 gallon LP tank was filled, it was filled so
> full that the gage is way above the "full" mark.  Normally it only gets
> filled to about the 3/4 mark.  I've tried bleeding the gas off but so far
> the needle hasen't moved, possibly indicating GROSS overfilling, way above
> the range of the level gage.  I went out today to run all the systems prior
> to our winter trip and noticed an LP odor around the tank, and I'm
> suspecting that the overfilled LP tank has put liquid LP thru the regulator
> and cracked the diaphragm.

The gauge may or may not mean anything.  The only really meaningful
test is to open the 20% valve and see if vapor or liquid comes out. 
If vapor comes out, you're fine and the gauge is simply out of
calibration.  If liquid comes out, rock the RV a little.  IF liquid
and vapor spurt alternately, you're still OK, as it has been only
slightly overfilled and there's plenty of safety margin.  If you get
only liquid and it's cold out, you need to get rid of some gas. 
Easiest way to drain it is to hook an hose with a POL fitting to the
tank, run the line to a safe place, aim it up in the air and let 'er
rip.  Though propane is heavier than air and will normally sink to
the ground, the high velocity gas directed up in the air will
entrain enough air not to settle and become explosive.  You should
be able to bleed enough gas to hit the 20% valve in a few minutes.  

John

From: John De Armond
Subject: Re: How to Fill LP Tanks --
Date: Sat, 18 Dec 1999 22:07:55 EST
Newsgroups: rec.outdoors.rv-travel

Chuck Gell wrote:
> 
> I posted  a note earlier about my overfilled LP tank.  This post is
> regarding what SHOULD have happened.
> 
> I think that my 16 gallon LP tank in my 1996 Sea Breeze motorhome has been
> overfilled (the gauge needle is way past "full" and was against the pin),
> and that my regulator has been damaged as a result (ran the systems today,
> 12/18/99, to prepare for the winter trip, and smelled LP gas in the tank
> compartment).  Maybe the overfilled tank is causing the pressure relief
> valve to lift and the regulator is okay, but I doubt this.  I've opened the
> vent valve and am getting a white stream of LP, some of which settles in
> droplets on the tank frame.  I believe that the stream should be clear vapor
> and not causing droplets.  I'll do a leak check in the next few days and
> replace the regulator if needed -- bought a new one today.  Would appreciate
> any comments on all this.

You are correct - you have been overfilled.  Your regulator probably
isn't damaged.  If the inlet pressure is high enough (from the tank
being solid with liquid and then expanding when warmed), the
regulating needle can be forced off its seat.  That will allow more
pressure into the distribution system than designed.  HOWEVER, the
regulator also has a safety relief diaphragm designed to protect the
system from just this occurrence.  It will lift at a pressure a
couple inches of water pressure above the regulating point.  This
vents to air (or your tank compartment).  That is likely what you're
smelling.

If the safety has/is lifting, it should be replaced.  When I went to
Propane Polytech in preparation to getting my propane dealer's
license, the instructor and the literature handed out strongly
advised this path.  Though the relief valve is a spring loaded
blowoff valve and not a rupture diaphragm, it is recommended to
treat it as a one-use device.  The reason is that after the valve
has sat under spring pressure for years, the sealing gasket has
taken a set and it is unlikely the valve plunger will re-seat the
same.  Weeping is the frequent result.  

> However, for future reference, what is the correct fill procedure?  I need
> to have a better understanding of this now that it's apparent that
> inexperienced persons are sometimes filling the LP tanks.  From what I
> understand, I believe that this should be the fill procedure:
> 
> 1.  Our action:  Shut off all LP appliances (refrigerator, furnace, stove,
> water heater).  Main engine off, and no other sources of flame or spark
> present.
> 2.  Attendant closes main LP valve.
> 3.  Attendant removes yellow fill cap, inserts fill hose, opens tank 80%
> vent, fills tank until clear vapor turns to white liquid, then shuts off
> fill line and vent.  Removes fill line and replaces yellow cap.
> 4.  Attendant SLOWLY opens main LP valve.
> 5.  We restore LP appliance operation as desired.

Correct.

> 
> If the tank is properly filled, the tank level gage needle should not be
> above the fill line corresponding to the ambient temperature, and will seem
> to be about 80% full.  

Again, correct, assuming the gauge is properly calibrated.

>If above this, the tank should be vented in a
> well-ventilated area with no possibility of flames or sparks within 15 feet,
> by opening the 80% vent valve for releases of about a half-minute, then
> close and observe gauge response.

That will work.  I prefer to have positive ventilation when I'm
opening the 20% valve, particularly if there is going to be some
liquid discharge.  I have a fan that produces a nice laminar flow
that I set up several feet away.  It directs a non turbulent stream
of air along the ground.  The air will stay moving close to the
ground for maybe 20 feet.  I arrange for the discharge of the 20%
valve to end up in this air stream.

I don't like letting a lot of liquid escape from the 20% valve for
the simple reason that much of the methyl mercaptan odorant will
stay behind.  Aside from getting on your hands and cloths, it can
hang around and be strong enough to fool you into thinking you have
a gas leak for several days.

John

> I wish that there was a website or technical manual that went into this
> level of detail but have not been able to find one.  Your help would be
> appreciated!!  Thanks,

Find out who your state dealer licensing agency is.  They have
plenty of materials available for free on the subject.  Here in Tn,
they call it the propane dealer's license study guide.

John

From: John De Armond
Subject: Re: How to Fill LP Tanks --
Date: Sat, 18 Dec 1999 23:29:56 EST
Newsgroups: rec.outdoors.rv-travel

Neon John wrote:
> 
> 
> You are correct - you have been overfilled.  Your regulator probably
> isn't damaged.  If the inlet pressure is high enough (from the tank
> being solid with liquid and then expanding when warmed), the
> regulating needle can be forced off its seat.  That will allow more
> pressure into the distribution system than designed.  HOWEVER, the
> regulator also has a safety relief diaphragm designed to protect the
> system from just this occurrence.  It will lift at a pressure a
> couple inches of water pressure above the regulating point.  This
> vents to air (or your tank compartment).  That is likely what you're
> smelling.
> 
> If the safety has/is lifting, it should be replaced.  

I reread this and realized the meaning was ambiguous.  By "safety",
I mean the relief valve on the tank and not the one in the
regulator.  Sorry about any confusion...

Well off to the mountains!  I love spring in December :-)

John