Date:         Fri, 11 May 2007 13:01:27 -0700
Reply-To:     Robert Keezer <warmerwagen@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Robert Keezer <warmerwagen@YAHOO.COM>
Subject:      Re: propane explosion sleep with one nostral open
In-Reply-To:  <341778.54454.qm@web38903.mail.mud.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

I add a correction here. Gary is right- If the
pressure regulator fails, it can also deliver
high pressure liquid propane to the appliance.
Since Westfalias have factory 2-stage regulators,
the second stage does prevent higher than 11"
water column pressures to the appliance.
Boats also have a electric solenoid valve to
prevent regulator leakage to the cabin when not
in use.

Replacing the dual with a single stage does
increase the risk of high pressure gas or liquid
propane at the appliance. The standard pressure
output of a single stage is 5 psi.

 As Gary pointed out, the risk is pressure that
is higher than this . But the risk is only if the
appliance is in use. If the appliance valves are
off, the gas cannot enter the vehicle unless the
fittings leak.

The fridge burner has a very small orifice. It
acts like a restrictor, so and too high pressures
here will put the flame out, and the thermocouple
will then shut off the gas.

The Westy stove does not use a thermocouple
because it wsn't designed for 24 hour use.

This would make it safer, in case your stove was
on, ran out of gas, then you fill the propane
tank without first turning off the stove knob.


The two-stage then prevents too low or too high
pressure at the appliance, when the appliance is
in use. Pressure differences in a gas appliance
changes the air/fuel ratio fo that appliance.

Maintaining a consistent pressure insures clean
and effecient combustion, plus proper heat output
for the refrgerator burner, and stove.


If the appliance valves are off, and the
regulator fails, this failure is usually gas
leakage to the outside air.

The secondary regulator stabilizes pressure.


Single -stage failure usually results in
regulator leakage .I have not seen super high gas
stove pressure with flames soaring or a gigantic
cloud of propane, but it can happen.

The safety of the two-stage is that if a
inexperienced attendant should overfill the the
tank, the second stage regulator will not allow
more the the standard allowable  water column of
pressure at the appliance.

AN overfilled tank is dangerous because it has no
vapor space, the 20% min air space required
above the liquid propane in order for it to
become a gas,  thus preventing liquid propane
from entering the appliance.

This space is also for expansion of the liquid
propane in hot weather.

Without this space in hot weather, the tank
pressure will increase, and the liquid propane
can freeze the the regulator, rendering it
inoperative.

In this case , whether one or two stage,
operating an appliance such as the stove is
dangerous due to the potential for liquid, not
gasified propane, entering the appliance . Liquid
propane acts as a refrigerant and can freeze
flesh on contact. It also expands rapidly and can
easily fill the interior of a camper Vanagon in
seconds if it enters in liquid form.

This is why all RV tanks have an 80 % fill
requirment and an 80% valve that lets the
attendant know when to turn off the gas and
prevent filling up the last 20% air space.

If the two-stage regulators only job was to
prevent liquid propane from entering the vehicle,
then the 20 % expansion space would not be
needed.

I have replaced many leaking Vanagon 2-stage
factory regulators. They are old. Now is a good
time to replace them with a new 2-stage for about
$30.00. You have to be careful, but it can be
done without damaging the pipes when installing
the longer new regulator.


Robert

1982 Westfalia














--- gary hradek <hradek@YAHOO.COM> wrote:

> Robert,
>       I assumed that when the regulator fails
> in a
> single stage that the unregulated gas pressure
> can
> overcome the two devices inside the westy?
> All
> camper vans are required to have dual stage
> regulaters
> so that the second stage acts as a backup.
> When the
> first stage fails a small leak external to the
> vehicle
> alerts the user that there is a problem.   VW
> did not
> allow enough space for the new dual stage
> regulators
> so it is a temptation to install a smaller
> single
> stage regulator that does not require bending
> the
> pipes.   This should not be done.   Gary
> --- Robert Keezer <warmerwagen@yahoo.com>
> wrote:
>
> >   So sleep very well in your
> > > westy
> > > unless you foolishly used a single stage
> > > regulator
> >
> > This claim is not true, and would place the
> leak
> > outside the vehicle,  when the report places
> the
> > leak (and explosion)inside .
> >
> > If the leak was from outside, the vehicle
> would
> > have to be in a depression where the
> sorrounding
> > ground was higher.
> > Then the gas could get into the van through a
> > window, or other opening.
> >
> >
> >  Not likely of there was a wind,or a slope -
> > propane is heavier than air and will seek
> lower
> > ground before dissapating.
> >
> > A motor vehicle driving through a cloud of
> gas
> > can set it off.
> >
> > The regulator itself whether one or two stage
> > wasn't  the cause . The second stage prevents
> > pressure fluctuations in apppliances only.
> > It maintains en even pressure and helsp
> offset
> > pressure variations due to ambient
> temperature.
> >
> > Whether a one or two stage,  this does not
> mean
> > it is  any safer with regard to it leaking
> > outside the vehicle.
> >
> >  When a regulator leaks, the diagphram has
> failed
> > and both  one and two stage regulators have
> them.
> > 2 stage has two diagphrams.
> >
> > The regulator is on the tank outside the
> camper.
> >
> > The explosiong was inside the camper. It blew
> the
> > front windshield out.
> > How will gas igniting outside the vehicle do
> > this?
> >
> > Robert
> >
> > 1982 Westfalia
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > --- gary hradek <hradek@YAHOO.COM> wrote:
> >
> > > I think the actual event that started this
> > > thread is
> > > very rare and is likely to have been easily
> > > prevented.
> > > The stove and the fridge may be the usual
> > > suspects but
> > > not the unusual suspect here.  It is easy
> to
> > > leave the
> > > burner on but that is not what happened,
> unless
> > > your
> > > too high to notice it.   I can think of two
> > > causes.
> > > One is it was intenstional and the other is
> > > that a
> > > single stage regulator was used instead of
> a
> > > dual
> > > stage regulator.   So sleep very well in
> your
> > > westy
> > > unless you foolishly used a single stage
> > > regulator
> > > because it fit better or was cheaper and if
> you
> > > are
> > > not sure, would not hurt to check what the
> > > previous
> > > owner did for you.   Gary
> > >
> > > I was told this is likely a regulator that
> is
> > > slowly
> > > failing. They tend
> > > to vent some gas to the air
> > > when the tank pressure gets very low, or at
> > > least that
> > > is how it was
> > > explained to me. I had
> > > mine tested at a shop when the tank was
> full
> > > and no
> > > leaks were found,
> > > so this was his theory.
> > > It seems to be true, as I only smell it
> when
> > > the tank
> > > is nearly empty.
> > > I bought a new regulator
> > > from GoWesty but still haven't installed
> it.
> > >
> > >
> > >
> > >
> > >
> >
>
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