Date:         Tue, 01 Nov 94 10:55:51 CST
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         "J. Walker" <JWALKER@ua1vm.ua.edu>
Subject:      for campers: Propane Safety


Propane Safety                    <Trailer Life, August 1994>
   by Rich Johnson

Propane, or liquified-petroleum gas (LP-gas), is a "natural" fuel for
RVs.  Because of its portability and resistance to temperature
extremes, LP-gas has been used in RVs since the early years.  This
incredible gas supplies both heat and cold to RV appliances, making
it an indispensable product for year-round travel.

Although flammable gases can be dangerous when mishandled, hazardous
situations can be avoided with proper handling and by taking simple
precautions, which are necessary with any fuel.  Knowledge is the key to
dealing with any potentially dangerous substance, and so it is with
propane, which is a very volatile fuel, normally kept under high pressure
as a liquid;  it expands into gaseous form when released into lines
leading to appliances.  Propane is a petroleum product separated out of
the natural-gas or crude-oil streams during the refining process.

In its unmodified form, propane is odorless and colorless.  For commercial
use, an odorant is added that smells like rotten eggs.  This is to serve
as an alert mechanism in the event of a leak.

SAFETY PROCEDURES
When propane escapes, it can easily result in explosion and fire, if a
source of ignition is present.  Under the right set of circumstances,
it is possible to ignite escaped propane by simply turning a light switch.

At times, propane may act in ways that appear unpredictable.  However,
there is always an understandable reason.  In the event you smell
propane, take action immediately:

1.  Postpone using the barbecue!  Don't do anything that could cause a
    spark of flame.

2.  If propane is released inside the RV, don't turn any electrical
    equipment on or off.  Using electrical switches may create sparks.
    Be sure to turn off the gas range.

3.  Without creating a panic, get everyone out of the RV and move them
    a safe distance away, leaving the door open.  Turn off the propane
    valve(s) on the cylinders or tank.  Get away from the vehicle and
    give the propane time to dissipate.

4.  After the propane odor has dissipated, re-enter the RV and open all
    the windows and roof vents to allow free air circulation.  Take care
    not to enter or create any sparks or flames until you are positive
    all propane has dissipated, including that which might be trapped
    behind cabinetry.

5.  Locate the source of the leak and have a trained service technician
    correct the cause.

If the LP-gas has been released outside the vehicle at a cylinder or
tank via the pressure-relief valve, and no propane apparently is inside
the RV, turn off all electrical and LP-gas appliances, including the
refrigerator, water heater and furnace.  Use the appliances' control
switches, which will shut off the automatic igniters.  Exit the vehicle,
closing the door.  Move away from the RV quickly, and call the local
fire department or an LP-gas technician for assistance.  If neither is
available, wait until the gas release has stopped and the propane smell
has dissipated.  Direct a strong stream of water at the tank to cool it,
helping to prevent another release.  Then seek expert help to correct
the problem, which almost always is overfill.

In the event of a release of gas from the pressure-relief valve, don't
curse the equipment;  it is only doing what it is designed to do.  The
pressure-relief valve is venting excess pressure caused by overfilling
into the atmosphere so the safe pressure level inside the tank is not
exceeded.  Never plug or tamper with the pressure-relief valve.  The
real problem here is that there is too much propane in the tank and high
ambient temperature has produced expansion of the liquid and excessive
pressure levels.

To prevent this kind of problem in the future, make absolutely sure that
the LP-gas filling station doesn't overfill the cylinders or the tank.
Routes of travel sometimes increase the tendency of overfill to cause
release of gas.  Filling cylinders or tanks in a cold climate and driving
to a warm climate causes expansion of the liquid fuel and increases
pressures.  However, such a change in climate will not cause pressure
release in a properly filled container.

NATURE OF THE FUEL
By nature, any liquid or gas held under pressure is constantly trying to
get out.  Propane has a boiling point (vaporization) of about minus 50
degrees F.  At that temperature, propane creates no pressure in a closed
container.  As the temperature rises, the liquid fuel begins to vaporize
and build pressure.  Propane grows in volume about 1.5 times for each
10-degree rise in temperature, which is why cylinders or tanks are
filled only to the 80 percent level.

Propane is also about 1.5 times heavier than air.  While it is true that
gaseous propane will naturally seek the lowest possible resting place,
the gas continues to expand as the temperature rises, and convection
currents can stir it around and cause it to circulate throughout an
enclosure.  Prior to filling, or refueling with gasoline, shut off all
gas appliances and extinquish all pilot lights.

TANKS AND CYLINDERS
For use in RVs, there are two different types of propane cylinders.  Each
is imprinted with coded information to indicate certain specifications.
Containers adhering to U.S. Department of Transportation (DOT)
specifications are properly referred to as cylinders, and they're
commonly used on trailers.  They are built with an opening at the center
of a hemispherical dome (or head) at the top, where the valve is located.
A protective guard/handle is built on top of the dome to make carrying
easy and to prevent accidental damage to the valve, the gauge and the
regulator.

American Society of Mechanical Engineers (ASME) containers are called
tanks.  Normally used on motorhomes, they can have openings in the shell
as well as in the head.  Because of this configuration, ASME can rest
horizontally, althouh it is absolutely necessary that they be positioned
correctly to permit proper operation.  Likewise, cylinders must always
be used and transported in the correct position.

Dents, scrapes and corrosion can weaken a tank or cylinder and create a
hazardous situation.  The DOT requiers a visual inspection before filling
any propane container.  Furthermore, filling personnel are not allowed
to fill a propane tank or cylinder that is more than 12 years old unless
it passes a requalification test, is recorded and stamped.  However,
you'll have to take resonsibility to ensure that the service attendant
does the job right.

Hold-down hardware must be inspected frequently.  If a container is
allowed to vibrate and rattle around, damage can be done to such things
as regulators, valves and gauges.  It is also possible for stress cracks
to appear in the vessel itself.  Damaged propane containers can be
repaired by certified shops, but it is then necessary to heat-treat,
inspect and recertify the container before it is put back into service.

Fill valves on are sensitive to dirt, but the automatic stop-fill devices
on motorhome tanks must have their protective dust caps in place when
the tank is not being filled.  Never plug, remove or otherwise tamper
with the stop-fill device.  Repairs should only be done by trained
professionals.

FILLING
There is a maximum allowable limit for filling a propane container, and
it is critical to prevent filling to more than 80 percent capacity.  At
that level, the gauge (if the tank is so equipped) should read full.
But it is a mistake to rely on the gauge to tell you if the container
has enough propane in it or, worse yet, if it has too much.  Use the
gauge only as a reference to show when the cylinder is running low and
needs to be refilled.

During the filling operation, a careful attendant will monitor the
procedure to make sure overfilling does not occur, even if the tank is
equipped with a stop-fill valve.  Be sure to monitor the attendant and
make sure he does the job right.  There are three accurate ways of
preventing the hazard of overfilling the tank.  The most common method
is by properly bleeding propane from the container's liquid-level valve
during the filling operation.  Another is by the use of a stop-fill
valve that automatically discontinues the filling operation when the
tank reaches 80 percent of capacity.  Yet another is by weight, if the
filling station has an accurate scale.  Propane weighs 4.24 pounds per
gallon, so you can easily calculate the amount of propane in a cylinder
of known weight when it is removed from the RV for weighing.

As propane is being pumped into the cylinder or tank, the attendant
should open the liquid-level valve.  On a DOT cylinder, this is done by
turning a screw that is located on the side of the main valve.  On an
ASME tank, the liquid-level valve is likely to be a knurled knob that is
separate from the main valve.  Opening the liquid-level valve will
permit liquid propane to escape when it reaches the point at which the
container is 80 percent full.  When this happens, a stream of white
liquid spews from the valve.  That is when the filling operation should
stop ... immediately.  The attendant should continue to bleed excess
propane from the container until the white liquid disappears and is
replaced by vapor.  Then the liquid-level valve should be closed.

The liquid-level system works on a DOT cylinder via a dip tube that
extends down into the tank.  When liquid propane enters the tube, no
more fuel should be pumped into the container.  Information about the
dip tube is stamped on the valve guard.  For example, it may read DT3.5,
indicating a 3.5-inch dip-tube length, which is typical for a 20-pound
cylinder.  Another stamp on the valve guard indicates water capacity in
pounds.  An example is WC47.7, which means 47.7 pounds of water.  By
moving the decimal point one place to the left, you arrive at the
container's capacity for propane in gallons.  A 20-pound cylinder can
hold 4.77 gallons of propane.

CHECKING PROPANE LEVEL
If the propane container is not equipped with a gauge, it is possible to
determine the fuel quantity by using a couple of tricks.  One is to
weigh the container on an accurate scale, then subtract from the overall
weight the tare (empty) weight that is stamped on the cylinder.  For
example, TW18 indicates that the empty cylinder weighs 18 pounds.
Propane weighs 4.24 pounds per gallon, so if the overall weight is 37
pounds, the amount of propane in the cylinder is 4.48 gallons
(37 minus 18 = 19 divided by 4.24 = 4.48).

Another method for rough calculation is to pour a glass of water over
the cylinder.  If the cylinder is warm, there will usually be an area
of visible difference in the way moisture collects on the side of the
container, creating a line of demarcation where the propane level is.
In cold weather, a frost line may form at the liquid level.

LEAKS
One method of checking for leaks involves using a soap-and-water solution
to paint each connection, then watching for bubbles.  Avoid the use of
harsh chemicals or ammonia solutions that can corrode the fittings.

This type of inspection and testing should be done at the beginning of
the camping season, if you use the RV for only a short period each year.
If the vehicle is used year-round, it's a good idea to run the bubble
test about every four months (or check the system with a leak-detecting
device).

If you detect leaks around the regulator's diaphragm seals or vents, it
calls for replacement of the entire regulator because they are not
repairable.  An owner's inspection of the system involves looking at
everything to make sure it hasn't been damaged or rattled loose.  Check
for signs of corrosion around connections and major components such as
the valve or regulator.  If you find that the gas lines are not tied
down securely, or they chafe against sharp metal edges of the chassis or
coachwork, take steps to correct the problem.  Use rubber grommets or
plastic-wire loom material to protect the gas line from rubbing where it
passes through metal walls.  Install gas line tie-downs (get the ones
with rubber grommets inside and metal straps outside).

PROPANE DETECTORS
Detectors are generally located at floor level.  Some units utilize a
solenoid valve at the tank to automatically shut off propane when a
leak is detected.

The important thing to remember about propane detectors is never assume
that they are giving you a false alarm.  Don't disable a detector simply
because you think it's a nuisance.

There are a few substances other than propane that will trigger a propane
detector;  for example, alcohol, exhaust fuems, paint, cleaners, sewer
gases, glue, even new carpeting.  Some alarms may also sound if there
is a sudden power reduction.  But always assume that the reason the
alarm went off was because of a propane leak.  Evacuate the family and
take all the above-mentioned precautions.  Then take the necessary steps
to solve the problem.

REGULATORS
The job of the two-stage regulator is to reduce tank pressure to the
proper operating pressure that will serve the appliances.  When
functioning correctly, the regulator should provide propane to the
appliances at a pressure equal to 11 inches water-column (WC).  To
determine if the system is working properly, a test instrument called
a manometer is used downstream of the regulator.  A pressure check is
the diagnostic procedure to be performed if appliances are operating
improperly.

Regulators cannot be repaired, and manufacturers estimate about a
15-year life under the best conditions.  Two-stage units must be
positioned correctly in order to maximize the lifespan, with the vent
opening pointing down within 45 degrees of vertical, so that dirt and
moisture do not collect inside and create corrosion or other damage.

In 1977, the RV industry stopped using copper pigtails in the regulators
because of the sulfur in propane odorants caused flaking that fouled the
regulators.  If your RV still has copper pigtails, replace them with
rubber ones that are UL/CGA approved and are equipped with a Prest-O-
Lite (POL) fitting with an integral excess-flow device.

The excess-flow device is a spring-loaded plunger inside the POL fitting
that will automatically close if a sudden rush of propane is detected,
such as would occur if a gas line were to break.  However, it will not
close in the case of a minor propane leak.  If you turn on the tank
valve too quickly, the device may shut down and allow only a minimal
flow of gas to the appliances.  Often it is necessary to turn off the
tank valve, listen for a click, then slowly open the valve to reset the
excess-flow valve.

As you turn on the main valve, always listen to the regulator for the
sound of gas flowing.  This is only a rough leak indicator, but if you
hear the continued flow of gas, something is open somewhere.  It may be
a stove burner that is turned on, or it may be a leak in the line.  Turn
off the LP-gas, then go inside the RV to check that all appliances are
turned off.  If that wasn't the problem, make a thorough check for
damaged lines and leaks at all fittings.  Observe all aforementioned
safety precautions.

Regulators should be covered for protection from the elements. RV
dealers have regulator covers available for just about any setup.
Automatic regulators are used in conjunction with two cylinders that are
connected with a high-pressure hose.  When the valves are opened on
both cylinders, the regulator will operate on one cylinder until it is
empty, then switch automatically to the other one.  When that happens,
an indicator on the regulator shows that one tank is empty.

At that point, the regulator selector knob should be turned to the full
tank, the valve to the empty cylinder should be closed, and it can be
removed for refilling.  If you experience a leak as you try to remove
the empty cylinder from the system, you have either forgotten to turn
the selector knob to the full tank, or you have forgotten to close the
empty tank valve.

TROUBLESHOOTING
Low operating pressure will have a negative impact on appliance
operation.  The problem may be traced to a variety of causes, including
improperly sized, kinked or dented gas lines.  Other causes can be
regulator malfunction, a plugged regulator vent that prevents the
diaphragm from breathing, improper tank position or freeze-up.

Check the regulator vent to make sure bugs haven't nested there and the
vent isn't plugged with dust and debris.  If liquid propane enters the
regulator and creates an interruption of gas flow, the tank has been
overfilled.  Check the liquid level by opening the liquid-level valve
to see if white liquid bleeds off.  If it does, the tanks should be bled
until only vapor escapes.  For safety, have a propane professional
"flare" the propane that is being bled off by using special equipment
and techniques for that purpose.

Freeze-up alludes to moisture in the tank that freezes in the regulator
inlet orifice in cold weather.  Try restoring pressure by pouring warm
water over the regulator.  If that works, the gas has moisture in it.
Solve the problem by having an LP-gas dealer inject some methyl-alcohol
gas line dryer.  Only one pint per 100 gallons is needed, and you must
make sure it comes from a sealed container because alcohol absorbs
moisture from the atmosphere.

There is much to know and understand about propane, but it isn't an
unpredictable or a dangerous fuel when used properly.  Without it,
RVers would have to depend on electricity for water heaters, stoves,
ovens, furnaces, and refrigerators, and few of us would want to be tied
that closely to hookups or an AC generator.  By maintaining the system
and taking responsibility to make sure the filling-station personnel
do their job right, we can rest easy and enjoy all the comforts of home
away from home.