Pressure in a propane tank, large or
small, can range between 100 and 200 psi. This propane pressure
must be reduced and regulated for use in a home, motor home,
camper, or an outdoor gas appliance.
Typically, a residential application will require a
regulator which reduces the gas pressure to 6 ounces (10.5
inches water column).
This low pressure regulator will be located on or near the main
tank supplying gas to the home, motor home, or camper.
Outdoor gas appliances may access low
pressure propane gas through a
outlet located somewhere after the low pressure regulator or
from a separate, portable tank like the kind you see at Home
Depot or Lowes. Portable tanks also require propane
pressure regulation. Sometimes a low pressure regulator is
built directly into the gas appliance and sometimes one must be
installed on the portable tank itself. Check with your gas
appliance manufacturer to see what propane pressure the
appliance requires at the inlet on the gas appliance.
Some outdoor gas
appliances, such as
high heat cast
iron burners, require the use of a
because they need more volume of gas than a low pressure
regulator will deliver. A high pressure regulator will regulate
the output pressure from 1 psi to as high as 60 psi. There are a
number of different high pressure regulators available.
Some high pressure regulators are "preset".
That is, the propane pressure is fixed at, for example, 10 psi
or 20 psi. Further attenuation of the gas delivered to the
appliance may be done by use of an inline ball valve or needle
control valve located either on the hose or built into the
The other common type of high pressure regulator is an
"adjustable" high pressure regulator.
Adjustable high pressure regulators are available in 0-20 psi,
0-30 psi, and 0-60 psi versions and have an output pressure
adjustment control built directly into the regulator. Depending
on the number of btu/hr that the gas appliance(s) require, one
chooses the adjustable propane gas regulator which gives the
required number of btu/hr. Choose the propane regulator that is
the closest match. There is no advantage of having a propane
regulator with a lot more btu/hr than you actually need. As you
increase the btu/hr output of a propane regulator, the degree of
control that the internal propane regulator valve has over the
gas output decreases; i.e., turning the valve an 1/8" in a 0-60
psi adjustable propane regulator has a lot more effect than
turning the valve an 1/8" in a 0-20 psi adjustable propane
Folks frequently ask:
"How long will my portable tank of propane last?"
This is easy to figure out if
you know the number of pounds of gas that is in your full tank
and the btu/hr demand of your burner or other gas appliance. One
pound of liquid gas in your tank has 21,591 btu/hr fuel value.
The most common tank is a 20 pound tank (also sometimes referred
to as a 5 gallon tank). This is the kind of portable tank you
would find at a Home Depot, Lowes, etc. If you have a
burner, for example, that is rated at 40,000 btu/hr maximum
output then you can run that burner at full blast for 10.8
hours: (20# x 21,591btu/# = 431,820 btu is the gas in a
20# tank, 431,820 btu ÷ 40,000 btu/hr = 10.8 hrs) . On the
other hand if you have a high heat,
high pressure burner that is rated at 160,000 btu/hr maximum
output you can run that burner at full blast for only 2.7 hours.
In practice, it is unusual for anyone to run a burner at full
throttle for that long so you will probably not empty the tank
this quickly. The point is that if you want to develop the heat
in an uninterrupted manner you have to plan for adequate propane
tank reserves. Experienced chefs keep a spare propane tank
around. These figures are theoretical. According to a
major 20 pound propane tank producer, Blue Rhino, their 20 pound
propane tank will only contain about 4.1 gallons of liquid
propane which weighs just 17 pounds. The empty propane
tank weighs about 20 pounds so if you add the 17 pounds of gas
you have a full propane tank weighing around 37 pounds.
Folks also ask: "What
is the pressure inside my portable tank?"
According to the publication NFPA58, a tank with 20 pounds of
gas at 70°F
would have a pressure of 145 psi, at 90°F would have 180 psi, at
105°F would have 235 psi, and at 130°F would have 315 psi.
If the tank is filled with only 17 pounds of fuel then the
internal pressures would be somewhat lower than those just
One of the common complaints
I hear is: "My
propane regulator is icing up and the propane output is
A single stage, high pressure regulator will expand the volume
of the gas from a liquid state to a gas just before the point
that the gas hose is attached to the propane regulator output.
That change of state from liquid to gas requires a considerable
amount of heat. The heat comes from the metal that surrounds the
gas in that area. If the demand for the propane is very high,
the metal gets noticeably colder and colder because it can't
draw heat from the surrounding area fast enough. If the
demand for gas is very high and
there happens to be a high moisture content within the propane
stored in the tank, the water vapor can condense and freeze up
internally within the regulator (a cold metal enclosure) thereby
block the flow of the propane to the supply hose.
What can you do?
Well, you can complain to
your retail gas supplier. Ask them to purchase the gas
from the gas wholesaler that will inject some methyl alcohol
into the propane...methyl alcohol acts as an antifreeze.
Wholesale propane gas suppliers often do this in the winter
months in colder climates. If that is not feasible then
occasionally pour some warm water over the propane regulator.
Also try to keep the propane tank and gas regulator in a warm
place. The colder the propane tank and gas regulator are, the
more prone the gas regulator is to experience a freeze up.
Lastly, keep a spare propane tank and be prepared to make a
switch whenever you sense a decrease in the flow of the propane.
Then allow the cold propane tank and regulator to warm up. The
problem will be more pronounced with a less than half-full or
near-empty propane tank, and occurs more frequently in a smaller
propane tank than a larger propane tank. Experienced
caterers always use as large of a propane tank as they can and
keep a spare tank nearby.
also ask: "What is a btu?"
A btu, or British Thermal Unit,
is the amount of energy required to raise one pound of water one
degree Fahrenheit. A gallon of liquid propane contains
91,502 btu's. A pound of liquid propane contains 21,591
Another often asked question is "I have a low pressure
regulator but it does not seem to supply enough gas for my
Unfortunately, many of the preset low pressure regulators
available in the marketplace use 1/4"ID hose and some are
attached to a propane regulator with a 1/4" NPT (normal pipe
thread) outlet on the propane regulator. There is a limit
to the volume of gas that can be delivered through this small ID
hose at a fixed low propane pressure of 6 ounces .
What can you do?
Use a low pressure regulator
with a 3/8"ID gas outlet and a gas hose of 3/8"ID. The
amount of propane that can be delivered to the appliance is
increased by a factor of 2.26 so the chances of starving your
appliance for propane are greatly diminished.
GasHosesandRegulators.com sells only 3/8" NPT outlet low
pressure gas regulators and 3/8"ID low pressure hoses for this
very reason. Our grey hose carries UL , CSA, and American
Gas Association approvals and is designed to supply up to about
100,000 btu/hr of propane gas.
Why does my grill have little or no flame?
According to the Coleman company
there are at least three possible reasons. First is
that the propane tank might have been improperly filled.
All tanks must be purged of air before being filled with gas.
This purging requires filling with a small amount of gas and
then emptying. Propane is heavier than air and will force the
air out of the tank during the emptying. Filling with gas then
can proceed. If the tank is not purged then the air is the
first gas to exit the tank and the grill will either have no
flame or a very low flame for possibly over an hour until the
air does fully exit the tank. A
second cause might be the automatic activation of a surge
protection device within the propane regulator. If, for example,
you turn on the tank valve before you fully turn off each of the
burner knobs on the grill the surge protector will likely sense
a leak and activate. The fuel flow will be very low.
The remedy is to turn everything off, disconnect the tank, and
reconnect everything before starting over. A third
possible cause might be that the tank was overfilled.
All propane tanks are now fitted with Overfill Protection
Devices (OPD) which is designed to be activated by a float
valve. The OPD feature prevents overfilling of the tank by
shutting off the valve. A 20% empty space is necessary to
prevent the tank from venting large amounts of propane when the
ambient temperature rises. This OPD can also be
inadvertently activated by tilting a very full tank during
One gallon of water weighs 8.33 pounds. It takes one btu
to raise each pound of water 1 degree Fahrenheit or 8.33 btu's
to raise one gallon of water one degree Fahrenheit.
Knowing that, it is straightforward to calculate the number of
btu's required to raise a known number of gallons of water to
boiling...assuming 100% thermal transfer of the heat from the
flame and assuming you know the starting temperature of the
water. This becomes useful in determining approximately
how long your tank of gas will last.
Volume to volume propane delivers more btu/hr than natural gas.
For example, at 60 °F a flow of 1 cubic foot/hr of natural gas
will deliver 1030 btu/hr but 1 cubic foot/hr of propane will
deliver 2488 btu/hr...about 2.5 times more heat.