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Keep Your Propane in the Tank (you won’t like it anywhere else!)

April 20, 2012

We’ve had verified sightings of sunny weather!  Warmer weather means outdoor grilling.  The easiest grill to fire up is the propane barbecue.  Propane is a pretty inexpensive fuel and it’s very clean to burn.  This summer we’d like you to remember three things about propane.

First of all, propane is a relatively heavy molecule.  If released it will sink to low spots and wait for an ignition source.  Any ignition source can ignite an explosion.  Consequently portable propane devices are not licensed nor designed for use indoors.  Read that again.  Portable propane devices are NOT to be used inside the house, inside the garage, or inside most structures.  In some construction applications propane heaters are allowed, but even then there are hazards.  Residential central heating furnaces can be designed to use propane safely.  As a rule, however, portable propane-burning devices are not for use indoors.

Secondly, propane is compressed into metal cylinders as a liquid, hence the term LPG, or liquid propane gas.  If you shake a propane cylinder, you can hear liquid sloshing around.  Consequently you have a lot of pressure inside that metal cylinder.  So for safety’s sake, the cylinder is only to be filled 80% full of liquid.  That leaves 20% of the cylinder to deal with pressure fluctuations.  Why would propane cylinder pressure fluctuate?  A change in outdoor temperature can do that.  In the shade, a full propane cylinder will maintain a constant internal pressure.  In direct sunlight, the temperature of the cylinder goes up, and cylinder pressure rises.  If you have 20% vapor capacity, the cylinder can withstand that pressure increase just fine.  If the cylinder is filled to 100% something has to give.  In Washington State all propane cylinders must have overfill protection devices to ensure 20% vapor capacity.

Lastly, to avoid explosions, propane cylinders have pressure relief devices.  At a certain pressure the pressure relief device will open and release propane gas to avoid a very messy cylinder explosion.  Sounds safe, right?  Sort of.  Avoiding a cylinder explosion is good, but releasing propane gas takes us back to pooling in low spots and waiting for an ignition source.  So we like to avoid releasing propane gas.  Overfill protection devices help but you can also help by keeping your propane cylinder cool.  Keep full propane tanks out of direct sunlight.  Ensure propane tanks don’t get heated by the device being fueled (propane beneath the barbecue is okay since heat rises).  On a hot summer day, a full propane tank in direct sunlight may start leaking at the pressure relief valve.  Move it to a shady spot (outdoors of course) and put a cool wet towel around the neck of the tank.  That will probably take care of the problem.  You can also connect the tank and start using the propane to consume some of the product and reduce cylinder pressure.

Pressure relief devices only work if the device is upright.  So never lay an upright propane tank on its side or upside down.  Doing so defeats that safety device and is dangerous.  Propane powered vehicles are designed with horizontal tanks and have pressure relief devices for that orientation.  Portable propane cylinders for barbecues and the like must be used in the vertical position only.

Remember these tips and you should do just fine with your summer barbecuing.  If you’ve got questions about propane give us a call at 466-4602, or e-mail me at dbleeker@scfd9.org, or you can post your question here in the comments section of this blog page.

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From → Fire Prevention

One Comment
  1. Stephanie permalink

    I was barbecuing tonight with a propane tank that a friend gave me. and when I went to turn off the barbecue the propane valve was so hot I couldn’t touch it and the tank was hot. I had to get a cloth to shut it down and I emptied out the lines going to the BBQ and left everything open to cool down. why did this happen? Freaked me out!!!

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