Systems and Maintenance

Propane System Maintenance and Safety

Bill Ward, Owner of Hallmark RV, helps to demystify the safe use of propane and propane systems in a truck camper.  Crack the petroleum, it’s a gas!

Camper Propane Safety

When we got our very first used truck camper, we spent the night at Gordon’s grandparent’s house to test out the systems before hitting the road.  At about 2:00am the propane / LP detector started beep, beep, beeping at us.  Of course we freaked out and ran out of the camper thinking it was going to explode.

Flashlights in hand, we poured through the bag of manuals that came with the camper looking for some answers.  A few frantic moments later we read that propane / LP detectors will go off if your camper batteries are too low.  We checked our batteries and sure enough, they were low.  We weren’t about to explode after all.  A few laughs later, we went back to bed.

Ever since that event, we’ve heard countless stories about other newbies who have had similar experiences.  Obviously we needed to address proper propane use and safety in a truck camper.  When Bill Ward, Owner of Hallmark RV, confessed that he was very interested and knowledgeable about the subject, we had finally found our expert.  The following article is the result of our conversation with Bill.

Update: Following the initial publication of this article, Manchester Tank and Equipment, contacted us with some further insights into this important subject.  With their help, we updated the article with more information on propane system maintenance and safety.

What is propane?

Propane, also known as liquid petroleum gas, LP-gas, and LPG, is produced in roughly equal amounts from both natural gas and crude oil sources.  Propane is nontoxic, colorless, and odorless until an odor similar to rotten eggs is added to allow the gas to be quickly detected.  Knowing this smell is very important to your safe use of propane.

To make propane from crude oil, the oil is separated at a refinery using a fractioning tower.  Propane is refined into different levels of purity depending on what height of the fractioning tower the propane is pulled from.  The higher the point on the fractioning tower, the higher the purity, or quality, of the propane.

In the warmer southern states, you are buying propane with more butane, which is at a lower cut point, or crack of the fractionating tower.  In the colder states, you are using a propane that is from a higher crack that is more pure, therefore it can be a little more expensive.

Propane bought in a more tropical climate is not going to be as pure and therefore will not be the quality of propane you need to camp in a colder climate.  That means that if you are traveling from a warmer to colder climate, you should use up your propane before getting to the cooler weather.

The quality of colder weather propane is better, so people traveling from cooler to warmer climates are fine.  It’s also okay to mix propane from cold and warm climates.  The general rule is to use propane from the climate you are in.

Propane Cylinders

Truck campers have either horizontal or vertical DOT (Department of Transportation) propane cylinders (also known as containers or bottles).  It is very important to use only vertical DOT propane cylinders in campers designed for vertical cylinders and horizontal DOT propane cylinders for campers designed for horizontal cylinders.  If a propane tank has a collar with a stamp and you can pick it up, it’s a DOT propane cylinder.

Inside a DOT propane cylinder, there is a fixed maximum liquid level gauge.  There is also an overfill prevention devise, or OPD, that acts a like a toilet float to prevent overfilling.  These mechanisms are oriented for horizontal or vertical use in horizontal or vertical propane cylinders.  This is why it’s critical to use the correct vertical or horizontal cylinder in your propane system.  Horizontal DOT propane cylinders are easy to recognize as they have feet on them.


There is a lot of information on a propane cylinder including the date the cylinder was manufactured.  Propane filling attendants look at this date to know how old your cylinders are.  Different states have different regulations on how old your propane cylinders can be.  For example, in Colorado, the regulation states that propane cylinders can be no more than twelve years old.

Bill explained that propane cylinders should only be filled to 80% capacity.  It’s extremely important to not overfill a propane cylinder as it could allow liquid propane into your propane fueled appliances.  Not only could this be a fire hazard, but it could also freeze and damage propane regulators.

Propane expands 1.5% for every ten degree increase in temperature.  As a liquid, propane doesn’t compress like a gas and needs room to expand safely.  By filling your propane cylinders to 80%, you prevent this potential expansion from creating a dangerous situation.

For example, say you filled your propane cylinder to 92% when you started your trip in Minnesota.  At the time you filled your tanks, the temperature was 30 degrees fahrenheit.  From there you drove to Florida where it was 70 degrees fahrenheit.  The propane liquid expands with the rise in temperature until the relief valve discharges propane.  This discharge of liquid propane is dangerous and could fuel a fire.

Purge and Fill Your Propane Cylinders


Before the first filling of a new propane cylinder, you need to make sure that your cylinder has been purged.  During a propane purge, the technician injects a small amount of methanol under pressure into the cylinder.  This ensures that no moisture or impurities are in the cylinder that could contaminate the propane.


The first thing you need to do when filling propane is to turn off the camper appliances that run off propane; the hot water heater, furnace, refrigerator, stove, and oven.  Then turn off the propane using the turn valve at the top of the cylinder and carefully remove your propane cylinders from your camper.

Filling propane is not like filling with gasoline or diesel.  With propane, an attendant at a filling station fills your propane for you.  Make sure you keep a safe distance as they are filling as propane is discharged during the filling process.  Before filling the cylinder, the attendant will use a screwdriver to open your propane cylinder to allow propane to escape.

As the attendant is filling your cylinders, you should notice that he/she is using a scale to measure the amount of propane going into the cylinder.  For example, if you have a thirty pound propane cylinder, you have thirty pounds of propane going into the tank plus the weight of the cylinder.

The empty weight of a propane cylinder is shown on the propane cylinder.  On the collar of the cylinder, it shows you a TW in pounds or T in kilograms.  This will show you the weight of the cylinder empty.  For example a horizontal cylinder can be 27 pounds and a vertical can be 24.5 pounds empty.  This is because the horizontal cylinders have feet, so they will weigh slightly more.  The collar tells you what the weight of the empty cylinder is and then you need to add in the weight of the propane.  That’s how you get the filled weight.

WC on collar means water capacity in pounds and .42 is the fill density.  You multiply the water capacity of container x .42 to tell you the maximum amount of propane to put in your container.  A standard propane twenty pound cylinder’s WC is 47.6 x .42, which equals 19.99 pounds.  Most attendants have a chart of the most common propane weights.

When the propane cylinder gets 80% full, liquid propane gas will escape from the cylinder through the required fixed maximum liquid level gauge in your tank.  The fixed maximum liquid level gauge is the piece that the screwdriver will attach to.  When the liquid propane reaches 80% full in the propane cylinder, you will see a white mist of propane coming from the propane cylinder.  The propane mist looks like the vapors from dry ice.  Be careful not to touch the white mist because the material is forty-four degrees below zero and can cause freeze burns.  When the attendant can hear but not see the propane mist anymore, the cylinder has been filled to the correct level.

If an attendant overfills your cylinder, ask him/her to bleed your cylinder so that it is no more than 80% full.  Again, you will know that the cylinder is at the right level when you can hear but not see the propane mist.

Putting the Tanks Back into the Camper

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After your propane cylinders are filled and properly placed back into the camper propane compartment, connect the black propane hoses to the propane system.  The black propane hoses have green connecting knobs that turn clockwise onto the corresponding connector on the propane cylinders.  Tighten these green knobs by hand only.

Once the green knobs are tightened, check for leaks with an approved leak solution before opening on the valves.  Soap and water sprayed on the connections work well.  If the soap bubbles around the connections, you have a leak.  Don’t use Windex or household cleaners with ammonia as it can make brass brittle and cause them to fail. Use only ammonia free soapy water.

Once you’ve checked for leaks, you can open the valves on your propane cylinders.  With the cylinders open, close the propane compartment door and enter your truck camper.  With at least two windows open in your camper for proper ventilation, turn on your propane stove.

Your propane stove is the largest propane orifice in your camper.  When it properly ignites and runs, you ensure that propane gas is properly moving through your propane system and any air in the propane lines has been purged.  It is also a good idea to briefly turn on your hot water heater and furnace.  With your stove, hot water heater, and furnace now running, propane should be flowing properly throughout your propane system.  You can now turn these appliances off.

The last propane appliance to turn on is your refrigerator.  You will find it lights more quickly when the other appliances have been started because the propane is already flowing properly through the lines.  A refrigerator has the smallest orifice in a camper and is the appliance that uses the smallest amount of propane.  In fact, Bill told me that he bets that if the only appliance you ran was the refrigerator, you could probably run it almost a year on one cylinder of propane.

Reading Your Propane Gauges


There are two gauges that you can use to monitor the level of propane in your propane cylinders.  The first set of gauges is located on your propane cylinders.  These gauges show the approximate quantity of propane in your cylinders.  Keep in mind that propane expands and contracts with the temperature changes, so it is not as accurate as your fuel tank gauge on your truck.

The second gauge that helps to monitor the level of propane in your propane cylinders is a dial located on the propane regulator.  This dial should show either red or green.  When the dial is red, the propane cylinders are empty.  When the dial is green, there is propane in the tanks.  This dial does not tell you how much propane is left in the system.

The Propane Regulator

Propane Regulator

A propane regulator controls the gas flow to the appliances in your truck camper.  You can find the propane regulator mounted on the top or side of your propane compartment.

Most truck campers have two stage propane regulators.  The first thing that happens with a two stage propane regulator is that the propane fuel flows into the first stage.  If the propane fuel is not pure, the first stage will fail.  You will know this has happened if you see a honey like substance (solid propane) leaking out of the drain hole in the first stage of the regulator.  You will also smell propane escaping out of that hole.

If you see the honey like substance leaking out of your regulator, it means that you need to get your regulator replaced.  When you take your camper to a dealership, insist on a two stage propane regulator.

Bill recommends having your propane regulator replaced by a technician every few years.  He also recommends replacing an older regulator before a long trip, especially if you will be changing elevations.  New propane regulators are better able to adapt to altitude changes.

Propane System Maintenance

You should have your truck camper propane system checked and maintained every two years by a certified propane technician.  The technician will check your camper’s propane system for leaks, inspect the condition of your valves and fittings, and make sure your cylinder is free from corrosion, dents, and other damage.  The technician should also check that propane supply lines are not rubbing against other objects.  Damaged propane equipment or lines should be immediately replaced by the technician.

Propane / LP Detector


The propane / LP detector in your truck camper is designed to alert you if you have a propane leak in your truck camper.  The propane / LP detector should be located near the interior floor of your camper because, in the event of a propane leak, propane acts like water and pools at the lowest point of your camper.

If your propane / LP detector goes off, you should immediately open the main camper door and leave the unit.  Do not light a cigarette, turn on electric switches or appliances, or electronic re-igniters as these actions could trigger an explosion.  Leave the camper door open and the propane should dissipate quickly.  Propane is heavier than air so it will flow out of your camper quickly like water falling out of a bucket.  Once out of your camper, immediately close the supply valves on your propane containers and do not open them until the problem has been corrected.

Bill also told us that propane detectors can be triggered by perfume, wet pets, and bad pet breath.  Even if you suspect that the propane / LP detector alarm was triggered from a source other than propane, the safe thing to do is exit the camper and allow the air to clear.  Once the air has cleared and you return to the unit, you could put the perfume or other suspected source in front of the detector to see if it triggers an alarm.

Checking Your Propane / LP Detector


Every propane / LP detector has a date on the detector for when that detector should be replaced.  Most propane / LP detectors last about five years.  If your LP detector is out of date, replace it immediately.

An easy test for a propane / LP detector is to activate, but not light, a portable propane lighter next to the propane / LP detector.  If the propane / LP detector is working, the detector should quickly activate with an alarm.

Without a working propane / LP detector, you may not smell the propane pooling on the floor of your camper as you sleep in the overcab.  That can lead to some extremely dangerous situations that can be avoided with a fully functional propane / LP detector.

Beep: Low Batteries and Propane / LP Detectors

Another reason a propane / LP detector may go off is if your camper batteries become low.  If this happens, the propane / LP detector will beep intermittently.  This is a very different and significantly less alarming alert than if there was a real propane leak.  To hear the difference, try the propane / LP detector test mentioned above.

If there is a propane leak in your camper, go to an RV dealer immediately.  The dealer can use a manometer to test the propane system.

Carbon Monoxide Detector


Your camper should also have a carbon monoxide detector positioned high up on the interior of your camper.  The carbon monoxide detector detects the burned propane gas that is emitted from your stove or other propane appliances.  This burned gas is toxic and should not be breathed.  Unlike propane, carbon monoxide does not have a smell but the carbon monoxide detector will pick it up.

Most carbon monoxide problems occur because people heat their camper with a stove, which does not vent to the exterior of the unit.  Naturally this is extremely dangerous.  Never use stove burners or ovens to heat your truck camper.

Symptoms of carbon monoxide poisoning include headaches, nausea, dizziness, drowsiness, confusion, impaired judgement, and loss of manual dexterity.  If anyone shows symptoms of carbon monoxide poisoning, seek medical attention immediately.

Driving the Truck Camper With Propane

More than any other RV propane topic, driving with the propane on is the most controversial.  Proponents of driving with propane on argue that it’s no more dangerous than driving a car with a tank full of gasoline.  Opponents to driving with propane on state that propane lines can break during an accident and the resulting propane leak could be explosive.

This article is about propane safety.  The safest way to travel with propane is with the propane turned off.  You lose the convenience of having your refrigerator run while driving, but you gain the peace of mind of being safe as you travel.

Propane Cylinder Swapping

You should be careful if you decide to swap or exchange twenty pound cylinders.  You may get cylinders that are not Department of Transportation (DOT) approved.  In a truck camper, it is very important that you always use DOT approved cylinders.  They may be three times the cost, but DOT approved tanks have a thicker skin are designed to be crushed without exploding.


When you winterize your truck camper, you do not need to drain your propane cylinder.  It is fine to keep propane in your cylinder over the winter.

In the spring, you want to make sure that you check your outside propane appliance compartments for the nests of bees, hornets, and spiders.  These critters love the smell of the additive in propane and will build nests in the exhaust.  If you see a thick black smoke coming out of the exhaust of your water heater or furnace, it pretty much guarantees that there is a nest inside.  If you have a nest, clean it out immediately or take your camper to a RV dealership center for service.

Eleven More Important Propane Safety Tips


1. Be cautious of the dials on your stove.  If the stove dials are turned on and the stove is not lit, the stove will release propane gas into the camper interior.  Kids and dogs have been known to move stove dials, so you may want to remove the stove dials if you have kids or dogs (see left dial).  That should ensure that the dials do not get turned on by accident and cause a dangerous propane leak.

2. Anytime you are in your truck camper, you should have a window cracked open at least one half inch.  When cooking, turn on your range hood fan to remove the moisture and combustion exhaust from the stove top or oven.  Truck campers are relatively air tight and need to have ventilation.

3. You may notice that the flames on your stove sometimes change color.  A significant amount of orange flames probably means that you have a large amount of impurities in your propane.  This could happen because there is a low oxygen content in your camper or because you have low fuel in your cylinder.  It could also be a sign that your regulator is starting to fail.

4. At a fuel station, you should turn off your propane cylinders and any burners, pilot lights, or automatic ignition appliances before pulling up to the fuel filling area.  When going through a tunnel or traveling on a ferry you should also have your propane turned off.

5. When you gain altitude, you lose propane gas pressure, which will make all of your appliances less efficient.  At altitude, your regulator needs to work harder.  For this reason, Bill recommends campers with electronic ignitions for their water heaters and refrigerators.

6. Don’t use portable propane camping equipment in your truck camper.  For example, camp stoves, barbecues, lanterns, catalytic converters, and radiant heaters.

7. Always inspect your propane cylinders s for signs of damage including corrosion, exposure to fire, or possible leaks.

8. When transporting your propane cylinders, always transport them in their secured upright position in the truck camper propane compartment.  Never use, store, or transport propane cylinders in the passenger space of your truck or camper living space.

9.  Cylinders manufactured before September, 1998 do not have the overfilling protection device and should not be refilled.  DOT propane cylinders can only be used for twelve years after their manufacture date.

10. With horizontal propane cylinders, make sure you park as level as possible.  Horizontal propane cylinders are like Coke bottles on their side.  Parking at an angle can tip the cylinder to a  point where liquid can enter the piping system.  You may not be able to get propane from the tank if the cylinder is not completely full and at an angle.

11. When using propane, make sure there is no source of ignition within twenty-five feet of the propane cylinders.  That also goes for campfires.  When at a campground, you want the campfire to be as far away from the propane cylinders as possible.

For most of us, this article is probably a review of common propane and propane system knowledge and safety.  For others, this article will be an introduction to safe propane use in a truck camper.  Either way, propane will continue to be a critical part of our modern truck camping lifestyle.  Propane keeps our food cold and fresh, cooks our meals, heats our campers, and makes a hot shower possible.  With a little propane knowledge and respect, you can enjoy the many benefits of propane use in a truck camper.

For more information about propane and safe propane use, visit the Propane Education & Research Council website at

If you are thinking about buying a used camper, please read How To Inspect A Used Truck Camper to gain more knowledge about what to look for before your purchase.


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