Is Your RV Propane System Leak Free?

Most truck camper owners take pride in knowing how their truck campers work and how to maintain them. This knowledge is enhanced by modifications that personalize and improve the capabilities of the campers even more. Of all the systems in a camper, however, the propane system is the one system that is least understood by owners yet probably gets the most use. This is unfortunate because the propane system, while efficient and safe, can be dangerous in the presence of a leak.

Is Your RV Propane System Leak Free?

Did you know that the propane system in your RV should tested regularly? One of the most important of these tests is what is known as the Timed Pressure Drop Test. All RVs—especially truck campers—should have this test performed annually at a minimum because vibrations caused by rough roads can cause damage to piping and can work propane fittings loose. While this test should be performed once a year, it should also be conducted anytime you smell propane (the ethyl mercaptan put in propane as a warning agent has a distinctive “rotten egg” smell) or when in doubt. Due to its importance, and because specialized test equipment is required, Truck Camper Adventure recommends that this leak test be performed by a certified/qualified RV technician. The information presented here is for educational and entertainment purposes only.

Due to the confined spaces found in most truck camper propane compartments, the best place to perform the Timed Pressure Drop Test is at the range. To conduct this test, the technician will need special test equipment consisting of a manometer (either U-tube, dial, digital, or straight) and a specially-built propane test device consisting of several brass propane fittings. The propane test device, as pictured below, consists of one 1/4-inch FPT brass cross, one 1/4-inch MPT x 3/8-inch male flare adapter, two MPT 1/4-inch x 1/4-inch FPT gas shut-off valves, one 1/4-inch MPT plug (center-drilled with a #31 orifice drill bit that simulates a 50 percent load on the propane system), one 1/4-inch MPT x 5/16-inch host barb fitting, and one 1/4-inch MPT plug. Thread sealant must be used to ensure all male brass fittings in the test device are leak free.

Before conducting the leak test, it’s important to note both the outside temperature and the temperature of the propane system’s piping, which is usually made of copper, but can also be made of iron or flexible rubber hoses. The temperature of both the air and piping need to be approximately the same, and a uniform temperature needs to be maintained for both throughout the test period. Most multi-meters have a temperature setting that can be used to obtain the temperature reading of the propane system’s metal piping.

Conducting the RV Propane Leak Test

The Timed Pressure Drop Test is conducted as follows:

• Open windows and the main door and turn on interior fans to keep the RV aired out. Wear appropriate personal protective equipment.
• Close the service valve on the propane cylinder.
• Disconnect the low pressure propane riser feed from the range’s propane regulator. Use two wrenches to prevent the fitting from being stripped.
• Install the propane test device by connecting it to the low pressure propane riser.
• Connect the manometer to the propane barb fitting on the propane test device.
• Open the service valve on the propane cylinder.
• Open the valve to the propane barb fitting on the propane test device.
• Close the service valve on the propane cylinder.
• Open the orifice valve on the propane test device and reduce the measured pressure on the manometer to approximately 8 inches of water column, then turn the orifice valve off.
• Wait a minimum of 3 minutes (we recommend 10 minutes).
• If there is no drop in pressure after 3 minutes (or 10 minutes), your camper’s propane system is leak free.
• If the pressure drops any amount, there is a leak somewhere in the system and further troubleshooting is required.
• If the pressure slowly increases, this usually indicates either a rise in temperature or a problem with the propane cylinder’s service valve that isn’t closing all of the way.
  
• Remove the test device, reconnect the propane riser to the range’s propane regulator, and conduct a bubble leak test to ensure the propane connection is leak free. Note that thread sealant is not required on compression fittings.

Before conducting the leak test, you might want to perform two other important tests to verify the operation of your propane regulator. The first test verifies the operating pressure of your camper’s propane system, which should read 11 inches of water column with the #31 orifice valve open (this valve simulates 50 percent or more of the btu/hour flow rate of the appliances). A simple adjustment to the propane regulator’s second stage can get the setting just right. The second test verifies the regulator’s lockup pressure, which should rise to about 12 inches of water column with the orifice valve closed. A lockup pressure reading higher than 14 inches of water column indicates that your regulator is “bad” and needs replacing.

Note: the propane regulator found in your truck camper is a two-stage device. The first stage lowers the high pressure propane coming from the cylinder to 10 psi, while the second stage lowers the pressure even more to 11 inches of water column (the equivalent of .4 psi) when properly set.

Some may question the wisdom of conducting a leak test when there is no detectable smell of propane. That’s a fair question. The truth is, sometimes leaks can occur in places where you can’t smell them, like outside the camper, or inside a closed compartment. In fact, some leaks are so small you might not be able to smell them at all. If you find yourself going through an unusual amount of propane you probably have a leak somewhere. Of course, if your camper’s propane leak detector alarm is going off, you should conduct this test as well. You can never be too safe when it comes to propane. Left unchecked, a leak can kill, or at the very least make you sick.

Finding the Leak

If your RV’s propane system has a leak, it’s not the end of the world. Propane leaks are usually easy to find with most being a loose fitting. While using a simple soap and water solution can be an effective way to find propane leaks, this can be a messy process, especially inside the coach. We recommend using an electronic leak detector instead. These easy-to-use testers provide both audible and visual alarms in the presence of leaks and can detect propane concentrations as low as 50 ppm, making it the perfect tool for RV technicians and RV owners looking for a quick and easy way to detect leaks. Some even come with a flexible gooseneck up to 18 inches long to expand the sensor’s reach even more, perfect for tight and confined spaces like those found in most truck campers