Maintaining your Propane system

New ArticleMaintaining your Propane system.
As Published in Cruising World, July 2011

By Capt. Wayne Canning, AMS
Most modern cruisers are equipped with propane as their primary cooking fuel. Northern sailors often use it for heating as well. It is perhaps one of the best cooking and heating fuels as it is readily available and clean burning. Despite its convenience propane does carry some hazards and although not very common propane explosions and fires can be tragic and devastating.
I am often struck by how little effort is put into maintaining propane systems considering the danger should a fault develop. The problem is not lack of concern or effort on the part of the boat owner but rather lack of knowledge about how to maintain their systems and where to look for problems. With this in mind, having an understanding of the systems and how to maintain them is important for any boat owner using propane.
Understanding a bit about propane will help you understand why systems are designed the way they are and how to avoid problems. Propane is a hydrocarbon gas that becomes a liquid under pressure, when the pressure is released the liquid becomes a gas once again. This makes the storage and transportation of propane relatively easy. Propane is heavier than air and will settle into a bilge just like gasoline fumes do. If you have ever watched the vapors from dry ice flow over the sides of a container you have a pretty good idea how leaking propane will flow. Of course like gasoline propane can be very explosive.
Most systems are relatively simple in design consisting of a propane locker, propane tank or tanks, a gauge, a regulator, a solenoid valve and the supply line consisting of either propane rated hose or copper tube. Let’s look at each part individually and then look at how they all work together.
A propane locker is designed to prevent any leaking propane from entering the boat interior. The USCG requires lockers to be vapor tight to the inside of the boat and have a top opening lid with a gasket and latch. Lockers must have a drain at the bottom that will vent to the outside of the boat above the waterline. This drain must be a downhill run with no loops to trap water. Hoses and wires that exit the locker need to be sealed vapor tight. The propane locker tends to be the weak point in any installation as they are often not properly designed or built. Do not assume because the builder installed the locker it is correct. Lockers mounted on the deck or rails need to meet the same requirements as well.
The first thing that goes into the lockers is the propane tanks. Tanks come in all shapes and sizes but the common sizes found on cruising boats are the 10 and 20 pound tanks and very often one or two of the small 1lb camp stove bottles for a grill. All propane tanks must be stowed in the propane locker even the smaller camp stove bottles.
Connected to the tank is the regulator and pressure gauge. The gauge is on the high pressure or tanks side of the regulator and is used for leak detection. Contrary to what some people think the gauge will not indicate how much fuel you have left in the tank. The regulator reduces the high tank pressure to a lower working pressure for your appliances. The regulator and fittings must remain in the propane locker with no connections outside the locker.
After the regulator is the solenoid valve. This is an electric valve that is remotely operated from a switch near the appliance. The solenoid valve is normally closed meaning it will not open until power is supplied. This is your primary safety device and should be left in an off position unless you are using your stove or heater. Although not required there should be a red light located near the switch to indicate when the power is on and the valve open. It makes sense to locate the switch separate from other switches and indicator lights so that it can readily be sighted if left on accidentally.
Connected to the solenoid is the supply line to feed the appliances. If you have more than one appliance, say a stove and heater each unit should have its own supply line originating within the propane locker. The supply line can be either rubber hose with permanently attached end fittings or copper tubing with flare fittings. The supply line must be a continuous run from the propane locker to the appliance. The only place a connection is allowed is when using copper tube with a gimbaled stove. In that case a section of flexible hose needs to be used to connect the copper tube to the stove.
When inspecting your propane system for potential problems it is best to star at the locker. Make sure the drain hose is open and does not have any traps that will hold water. Check the locker itself for cracks or gaps in any caulking. Check the seals around the wires and hoses where they exit the locker. Also check the hatch gasket and latch to ensure they are in good condition. Next check the tanks for rust or corrosion particularly around the bottoms. Inspect the valves and fittings at the top of the tanks. Check the regulator, gauge, solenoid, and fittings for corrosion or damage. Inspect the wiring to the solenoid making sure any connections are properly done and in good condition.
If everything looks good it is time to start following the supply line through the boat. It is important to inspect the whole run. Problem areas often develop in hard places to see such as where the line passes through bulkheads. With copper tube you want to look for corrosion and that telltale greenish flaking on the surface. Copper tubing can look great for most of its run but have one small area of corrosion that can result in a leak. With rubber hose you want to be looking for signs of dry rot, those small cracks that develop. For either type of line make sure it is well supported the full run and that it is not pinched or chafing where it goes through any bulkheads. Also make sure no wires are tied to it. If you have a gimbaled stove make sure the hose will not rub on anything for the full swing of the stove. Because this section of hose is moving you want to inspect it carefully for signs of wear. Check the tightness of all fittings by using a wrench. If you are at all not sure about the condition of your gas line and it is more than ten years old it is best to just replace it.
Once this visual inspection is complete and any repairs are made it is time to do a leak down test. Before you start turn off any electrical power and open the boat up for ventilation. With your appliance valves closed and the solenoid valve off open the cylinder valve fully. Note the location of the needle on the pressure gauge. You may want to use a piece of tape to mark the needle location. Fully close the tank valve and wait at least five to ten minutes for any drop in pressure. The needle should not have dropped more than few pounds. If no pressure drop was noted, repeat this test with the solenoid valve open and the appliance valves closed. Wait at least five to ten minutes and note any drop in pressure. If the pressure drops more than a few pounds and continues to drop in either of these testes you need to check for leaks.
When checking for leaks use a small spray bottle with soapy water in it. With the tank valve open, the solenoid valve open and the appliance valves closed, spray each fitting with soapy water. Start at the tank end and work your way through till you get to the appliance. Spray areas where the hose passes through bulkheads as well. Leave the soapy water on for five to ten minutes with the pressure on. Look for small foaming bubbles. If you note any leaks turn off the valve at the tank and bleed off line pressure before starting repairs. Once you have repaired any leaks run the test again. If you do not find any leaks and you are still losing pressure it is possible that your appliance is leaking. If this is the case it may be best to have a service technician check it out.
Maintaining a propane system is relatively easy and will provide you with piece of mind. I recommend doing a complete system check every time you refill your tanks. Try to make it a habit to do a leak down test before using your stove or heater and always turn off your propane at the tank when you leave your boat unattended. Used carefully propane is a great fuel to have onboard, just take the time to make sure it stays a safe fuel.