Know how: Propane System Health and Safety

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Liquefied petroleum gas (LPG) is the cooking fuel of choice for most cruisers, but it can kill you if you don’t respect it. Here’s how to keep your propane system healthy and your boat safe

It’s often the things we cannot see that pose the greatest danger on our boats. A recent incident in Wrightsville Beach drove this point home to a world cruiser at the very beginning of his journey. Timothy Wilkinson was lucky to not be killed when his sailboat exploded, reportedly due to a faulty propane installation. The blast blew the cabintop off the boat and sent Timothy to the hospital with second and third-degree burns.

Given the dangers of LPG, why do we continue to use it aboard our boats? In a word, convenience. LPG—either propane or butane—is readily available in most parts of the world at a reasonable cost. A small cylinder of propane can last many weeks and is easy to refill even in remote locations. The truth is, propane can be safe if handled with care and diligence. Usually, problems only occur when safety precautions are ignored or overlooked.

To understand how propane becomes a hazard, envision a bowl filled with dry ice. As the vapor fills the bowl it overflows the edges and down the sides, to the table the bowl is sitting on. Because propane is heavier than air it behaves in much the same manner. A boat hull is like a bowl itself and leaking propane will flow down where it can “puddle” to form a layer of gas waiting for an ignition source. By itself, propane is not explosive—it only becomes a hazard when mixed with oxygen in the right proportions. This is why a small leak can often be more dangerous than a large leak. Also, a small leak is less likely to be noticed until it becomes a hazard.

It is not difficult to set up an ideal propane system; just follow the commonsense Coast Guard recommendations for pleasure boats. For good reason, most insurance companies will require your installation meets these requirements.

PROPANE PROTOCOLS

Propane leaks will most often occur at fittings and connections. This is why the USCG requires that propane not only is stored in a dedicated locker that is sealed from the inside of the vessel, but that most of the connections and fittings be inside such a locker as well. An approved locker is a top-opening container with a vapor-tight lid and a drain that lets water or leaking gases flow directly overboard. Many, but not all, builders provide such a locker.

In lieu of a locker, many sailors secure their propane tanks abovedecks, either to the sternrail or directly on deck. Such an arrangement is acceptable so long as any leaking propane will flow overboard and not into the boat through portlights, hatches, vents or any other opening. Make sure that the tank is oriented correctly—a tank designed to be mounted vertically should not be laid on its side.

You can use either hose or copper tubing for your propane supply line, which should lead directly to the appliance it is supplying, with no valves or connections outside the propane locker. The only exception would be a rubber hose connected to a copper tube to allow movement of a gimbaled stove. If you have more than one appliance aboard, each must have a separate line run from the locker to the appliance. You must never use any T-fittings inside the boat, although these can be installed within the propane locker. All connections must be the flare type, with swaged hose ends. Hose barbs with hose clamps are neither acceptable nor approved by the Coast Guard.

Beyond that, a few things are necessary to properly control the flow of propane from the source. First and foremost is a way to turn off the flow of gas. Of course, the valve on the tank can serve this function, but regulations require a method of turning off the supply at or near the appliance using the propane. This makes sense, should there be a flare-up or other failure that requires rapid shut-off. However, because no connections or valves are allowed inside the boat, the only practical way of doing this is with a remote electric solenoid valve mounted in the propane locker and connected to the tank, with the switch located where it is easily activated from inside the boat.

A regulator is also necessary to reduce the pressurized liquid propane to a gas that can be used by the appliance, and to maintain that pressure as it travels to the appliance where it is being used. It is important to connect a pressure gauge to the tank. This gauge is not there to indicate how much fuel is left, but rather to make it easy to check for leaks on a routine basis (see sidebar).

1. Propane-fueled appliances like this on-demand water heater must be approved for marine use. 2. connections inside the boat are common on European boats. 3. don’t let your propane locker look like this. 4. It’s not just propane hose connections you have to worry about; these wiring connections to the solenoid are all set up to fail. 5. Many cruisers prefer to hang their propane tanks off the sternrail; what such an installation lacks in aesthetics it makes up for in safety

1. Propane-fueled appliances like this on-demand water heater must be approved for marine use. 2. connections inside the boat are common on European boats. 3. don’t let your propane locker look like this. 4. It’s not just propane hose connections you have to worry about; these wiring connections to the solenoid are all set up to fail. 5. Many cruisers prefer to hang their propane tanks off the sternrail; what such an installation lacks in aesthetics it makes up for in safety

KEEP YOUR SYSTEM SAFE

Once your system is in place, make sure the propane locker has a good drain overboard and that the drain is free-flowing. This is easy to do by pouring water into the locker and making sure it drains out quickly. If the drain has a hose going to a through-hull fitting, check to ensure there are no leaks and that the hose is in good condition. Make sure any holes where wires and/or hoses exit the locker are well sealed and as high in the locker as possible. Check the lid gaskets, replacing any that are damaged. Make sure no additional equipment that could damage the connections is stowed in the propane locker. Inspect the propane tank for rust or damage.

Finally, check your stove and any other appliances connected to the propane system. Make sure the stove functions as it should and that it is in good condition. If you have a propane cabin heater, make sure it is approved for marine use and properly ventilated. Download the manufacturer’s manuals for stoves and heaters, and read their guidelines for safety checks. Most camping-type heaters are neither intended for nor approved for marine use and should not be used aboard a boat. Any propane appliances, including instant water heaters, must also be approved for marine use to be safe.

If you haven’t done so already, you should install a carbon monoxide monitor. Most boats do not have good air flow through the cabin and burning a fossil fuel can increase the risk of CO poisoning (see A Faulty Heater Nearly Leads to Tragedy, January 2016). I would also recommend installing a gas detector that sounds an alarm if it senses propane. Turn the gas off at the tank after every use. Although propane is not 100 percent risk-free, if you take care and carry out regular systems inspections, it can be as safe as any other fuel used on your boat. 

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Checking for Leaks

To check for leaks in your propane system, open both the tank valve and the remote solenoid valve, but leave the appliance valves closed. Then close the tank valve while leaving the solenoid open. After about 10 minutes check the gauge to see if there was a pressure drop.

A slight drop is to be expected, but anything more than about 10 percent indicates you should check for leaks. Obviously, you should never use a flame to do this. Although portable leak detectors have dropped in price, I still like using soapy water to do the job. A bit of dish soap mixed with water either sprayed or brushed on a suspect fitting will quickly reveal any problems, with bubbles forming around the fitting. Carefully check all connections and if you find any leaks, fix them and retest the fitting.

Marine surveyor Wayne Canning lives on his Irwin 40, Vayu, in Ft. Myers, Florida. His book Restoring Fiberglass Boats is due out this summer.

Photos by Peter Nielsen and Wayne Canning 

July 2017

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