Liquefied Petroleum Gas (LPG) is frequently used as fuel for stoves on board boats. LPG is however potentially hazardous if the gas is not stored suitably or if the cooker and/or pipe work are badly maintained or damaged.
In the UK, LPG is available as propane or butane. The two types of LPG have slightly different properties. Butane has a lower operating pressure of 28 millibars but a higher calorific value and therefore a higher flame temperature. It is more commonly used in the UK as fuel for stoves on boats. Propane operates at a pressure of 37 millibars and works better in colder climates than butane. Operating pressures may be different elsewhere in the world.
Gas safety considerations
Gas is more dense than air, so in the case of a leak, it will make its way to the lowest point i.e. the bilges where it will stay until the boat is aired to clear it or something ignites it, which can result in a significant explosion.
Although LPG is potentially hazardous, it can be used quite safely if the equipment is properly installed, well maintained, regularly inspected for damage and used carefully.
Gas bottles should be stored upright in a dedicated locker which drains overboard (to help prevent gas ending up in the bilges). The drain should be checked regularly for blockages, for example by squirting a hose pipe down the drain.
For boats which were not manufactured with a dedicated gas locker, finding appropriate stowage for the gas bottles can be difficult. The simplest option may be to secure the bottle on deck. However this needs to be done carefully to prevent accidental damage and should not be in a position which would allow leaking gas to enter the interior of the vessel i.e. located too close to hatches.
Most boats will also carry a spare cylinder which should be given the same consideration as the "in use" cylinder. Although the spare cylinder is less likely to leak, it is not impossible for it to do so especially if it is not securely positioned and protected from damage.
Gas pipe and hose
Pipes and hose should be regularly inspected for wear and tear. Gas hose is marked with the date of manufacture and has a life expectancy of 5 – 10 years, depending on the environment in is in. Don’t fit it and forget it!
Particular attention should be paid to vulnerable hose, such as where the cooker gimbals. The area behind the stove should be covered with a sheet of metal to prevent accidental damage to the vessel’s hull.
Gas safety devices
Flame supervision devices (which shut the gas off if the flame accidentally goes out) have been available since the early 1990s and are now routinely fitted to marine equipment. These have significantly improved gas safety on board.
Many boat owners now fit their boat with a gas alarm. The sensor for the alarm is positioned where gas is most likely to collect if there is a leak and the alarm goes off if it senses gas. Unfortunately, gas alarms have been prone to false alarms which all too often lead to the alarm sounding not being taken seriously – a bit like burnt toast setting off your home smoke alarm.
There are now modern gadgets available which can automatically shut off the gas when it is not in use and others which monitor the installation and indicate if there is a leak. A bubbler device, for example, is plumbed into the gas system and indicates the slightest leak, although as this is plumbed in directly downstream of the regulator, on many boats this may not be a particularly convenient location for regular inspection.
Using gas safely
Every boat should have a gas routine. What this is will depend on the design of the boat, the layout of its gas installation and the skipper. Ultimately, the safest option is for the gas to be turned off at the bottle whenever it is not in use and some skippers will ask that the flame is extinguished by turning the bottle off to ensure no gas remains in the pipe.
On many boats, the location and accessibility of the gas locker may make turning the gas off at the bottle an unattractive option. Many boats are fitted with a gas tap near the galley, which is often more accessible and many skippers opt to use this secondary tap. This option will prevent gas leaking if the stove (or other device supplied by the bottle) fails, but will not make a difference if the installation fails between the secondary shut off and the bottle. On some boats the gas may simply be left on and the cooker relied on to retain the gas, just as you do at home. The risk increases the further away from the bottle the gas is isolated.
Skippers are likely to take flame supervision devices and gas alarms (devices which sound if the sensor – which is located where gas is likely to accumulate in the event of a leak – e.g. the bilges) into consideration when setting the gas routine, which should take into consideration the weak points in the installation (i.e. where a leak is more likely e.g. joins and flexible hose). Everyone on board should know and follow the routine when using the gas.
In rough weather the gas should be turned off at the bottle and the bottle secured to ensure it cannot end up on its side or upside down which would allow gas to enter into the regulator at a dangerously high pressure; this could lead to taps leaking or dangerous flare-ups.
Should a gas leak be suspected:
- DO NOT SMOKE
- Shut the gas off at the bottle
- If in port, get everyone off the boat
- Lift the floor boards, open all the hatches and air the boat
It is commonly believed that manually pumping the bilges will clear gas. This alone will not dispel the gas, although it may help to create an air flow.
Never test to see if there is a gas leak with a naked flame, if there is a leak there is also a significant risk you will cause an explosion! An electrical spark will do the same, so do not operate lights or electrical equipment, including the electronic bilge pump, if a leak is suspected.
Installation and maintenance
The Recreational Craft Directive (RCD) specifies that LPG installations must conform to ISO standard 10239 LPG Gas Systems for all recreational craft of less than 24m LOA.
There is no requirement for private boat owners to maintain and repair their LPG system on a regular basis. If the vessel is operated on inland waterways and requires a Boat Safety Scheme (BSS) certificate it must additionally comply with the BSS requirements. This does not require that a Gas Safe Register engineer carries out the work as the BSS does not stipulate how this compliance is achieved.
For other private pleasure craft, where the BSS does not apply, there is still no general legal requirement in UK waters to have the gas installation fitted, repaired or inspected by a qualified engineer (unless there is someone living or working on board or local regulations may apply). A Gas Safe Register engineer will, however, know the correct materials and methods to use, to ensure that the work is completed safely.
The RYA strongly recommends that gas systems are checked regularly to ensure that any potential problems are spotted at the earliest opportunity. You may choose to do this yourself, looking for kinks or wear in the hose, making sure none of the clips are coming loose etc. or owners may opt to have their marine LPG installation inspected by a suitably qualified person, such as an engineer listed on the Gas Safe Register - as they do with gas boilers in the home. The gas industry recommendation for marine installations is for this to be done annually.
If you prefer to trust the trained eyes of a professional then at www.gassaferegister.co.uk a search based on postcode will help you to find the nearest registered engineer.
The silent killer carbon monoxide should not be forgotten or underestimated. Incomplete combustion of fossil fuels can produce carbon monoxide (CO). Appliance failure or damage, poor installation or lack of maintenance could all lead to bad combustion of the LPG, which coupled with poor ventilation can result in CO poisoning which may kill.
Regular inspection, together with a gas alarm, a CO detector and safe operation will significantly reduce the risks associated with having gas on board.
One of the largest suppliers of gas in the UK is Calor - useful advice is available on their web-site on the availability of gas supplies overseas and changing between propane and butane.
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