3.1 It is essential that all installations are gas tight and that competent engineers have carried out the installation, so it is recommended that a CORGI registered engineer is used. All appliances must be fitted in accordance with the manufacturers specifications and the ventilation requirements adequate to ensure the flow of fresh air. The gas supply should be turned off at the cylinder whenever there is no requirement for gas including overnight.
3.2 These days there are a number of devices which can safeguard boats against accidents. Many of these are available from Calor Gas Dealers:-
3.2.1 The "Alde 4071-905" gas Leak Detector (bubbler device) is plumbed into the gas supply immediately downstream from the regulator (see Best Practice Installation). This shows slightest leak in the yacht's gas system and provides the best way of checking daily that the entire gas system is gas tight. Note: the limited gas throughput of the 4071-905 makes it suitable for use with a cooker and fridge, but not with a water heater.
3.2.2 Electronic gas leak detectors (available from chandlers) give an audible signal and/or visual signal of gas before it becomes dangerous. They will automatically shut off the gas supply if fitted with the appropriate motorised valve. They can also automatically start extraction fans to evacuate gas from the bilges. 12 volt and 240 volt models are available.
3.3 When in harbour the surest way of turning off the gas supply is at the cylinder, rather than just on the appliance. However, in dirty weather this may be inconvenient, in which case a remote shut-off switch is a real asset. A shut-off valve kit comprises a 12 volt switch in the cabin and a motorised valve plumbed into the gas system immediately down-stream from the regulator. It allows the crew to switch the gas off (or on) from inside the boat and avoid possible danger from appliances which may have their knobs knocked or pushed inadvertently. This type of remote shut-off valve is not designed to withstand liquid gas - see para 3.6.
3.4 Nowadays, many appliances are protected by automatic safety devices which turn them off if the ventilation becomes inadequate (see makes appliance literature for specification). In addition, these devices also automatically shut off the gas supply if for any reason the appliance's flame should be accidentally blown out by a draught etc, protecting the crew against Carbon Monoxide poisoning and/or explosion due to an escape of gas being ignited. However, most cookers and water heaters have yet to be designed with these safety devices and therefore, under no circumstances should cookers be used for space heating purposes or water heaters operated without adequate ventilation.
3.5 Devices to detect carbon-monoxide are now available. Carbon-monoxide (which is invisible, tasteless, deadly poisonous and is the same density as air) is produced by any gas-burning appliance when there is inadequate ventilation, i.e. if all the hatches are battened down and a cooker oven is lit to heat the cabin, then it is likely that before long carbon-monoxide will be produced as the ventilation becomes inadequate. (The oxygen level will decrease as carbon-monoxide increases which will result in the production of carbon-monoxide). The first effect of carbon-monoxide is to remove the will of the crew to take action. They fall asleep and die - possibly in a matter of hours - before the gas appliance is fully starved of oxygen and goes out!
So take care. Ensure that you have adequate ventilation, and consider fitting a carbon-monoxide detector. 12v, 240v and portable 9v models are available.
3.6 If sailing in rough weather make absolutely certain that the gas is turned off at the cylinder and make sure that the cylinder itself is securely fixed in place with a metal bracket or is lashed down firmly. Shock cord is generally inadequate. The danger to be guarded against is that of the cylinder being thrown on its side or inverted in which case liquid gas may well enter and pass through the regulator. This can cause a seventy-fold increase in pressure in what normally should be the low pressure section of the installation. Taps may leak and highly dangerous flare ups may occur.
TURN OFF THE GAS AT THE CYLINDER TO BE SAFE
3.7 It should be stressed that gas appliances are safe provided they are correctly installed and operated for the use they were intended.
Most importantly, in order to maintain the safety and efficiency of the system, it should be checked and serviced annually by a competetent person.
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