10 Tips for choosing a Gas Alarm
1. What is your power supply? A gas alarm will require a fused electrical power supply and although some 24V gas alarms are available, the majority of products are 12V. So if you have a 24V power system on board, make sure you check the product specification before you purchase an alarm.
2. Do you have sufficient power for the alarm to be left on? You may want to consider having the gas alarm wired so it is continually on, even when the boat is unattended. This has the advantage of alerting you to a problem as soon as you return to the boat. The downside is that the alarm will continuously draw electrical power and you may be left with flat batteries if you do not have a shore power connection or another means of keeping the battery levels topped up.
It is worth comparing the power consumption of the various gas alarm models you may be considering.
3. An alternative to save battery power. Another option would be to have the alarm wired so it is turned on every time you switch on the master battery. This saves battery power, but there is a risk that the battery switch could cause a spark and ignite any LPG that has leaked while the gas alarm was off. This could usually be avoided if the gas cylinder is always turned off at the main valve whenever you leave the boat and if the gas cylinder is stored in a properly-drained gas locker.
4. Where to locate the sensors. There are various single or multi-sensor gas alarms now available. As most sailors and boat operators know, LPG is heavier than air and will collect in the bilges or in the bottom of a locker, so it makes sense to fit a sensor in any area of the boat where gas could collect.
Installing a sensor under the main gas locker or in any space where there is a gas pipe joint is generally recommended. The most common areas for leaks are those that are subject to regular wear, such as flexible gas hose connections and around regulator valves.
5. Why use a multi-sensor alarm? Boats generally have more than one place where there is gas pipe join, so a multi-sensor gas alarm should really be installed on most vessels.
David Stoppard, a CORGI and Gas-Safe registered engineer at Marine Systems Engineering, advises, "The ideal place to install a sensor is at the lowest point where gas is likely to collect. However the sensor should not be installed directly below the cooker if you are to avoid false alarms, or next to a hatch, port hole or extractor fan where ventilation could hide a true leak."
"Gas sensors should also not be installed in areas where dirt and dust can easily clog the sensor or anywhere they are likely to get wet because the majority of sensors are not waterproof."
6. Will the product have sufficient cable for your boat? Most gas alarm sensors are supplied with around 3-5m of cable. However some products will not allow you to extend the cable because they use non-standard connectors or because the design of the sensor is distance-sensitive. Check to see if the length of cable supplied with the alarm is long enough for installation on your vessel.
7. Where should you locate the control panel? There is no benefit to installing the control panel at the chart table (often the preferred location!) if the gas sensors cannot reach the places you need them. And the gas alarm display should not be hidden away in a locker or where no-one will see it. When a gas alarm sounds, even the most novice crew member must be able to quickly identify the source of the sound and understand what it means to act accordingly.
8. How to use the gas alarm. A gas alarm will not stop a gas leak, but it will alert you to its presence. Fitting a gas alarm should not be used as a substitute for good housekeeping or for ensuring that you have a safe gas system on board. The gas should always be turned off at the main cylinder valve whenever it is not in use.
9. Should you have your gas system inspected? Having the complete gas system inspected by a CORGI/GAS-SAFE registered engineer will give you greater peace of mind - and a Gas Safety Certificate may even help to reduce your insurance premium.
10. Where can I find a registered gas installer?
For a list of marine gas installers around the UK see: Marine Gas Installers