An emergency warning light labelled 'gas'
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How does a boat gas alarm work?

Installing a boat gas alarm is an important safety measure to detect LPG leaks and raise the alarm, both for the safety of those aboard, and to protect against damage or loss of the vessel.

A boat gas alarm has several components. These include one or more LPG sensors, which are connected via cables to the alarm unit.

The LPG detectors are placed in appropriate locations around the vessel: typically low down where leaking LPG will settle, but above any level that is likely to get wet.

In the presence of LPG, the electrical resistance inside the sensor will change, leading to an output current that is carried back to the alarm base unit.

When a current is detected, the alarm is triggered. This can have several different effects to quickly protect the vessel and anybody aboard:

  • An audible alert tone is sounded to make occupants aware of the risk.
  • An LED indicator on the alarm panel shows which sensor has activated.
  • A solenoid valve automatically shuts off the supply of LPG to the leak.

Using a solenoid valve means that as soon as a potential leak is detected, the gas supply can be stopped, allowing safe investigation of the problem and/or evacuation of the vessel without putting people at risk.

One channel or two?

A Twin Channel Gas Alarm offers two separate sensor channels, so that you can detect LPG in two different areas of your boat.

This can be beneficial for larger vessels, where a single sensor might not provide enough coverage, but can also be useful on smaller boats for more specific detection.

For example, if you routinely use LPG in more than one part of your vessel, installing a sensor close to each point of usage ensures any leak is detected as soon as possible.

Twin Channel Gas Alarms include independent test functions, so you can verify each channel is working in its own right.

Replacement boat gas sensors

It is a good idea to install replacement boat gas sensors at least every two years. Replacement LPG sensors cost from around £25 and are relatively easy to swap out.

Early alarms (pre-2012) may need the sensor housing to be replaced too, so make sure to order a replacement LPG sensor with block connector and housing if necessary.

After 2012, sensor housings were made swappable, so you should be able to replace the LPG sensor without disconnecting the housing from its installed position.

Finally, if you want to change the position of the LPG sensor aboard your craft, choose a new sensor with housing and 3.5m cable, and install according to the directions for a new sensor or alarm.

Need any help?

If you’re not sure how to go about installing or replacing an LPG gas alarm, or you have an existing system installed and need some help to understand how it operates, please get in touch.

Envin Scientific supply Pilot Gas Alarms, Twin Channel Gas Alarms, replacement LPG sensors and replacement solenoid valves in the Envin Shop, so you can order direct for quick delivery of items in stock.