Propane Leak Detector: What to Buy and Where It Goes
If you can smell propane now, leave first. Get out, leave doors as they are, touch no switches and light nothing, and call your propane supplier's emergency line or the fire service from outside. A detector is for the leak nobody has noticed yet.
Propane is sold with an odorant added so that a leak smells of rotten eggs. That odorant is the reason most leaks are found by people rather than devices, and it is also why a detector earns its place: the smell fails you when you are asleep, when a leak is slow, or when the odorant has faded in an old tank.
Propane pools low, and that changes everything
This is the one fact that decides whether your detector works. Propane is heavier than air. It sinks, runs along the floor and collects in the lowest space available: a basement, a pit under a caravan, a boat bilge, the footwell of a cupboard.
So a propane detector is mounted near the floor, typically within a foot or so of it, and the manual for your model gives the exact height it was tested at. A combination alarm mounted at head height in a house that runs on propane is a working alarm that will never meet the gas.
Natural gas behaves the opposite way: lighter than air, it collects at the ceiling. If you are on mains gas, the same product goes high instead. Our gas leak detector collection covers the products that handle both and how they differ.
Where propane leaks actually happen
- At the connection, far more often than in the tank or the line: regulator fittings, hose ends, the point where a cylinder couples to an appliance.
- In enclosed low spaces where a small, slow leak has somewhere to gather rather than disperse.
- In caravans, boats and cabins, where a cylinder sits close to a living space and the whole structure is small enough for a modest leak to matter.
A fixed alarm watches a room. A handheld sniffer walks the pipe and tells you which fitting is leaking. They answer different questions, and the collection above separates them.
Detector, not a substitute for a service
A detector does not stop a leak, and it is not a replacement for having gas appliances serviced by somebody qualified. What it does is turn the failure mode from "nobody noticed" into "something noticed at three in the morning". That is worth the price of the unit on its own.
Two more things worth knowing before buying:
- Many home units are combination CO and combustible gas alarms. That is usually a sensible buy, because the two hazards share a source: fuel-burning appliances. It also forces the mounting decision, since the gas decides the height.
- Sealed and plug-in units still expire. The sensor has a service life whether or not anything ever triggered it, and how long alarms last applies to combination units too.
If the alarm sounds
Leave, then call from outside. Do not open windows first, do not hunt for the leak with a lighter, and do not switch anything on or off on the way out, including the light. Once the supplier or the fire service has cleared the property, the fitting that leaked is a job for a qualified engineer rather than a tightening with a spanner.