The problem
A smoke detector is a device for confirming that a fire has started. That is a genuinely valuable thing and every plant should have them — but it is a late signal by design, and the interval it gives you is the interval between a fire existing and a fire spreading.
Most industrial fires do not begin with flame. They begin with a smoulder: a bearing running hot, an overloaded cable, a pile of oily rags, a motor winding failing. That phase can run for minutes or hours, and it emits combustible gas, carbon monoxide and a degrading air quality long before it emits visible smoke. Nothing in a standard installation is looking at any of that.
Which channels see it
Detection here is not one sensor reporting a number. It is several channels read at the same instant, where what one channel does NOT do is often as informative as what another does.
- Surface temperature — A contact probe on the equipment itself. A hot spot shows here long before the room warms.
- Combustible gas — Rises during a smoulder as material begins to break down.
- Carbon monoxide — The characteristic product of incomplete combustion — the defining marker of a smoulder rather than a leak.
- Air quality — Degrades steadily through the smouldering phase.
- Flame — An infrared channel. It is the confirmation of open ignition, and its ABSENCE is what identifies the phase as a smoulder.
- Ambient temperature — Lags surface temperature. The gap between the two is itself the signal.
How it is detected
The smouldering-combustion signature is a specific shape: gas and CO rising, air quality degrading, surface temperature climbing ahead of ambient — and no flame signature. That last term is not a missing piece of evidence; it is what distinguishes a smoulder from an open fire and determines which response is appropriate.
Surface temperature is measured with a contact probe rather than inferred from the air, which is what makes it early. A bearing housing at ninety degrees is a fact about the bearing available now; the room reaching an alarming ambient temperature is that same fact, an hour later and much larger.
When the signature is recognised the node escalates its own recording rate from one vector every ten seconds to one every second, bounded at five minutes. So the record of the event is dense exactly where it matters, and cheap the rest of the time.
The infrared flame channel runs alongside all of this as an independent fast path. Open flame is not something to reason about with a rolling window.
What an operator gets
The output is meant to be actionable by somebody on shift, not interpreted by an engineer afterwards.
- A warning during the smouldering phase, in the window where a fire extinguisher is still the right tool.
- The location: which node, and with the rotating head fitted, a bearing to the source from that node.
- A forecast of which named assets the event reaches, and when — a solvent store forty seconds away is a different response from one twelve minutes away.
- A second-by-second replay of the episode with the system's own reasoning attached, for the incident report and the insurer.
