Flame detector

What a flame detector actually is

A flame detector is an optical instrument. It looks for the radiation signature a flame produces and ignores everything else it can. Three families are common.

Ultraviolet detectors watch a narrow solar blind band and respond very quickly, but they are the family most easily fooled by arc welding, lightning and some lamps. Infrared detectors typically watch the carbon dioxide emission band produced by hydrocarbon combustion, often with flicker frequency discrimination so a steady hot object does not read as fire. Combined UV and IR and multi spectrum infrared designs require agreement between bands before declaring an alarm, which is how modern units get long detection distances with tolerable false alarm performance.

Two things follow from it being optical. It needs an unobstructed line of sight, and it is blind to a smouldering fire that produces plenty of smoke and no flame. A flame detector is not a general purpose replacement for a smoke detector.

Which document governs it in Canada

The Canadian certification document is ULC/ORD-C386, Flame Detectors, 2nd edition, published 31 August 2015. It is an Other Recognized Document, a category ULC uses where no National Standard of Canada exists for a product, so it does not carry the CAN prefix that S524 or S529 do. UL Canada's certification bulletin for it states that it covers the design, construction and performance of flame detectors rated at 300 V or less, that it was written in alignment with the smoke detector standard S529, and that detectors meeting it are intended to be installed in accordance with CAN/ULC-S524 and CSA C22.1, the Canadian Electrical Code, Part I.

That matters on a real job: flame detectors often sit in classified hazardous locations, so the wiring method is driven by the electrical code as much as by the fire alarm standard. See CEC Section 32 for the fire alarm circuit rules and fire alarm cable in Canada for what the two documents require together. No Canadian building code table names it: it reaches your job through the listing on the device. The general distinction between a published edition and one a code designates is set out in the edition tracker.

When you would actually find one

No Ontario Building Code article requires a flame detector by name. The Code defines a fire detector broadly and names heat and smoke detectors as its examples, so whether a flame detector satisfies a fire detector requirement in a particular room is a question for the designer and the authority having jurisdiction, not one this page can settle from the definition. In practice flame detectors turn up because a process hazard, an insurer or a specification asked for them, and they are usually additional to the code required detection rather than a substitute for it.

How it behaves in the field

• Field of view is a cone, and the rating is a distance to a defined test fire. Move the unit, tilt it, or change the size of fire you care about, and the coverage changes. Aiming is part of the installation, not an afterthought.
• The window is the weak point. Dust, oil film, paint overspray and ice all cut sensitivity without any obvious symptom, which is why most units run an optical path self test and report trouble when the window degrades.
• False sources are physical, not electrical. Arc welding, hot exhaust, direct or reflected sunlight, halogen work lights and moving machinery that chops a light source at flame like frequencies.
• Testing needs the manufacturer's method. A calibrated test lamp or an approved test fire, at the rated distance and within the field of view. A lighter held under the lens is not a test.

Where it sits next to the other devices

A heat detector waits for the fire to warm the ceiling. A smoke detector waits for particles to reach it. A flame detector responds in the time it takes light to cross the room, which is why it is chosen where the credible fire is a pool or jet of burning fuel and seconds decide the outcome. In a building with a mixed hazard you will often see all three, on different zones, doing different jobs.

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Fire Alarm Academy provides educational content only. It does not confer any certification, licence or credential, and it is not affiliated with, endorsed by, or accredited by the Canadian Fire Alarm Association, the Electrical Contractors Association of Ontario, ULC Standards, UL Standards and Engagement, CSA Group, the Electrical Safety Authority, any authority having jurisdiction, or any manufacturer. Always work from the edition of any standard adopted by your authority having jurisdiction.