Smoke Detector

medium 260 models total

A ship's smoke detector is chosen by fire behaviour, not brand: optical heads catch smouldering, particle-heavy fires early, ionisation heads react faster to open flame with little smoke, and picking the wrong type for a space leaves a real blind spot in the detection system.

Read more — Smoke Detector explained ▾

What distinguishes this detector type

Point-type smoke detectors used on board fall into two working principles. Optical (photoelectric) detectors shine an infrared beam across a sensing chamber and measure light scattered by smoke particles; they respond well to the dense, visible smoke typical of smouldering cable insulation, upholstery or slow-burning solids. Ionisation detectors use a small radioactive source to ionise air in the chamber and measure the drop in current when smoke particles interfere with that ionised flow; they respond faster to the fine, largely invisible particles thrown off by fast-flaming fires with little visible smoke, such as burning fuel or paper. Multi-criteria detectors combine a smoke sensor with a heat or CO sensor and vote between them to cut false alarms, at the cost of a slower response in a genuine fast fire.

Optical smoke detector, cross-section — Cross-section of a ceiling-mounted optical smoke detector, showing the labyrinth sensing chamber with its LED light source and offset photodiode receiver that picks up scattered light when smoke enters through the vents and insect screen, plus the alarm circuit board and status indicator LED.

Main components

Sensing chamber

The optical or ionisation element itself, protected by an insect screen and a light trap or ionisation chamber housing. This is the part that ages: dust and salt-laden air gradually raise the baseline signal until the head drifts into false alarm territory.

Detector base and loop wiring

Plugs into a fixed base wired into an addressable or conventional loop back to the fire panel. Addressable bases carry an individual address so the panel reports the exact detector, not just the zone.

Fire panel interface

Processes the analogue signal, applies drift compensation and raises alarm, pre-alarm or fault at the bridge panel and any repeater panels.

Selection and placement

Type selection follows the fire risk of the space, not a fixed rule for the whole ship:

Machinery spaces and areas with oil mist: heat detectors or multi-criteria units, since smoke detectors alone false-alarm on normal engine room haze.
Accommodation, control rooms, cable trunks: optical smoke detectors are the default.
Galleys and spaces with cooking fumes or steam: heat detectors or specially rated smoke detectors to avoid nuisance alarms.
Coverage area per detector, ceiling height and beam obstructions all affect spacing and must follow the fire detection system's approved layout drawing, not a generic ceiling grid.

Regulations and class

SOLAS Chapter II-2 requires fixed fire detection and alarm systems in specified spaces depending on ship type, and the detectors themselves must meet the applicable IMO performance standard for shipborne fire detection equipment. Class rules require the system to be tested and the individual detector heads to be functionally tested at survey intervals set by the classification society, with sensitivity drift checked against the manufacturer's data. A detector that has drifted out of its calibrated window is treated as a fault, not left in service on the assumption it "still works".

Typical faults

Fault	Cause	Consequence
Nuisance alarms	Dust or salt build-up in the chamber, insect ingress, wrong type for the space	Crew starts isolating or ignoring zones, defeating the system's purpose
No alarm on test	Corroded base contacts, broken loop wiring, detector not seated	Real fire in that space goes undetected until it is visible or smelt
Ground fault on loop	Chafed cable at a bulkhead penetration, moisture ingress in a junction box	Panel may isolate part of the loop, dropping several detectors at once
Sensitivity drift flagged by panel	Ageing sensing element, contamination	Detector due for cleaning or replacement before it fails outright

What to look for in a supplier

Type approval certificate matching the specific detector model, not just the product family.
Compatibility confirmed with the existing fire panel's protocol - addressable loops are not interchangeable between panel manufacturers.
Traceable batch and manufacture date, since sensing elements have a service life independent of whether they have triggered an alarm.
Availability of the matching base, since heads and bases from different ranges of the same maker are not always compatible.

When a detector keeps false-alarming, replace or clean it rather than isolating the zone on the panel - an isolated zone is a zone with no fire protection at all, and it is easy to forget it was ever isolated.

Smoke detector. Photo: Tumi-1983, CC BY-SA 3.0, via Wikimedia Commons

Inspector Mode Show All 260 total

2 manufacturers · 1–100 of 260 models

Hochiki Marine

67 ✓ 58 verified

SOC-24V ✓ verified

Application

Conventional Photoelectric Smoke Detector

Common Failures & Inspection Points

Area: Detector Optical Window Obstruction
Check: Visually inspect detector lens and chamber for dust, insect contamination, or corrosion buildup. Clean or replace detector if optical transmission is compromised (use magnifying glass for small particulates).
Area: Sensitivity Drift and Calibration
Check: Perform semi-annual sensitivity testing using manufacturer-approved calibration tools (e.g., NSTT-C for SIJ-24 series). Verify detector responds within listed sensitivity range (typically 25%-70% obscuration for photoelectric). Replace if sensitivity cannot be recalibrated.
Area: Installation Mounting and Alignment
Check: Verify detectors are properly seated in bases (confirm clockwise twist-lock engagement). For beam detectors, confirm alignment within reflector center using motorized alignment verification. Check mounting hardware security and absence of vibration-induced looseness.
Area: Electrical Continuity and Base Contact
Check: Verify electrical connections at detector base and wiring terminals. Test continuity to control panel. For conventional detectors, confirm 24VDC supply voltage at detector head. For addressable detectors, test SCI loop continuity and polling response.
Area: Environmental Interference and False Alarms
Check: Inspect for sources of nuisance triggers: proximity to HVAC ducts, direct sunlight on beam detectors, steam/condensation sources near smoke detectors, or electromagnetic interference near addressable loops. Reposition detectors or install optical filters as needed per EN54 standards.

Typ-universelle Inspektionspunkte fuer Fire Detection Systems (verifiziert, 2026-06).