FS24X Plus

Real Fires Are Dirty

This is the argument the whole detector is built on, and it addresses a weakness in conventional infrared detection that most datasheets don’t mention.

Standard multi spectrum infrared detectors watch narrow bands, typically the emission from hot carbon dioxide around 4.3 microns. That works well on a clean test fire. Most real fires aren’t clean. They’re sooty and smoky, full of carbon based particles that absorb and scatter exactly the narrow band signal the detector depends on.

Honeywell’s answer is to widen the view. WideBand IR uses solid state, wide band sensors, so the detector isn’t relying on a single thin slice of the spectrum getting through. Honeywell says the FS24X Plus can see through rain, fog and smoke better than other technologies, so it keeps detecting in poor visibility.

Hydrogen Without a Second Detector

The FS24X Plus detects hydrocarbon and hydrogen fires from the same unit.

That’s worth noting against the alternatives. Most infrared detection needs a dedicated hydrogen model, because hydrogen burns to water vapour rather than carbon dioxide, and produces nothing on the usual bands. The FS24X Plus covers both.

Honeywell’s tested fuels include n-heptane, IPA, methane, butane, propane, ethanol, methanol, hydrogen, diesel, kerosene and JP-4. For a facility handling hydrogen alongside hydrocarbons, that removes a specification decision and keeps the spares holding to one detector type.

Range, Sensitivity and Field of View

Sensitivity is set in Flame Manager, with four levels for a 0.1 square metre n-heptane fire: low (15 m), medium (30 m), high (45 m) and very high (60 m). Response is typically 5 seconds, with a maximum of 10 seconds (FM witnessed).

The cone of vision is 90° for all standard mounts. Indoors, at very high sensitivity and 50% of the on axis distance, it can extend to 120°.

Detection distance is only half a coverage calculation. Field of view is the other half. A detector reaching further with a narrower cone can need more units than a shorter one with a wider cone, because coverage is a volume rather than a line. On a large area, that shows up directly in detector count, cabling and commissioning.

FirePic and Flame Manager

Set up and maintenance run through the Flame Manager PC app and HART, so configuration doesn’t need the housing opened on a detector mounted at height, and settings are recorded.

Flame Manager includes post event analysis with Honeywell’s FirePic tool. FirePic stores 30 seconds of pre alarm infrared signals for the 10 most recent alarm events, so after an incident you can see what the detector saw, rather than guessing.

Two Versions

The core WideBand detection approach carries across. The Plus modernises configuration, diagnostics, status indication and testing, and adds SIL 2 certification.

At a Glance Status and Simple Testing

A high visibility LED HALO ring shows detector status at a distance: green for normal, yellow for fault or warning, and red for alarm. On a large site, that’s the difference between reading detector status from the ground and needing access equipment.

A simple test lamp allows quick functional testing at a distance, without climbing to the detector. Internal diagnostics, including window clarity, drive maintenance, and the internal electro optics module can be swapped quickly in the field if needed.

Outputs and Integration

Three relays cover alarm, fault and auxiliary, each SPDT, configurable as energised or de-energised and latching or non latching, rated 2 A at 32 VDC. The 4-20 mA output can be set as source, sink or isolated. Digital communications include HART, RS-485 with Modbus and FP2, and USB.

That range of outputs means the detector drops into an existing fire and gas system rather than needing one built around it.

Installation

The FS24X Plus comes with Honeywell’s SM4 graduated mount and a sunshade as standard, which makes mechanical installation straightforward. A marine version mount (SM4-M) is also available. Two cable entries (M25 or 3/4 inch NPT) and plug in connections simplify the electrical work.

The enclosure is low copper aluminium with marine grade paint, or 316 stainless steel, rated IP66 and IP67 (Type 4X). It operates from -55°C to +75°C.

Certification

The FS24X Plus is ATEX and IECEx certified Ex db IIC T5 Gb, with Ex tb IIIC T135°C Db for dust areas. It holds cFMus approval for Class I, Division 1, Groups A, B, C and D, and Class II and III, Division 1, Groups E, F and G, plus INMETRO.

Performance is approved to FM 3260 and EN 54-10 (Class 1 at medium, high and very high sensitivity, Class 2 at low). It’s IEC 61508 SIL 2 certified by TÜV SÜD. Marine type approvals to ABS, Lloyd’s, BV and DNV are pending.

IECEx is the relevant scheme for Australian hazardous areas.

Where It’s Used

Refineries and petrochemical plant. Oil and gas processing and terminals. LNG facilities. Hydrogen production and handling. Offshore platforms and vessels. Turbine halls and enclosures. Aircraft hangars. Waste handling and recycling facilities, where fires are typically dirty. Warehousing and storage. Paint and coating facilities. Mine site fuel storage and processing.