Siemens FDO421 (S54320-F4-A1) — plug-in, two-wire addressable photoelectric smoke detector for the Desigo Fire Safety platform, using a light-scattering optical sensor with microcontroller-based signal processing.
The FDO421 pairs a dust-resistant photoelectric chamber with microprocessor-based electronics in a low-profile plastic housing, and ships with a protective dust cover. Advanced software algorithms analyse the optical signal for highly stable and accurate smoke detection, with automatic environment compensation and strong immunity to electromagnetic and radio-frequency interference. The panel selects one of four pre-programmed application parameter sets — Sensitive, Standard, Robust or Air-duct — so the same head can be tuned to a clean data room or to a space where exhaust fumes would otherwise cause nuisance alarms. The detector is UL Listed as self-testing, runs complete diagnostics every ten seconds, and needs no field sensitivity test. A tri-color LED gives 360-degree status indication and SureWire technology makes wiring polarity insensitive.
Specifications
| Part number |
S54320-F4-A1 |
| Detector type |
Plug-in, two-wire addressable photoelectric (light-scattering optical) smoke detector |
| Operating temperature |
+32°F to +120°F (0°C to +49°C) |
| Relative humidity |
0 to 95%, non-condensing |
| Air pressure |
No effect |
| Air velocity |
0 to 4,000 feet per minute (0 to 20 m/s) |
| Input voltage range |
16 VDC to 30 VDC |
| Alarm current, max. |
280 µA |
| Standby current, max. |
280 µA average |
| Maximum spacing |
30-ft. centers (900 sq. ft.), per NFPA 72 |
| Detector weight |
0.317 lbs. (0.144 kg) |
| Application parameter sets |
Four: Sensitive, Standard (default), Robust, Air-duct |
| Self-diagnostics |
Complete diagnostics every 10 seconds; sensitivity self-monitored within UL Listed limits |
| Compatible panels |
Desigo Fire Safety FC2005 (50-point), FC2025 (252-point), FC2050 (504-point), FV2025 and FV2050 (with IVC), Desigo Modular; FireFinder XLS and XLSV |
| Mounting base |
DB-11 (500-094151) or DB-11E (500-094151E); ordered separately |
| Mechanical protection guard |
UL and ULC Listed with STI Guard Model STI-9604 |
| Listings and approvals |
UL 268A Listed for direct air-duct use, ULC Listed; FM (#3230, #3210) and CSFM (#7272-0067:0258) Approved; RoHS compliant |
Installation notes
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Base ordered separately: the head plugs into a DB-11 or the smaller DB-11E, on a 4-inch octagonal, square or single-gang box. In Canada order the DB-11C (500-095687).
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Choose the parameter set to the room: Standard is the default for office and lobby space; Robust buys nuisance-alarm resistance where cigarette smoke or exhaust fumes are present; Sensitive is for clean, controlled areas where the earliest possible detection matters.
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Direct in-duct without a housing: the Air-duct parameter set is what makes this a UL 268A (DI) compliant direct in-air-duct installation. If a duct housing is used instead, the FDBZ492 series is the housing to specify.
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No field sensitivity test required: the detector self-monitors sensitivity and reports it remotely at the panel.
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Guarding: the STI-9604 is the guard listed with this detector; other cages are not part of a listed assembly.
Related models
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OP921 (S54320-F4-A2) — the identical detector with identical published technical data, catalogued for the Cerberus PRO platform instead of Desigo Fire Safety
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FDOT421 (S54320-F6-A1) — multi-sensor optical and thermal head on the same platform
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FDOOTC441 (S54320-F8-A1) — multi-criteria fire and CO detector, where CO sensing is wanted
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FDT421 (S54320-F5-A1) — thermal-only heat detector for spaces where smoke sensing is unsuitable
Specifications taken from the Siemens data sheet "Desigo® Fire Safety Photoelectric Smoke Detector, Model FDO421," document 6152 (October 2017, Rev. 6). Manufacturer specifications are subject to change without notice.
