Siemens FDBZ492-HR (S54319-B23-A1) — two-wire addressable air-duct detector housing with a programmable relay base, designed for direct use on HVAC air-duct systems and compatible with the FDBZ492-RTL remote test switch.
The FDBZ492-HR is the housing and relay base: the detector head and the sampling tube are purchased separately. Duct air is drawn through a sampling tube into the housing's sampling chamber, and when equipped the housing signals the presence of smoke being carried through the duct system. The cover is clear with a smoke test port, so the detector type can be identified without opening it, and the head plugs in and out for cleaning or replacement by a trained technician. Installation calls for three small holes for the sampling tube (a template is supplied) and two holes to mount the housing; no mechanical tools are needed to remove the cover or connect the sampling and exhaust tubes. The housing accepts a range of Siemens addressable heads including OOH941, OOHC941, OP921, FP-11, HFP-11, HFPO-11, SFP-11 and SFPO-11, and Models 8710 and 8713.
Specifications
| Part number |
S54319-B23-A1 |
| Type |
Two-wire addressable air-duct detector housing with relays (programmable relay base) |
| Air-duct velocity |
100 to 4,000 ft./min (0.51 to 20 m/sec) |
| Operating temperature |
+32°F (0°C) to 120°F (49°C) |
| Relative humidity |
0 to 95%, non-condensing |
| Sampling tube pressure differential |
Greater than 0.01 in. and less than 1.2 in. of water column |
| Air pressure |
No effect |
| Altitude range |
No limitations |
| Dimensions, rectangular (H x W x D) |
14.38 in. x 5 in. x 2.5 in. (37 cm x 12.7 cm x 6.36 cm) |
| Dimensions, square (H x W x D) |
7.75 in. x 9 in. x 2.5 in. (19.7 cm x 22.9 cm x 6.36 cm) |
| Detector weight |
1.8 lbs. (0.82 kg) |
| Exhaust tube |
Short-return (outlet) tube, approx. 5.5 in. (14 cm) fixed length, supplied with the housing |
| Wiring entries |
Three wiring entry ports |
| Compatible heads |
OOH941, OOHC941, OP921, FP-11, HFP-11, HFPO-11, SFP-11, SFPO-11, 8710, 8713 |
Installation notes
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Three separate purchases: the minimum hardware for a working duct detector is one air-duct housing assembly, one sampling tube, and one detector head. Only the housing assembly is this part number.
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Size the sampling tube to the duct: ST-10 for duct widths 6 in. to 1 ft., ST-25 for 1 ft. to 3 ft., ST-50 for 3 ft. to 5 ft., ST-100 for 5 ft. to 10 ft. The ST-50 and ST-100 both require support, and the ST-100 ships as two 5-ft. pieces with a coupling for field assembly.
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Velocity window is a design constraint: the housing is designed for 100 to 4,000 fpm. Below 100 fpm there is not enough differential pressure across the tube to sample reliably.
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Remote testing: the FDBZ492-RTL key-switch (S54319-S27-A1) mounts remotely, indicates the detector's current state and allows manual relay-output control — the usual answer when the housing sits above a hard ceiling or inside plant.
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Wet or outdoor locations: the FDBZ-WT (S54319-B26-A1) NEMA 4X enclosure is the listed way to install this housing outdoors or where excessive moisture is present.
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Maintenance: the sampling chamber cover comes off for service and the head unplugs, so the housing and tubing can stay in the duct.
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Relay contact ratings are published in a graphical table in the data sheet that does not survive text extraction; confirm them against the printed data sheet or installation instructions before designing interlocks.
Related models
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FDBZ492 (S54319-B22-A1) — the same housing without relays, addressable or conventional
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FDBZ492-R (S54319-B24-A1) — two-wire conventional duct detector housing with relays
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FDBZ492-PR (S54319-B25-A1) — four-wire conventional housing with relays and a built-in power supply, for a self-contained duct detector
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FDBZ492-RTL (S54319-S27-A1) — remote key-switch test station for the -HR, -R and -PR housings
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FDBZ-WT (S54319-B26-A1) — watertight NEMA 4X over-enclosure for any FDBZ492-series housing
Specifications taken from the Siemens data sheet "Cerberus® PRO Specialized Devices, Models FDBZ492, FDBZ492-HR, FDBZ492-R and FDBZ492-PR (with FDBZ-WT and FDBZ492-RTL)," document 9906 (March 2023, Rev. 6). Manufacturer specifications are subject to change without notice.
