Siemens FDOOT441 — an addressable multi-criteria fire detector combining optical and thermal sensing in one head.
The criteria are optical and thermal, not gas. The chamber holds two optical transmitters, one receiver and two thermal sensors: one transmitter lights the smoke from the front and the other from behind, so forward and backward scatter together separate light particles from dark.
- UL 268 7th Edition, UL 268A for direct in-duct use, UL 521 as a heat detector
- UL listed sensitivity 0.88 to 3.35 %/ft; NFPA 76 VEWFD profile at 0.2 and 1.0 %/ft
- 13 to 32 VDC; 650 µA maximum alarm, 360 µA maximum standby
- Five fixed heat thresholds from 135 to 175 °F, four combinable with rate of rise
- Air velocity 0 to 4,000 ft/min open area and in duct; 32 to 120 °F
- 22 application profiles; dual isolators for Class X operation
- Addresses 001 to 252, set with the DPU programmer
The head ships with a dust cover but no base: it needs a DB-11 or DB-11E surface base on a 4 in. octagonal, square or single gang box, or DB2-HR with relay. FDOOTC441 is the near-identical part that adds a carbon monoxide sensor.
