Siemens FDOT421 Multi-Criteria Fire and Smoke Detector P/N: S54320-F6-A1

The Siemens FDOT421 Multi-Criteria Fire and Smoke Detector P/N: S54320-F6-A1 is an intelligent addressable detector designed for compatible Siemens fire alarm systems. It combines photoelectric smoke sensing and electronic heat detection to provide multi-criteria fire detection with strong nuisance-alarm rejection. Siemens officially identifies the FDOT421 as an Addressable Multi-Criteria Fire Detector.

The detector’s microprocessor continuously evaluates smoke, temperature, sensitivity, and internal electronics. It can provide combined smoke/heat detection as well as a separate heat alarm source through compatible Siemens control equipment.

Product Functions

• Provides intelligent addressable fire and smoke detection
• Combines photoelectric smoke and thermal sensing
• Provides multi-criteria alarm processing
• Provides 135°F fixed-temperature detection
• Provides rate-of-rise heat detection
• Helps reject nuisance conditions
• Supports built-in line isolation on compatible product versions
• Supports electronic device addressing
• Provides individual point identification
• Provides continuous self-monitoring
• Uses a tri-color status LED
• Supports compatible Siemens detector bases
• Supports open-area and direct-in-duct applications

Multi-Criteria Fire & Smoke Detection

The FDOT421 combines information from its photoelectric smoke sensor and thermal sensor to evaluate developing fire conditions.

This multi-criteria architecture allows the detector to respond to a broad range of combustion products while improving rejection of nuisance sources such as:

• Dust
• Steam
• Aerosols
• Other deceptive airborne phenomena

The combined sensing approach provides more information for alarm decisions than a basic single-sensor smoke detector.

Photoelectric Smoke Detection

The optical sensing chamber monitors airborne smoke particles.

As smoke enters the chamber, changes in the optical signal are evaluated by the detector’s onboard electronics. This smoke information can then be combined with thermal data to determine the appropriate system response.

The detector continuously monitors smoke within its chamber as well as whether its sensitivity remains within the specified range.

Thermal Detection

The FDOT421 provides electronic heat detection in addition to smoke sensing.

Fixed Temperature: 135°F / 57°C

Rate-of-Rise: 15°F per minute / 8.3°C per minute

Compatible Siemens systems can treat the detector’s combined smoke/heat response and heat-only response as separate programmable alarm sources.

Electronic Addressing

The FDOT421 uses electronic addressing rather than mechanical rotary or DIP switches.

Supported address range:

001–252

Detector addresses are programmed using the Siemens DPU Device Programming Unit. The DPU can also be used for individual detector sensitivity testing and diagnostics.

Built-In Isolation

Compatible FDOT421 product versions incorporate line-isolation functionality.

When operating in isolator mode with supported Siemens control equipment, the detector can help isolate a short circuit on the signaling line while allowing unaffected portions of the loop to continue operating.

Siemens specifies that isolator mode applies to FDOT421 product version 17 and later and should not be used on earlier versions.

Tri-Color LED

The FDOT421 incorporates a status LED capable of displaying:

Green

Yellow

Red

The detector’s microprocessor monitors smoke conditions, sensitivity, internal sensors, and electronics, with the LED providing local status information according to detector and system conditions.

Detector Base Compatibility

Compatible Siemens detector bases include:

DB-11 — Standard low-profile base

DB-11E — Smaller-diameter detector base

DB2-HR — Relay detector base

The separate plug-in base design allows the detector head to be serviced or replaced without disturbing the installed field wiring.

Electrical & Detection Information

Model: FDOT421

Part Number: S54320-F6-A1

Device Type: Multi-Criteria Fire and Smoke Detector

Smoke Sensing: Photoelectric

Heat Sensing: Fixed Temperature / Rate-of-Rise

Fixed Temperature: 135°F / 57°C

Rate-of-Rise: 15°F/min / 8.3°C/min

Input Voltage: 16–30 VDC

Maximum Standby Current: 250 µA

Maximum Alarm Current: 410 µA

Address Range: 001–252

Operating Temperature: 32°F to 100°F / 0°C to 38°C

Relative Humidity: 0–95%, non-condensing

Status Indicator: Tri-color LED.

FDOT421 Datasheet