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The Siemens FDO421 Intelligent Smoke Detector P/N: S54320-F4-A1 is an addressable photoelectric smoke detector designed for compatible Siemens fire alarm systems. It uses a dust-resistant optical sensing chamber with microprocessor-based signal processing to provide stable and accurate smoke detection.
The FDO421 is a plug-in, two-wire detector that occupies one address on the signaling line circuit. It also incorporates Siemens ISOtechnology for optional Class X circuit isolation on supported systems.
The FDO421 uses a light-scattering photoelectric sensing principle.
An infrared LED and photodiode monitor the detector’s smoke chamber. When smoke enters the chamber, particles scatter light toward the photodiode. The detector’s microprocessor analyzes the resulting signal to determine the appropriate response.
The dust-resistant chamber and advanced processing algorithms help maintain stable detection while reducing the effects of non-smoke airborne contaminants.
Each FDO421 operates as an individually identifiable device on the compatible Siemens signaling line circuit.
The detector occupies:
One SLC Address
and supports electronic addresses from:
001–252
Individual point identification allows the fire alarm control panel to identify the exact detector reporting an alarm, trouble, or maintenance condition.
The FDO421 does not rely on conventional rotary or DIP switches for addressing.
Detector addresses are programmed electronically using the Siemens:
DPU — Device Programming Unit
The DPU can also be used to perform detector sensitivity measurements and diagnostic functions.
The FDO421 incorporates Siemens ISOtechnology for enhanced signaling line circuit reliability.
On compatible systems and supported detector versions, the built-in isolator can help isolate short-circuit faults while allowing unaffected portions of the signaling circuit to remain operational.
Siemens specifies isolator operation for product version 17 and later when used with a panel that supports this function.
The FDO421 continuously monitors:
Complete diagnostics are performed automatically, helping the fire alarm system identify abnormal detector conditions and maintenance requirements.
The detector provides automatic environmental compensation to help maintain stable sensitivity as environmental conditions or contamination gradually change.
This helps preserve reliable smoke detection performance while reducing unnecessary service calls and unwanted alarms.
The FDO421 incorporates a 360-degree visible status LED capable of displaying:
Green
Yellow
Red
LED operation provides local indication of detector communication, alarm, trouble, and diagnostic conditions according to the connected Siemens fire alarm system.
Compatible Siemens bases include:
DB-11 — Standard Detector Base
DB-11E — Standard Detector Base
The plug-in design allows the detector head to be removed for service or replacement without disturbing the field wiring connected to the base.
The FDO421 supports multiple smoke-detection applications.
Open-Area Detection: Supported
Direct-in-Duct Detection: Supported
Duct Housing Applications: Supported with compatible Siemens equipment
Published air velocity capability extends from:
0–4,000 ft/min
or approximately:
0–20 m/s
For direct-in-duct applications, the appropriate detector parameter must be selected through the compatible Siemens system.
Model: FDO421
Part Number: S54320-F4-A1
Device Type: Intelligent Smoke Detector
Sensing Technology: Photoelectric / Optical
Operating Voltage: 16–30 VDC
Maximum Standby Current: 250 µA
Maximum Alarm Current: 410 µA
Address Range: 001–252
Air Velocity: 0–4,000 ft/min
Operating Temperature: 32°F to 100°F / 0°C to 38°C
Relative Humidity: 0–95%, non-condensing
Status Indicator: Tri-color LED
SLC Addresses Used: One
| Weight | 2 lbs |
|---|---|
| Dimensions | 5 × 5 × 5 in |
| Brand |
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The Siemens FDO421 Intelligent Smoke Detector P/N: S54320-F4-A1 is an addressable photoelectric smoke detector designed for compatible Siemens fire alarm systems. It uses a dust-resistant optical sensing chamber with microprocessor-based signal processing to provide stable and accurate smoke detection.
The FDO421 is a plug-in, two-wire detector that occupies one address on the signaling line circuit. It also incorporates Siemens ISOtechnology for optional Class X circuit isolation on supported systems.
The FDO421 uses a light-scattering photoelectric sensing principle.
An infrared LED and photodiode monitor the detector’s smoke chamber. When smoke enters the chamber, particles scatter light toward the photodiode. The detector’s microprocessor analyzes the resulting signal to determine the appropriate response.
The dust-resistant chamber and advanced processing algorithms help maintain stable detection while reducing the effects of non-smoke airborne contaminants.
Each FDO421 operates as an individually identifiable device on the compatible Siemens signaling line circuit.
The detector occupies:
One SLC Address
and supports electronic addresses from:
001–252
Individual point identification allows the fire alarm control panel to identify the exact detector reporting an alarm, trouble, or maintenance condition.
The FDO421 does not rely on conventional rotary or DIP switches for addressing.
Detector addresses are programmed electronically using the Siemens:
DPU — Device Programming Unit
The DPU can also be used to perform detector sensitivity measurements and diagnostic functions.
The FDO421 incorporates Siemens ISOtechnology for enhanced signaling line circuit reliability.
On compatible systems and supported detector versions, the built-in isolator can help isolate short-circuit faults while allowing unaffected portions of the signaling circuit to remain operational.
Siemens specifies isolator operation for product version 17 and later when used with a panel that supports this function.
The FDO421 continuously monitors:
Complete diagnostics are performed automatically, helping the fire alarm system identify abnormal detector conditions and maintenance requirements.
The detector provides automatic environmental compensation to help maintain stable sensitivity as environmental conditions or contamination gradually change.
This helps preserve reliable smoke detection performance while reducing unnecessary service calls and unwanted alarms.
The FDO421 incorporates a 360-degree visible status LED capable of displaying:
Green
Yellow
Red
LED operation provides local indication of detector communication, alarm, trouble, and diagnostic conditions according to the connected Siemens fire alarm system.
Compatible Siemens bases include:
DB-11 — Standard Detector Base
DB-11E — Standard Detector Base
The plug-in design allows the detector head to be removed for service or replacement without disturbing the field wiring connected to the base.
The FDO421 supports multiple smoke-detection applications.
Open-Area Detection: Supported
Direct-in-Duct Detection: Supported
Duct Housing Applications: Supported with compatible Siemens equipment
Published air velocity capability extends from:
0–4,000 ft/min
or approximately:
0–20 m/s
For direct-in-duct applications, the appropriate detector parameter must be selected through the compatible Siemens system.
Model: FDO421
Part Number: S54320-F4-A1
Device Type: Intelligent Smoke Detector
Sensing Technology: Photoelectric / Optical
Operating Voltage: 16–30 VDC
Maximum Standby Current: 250 µA
Maximum Alarm Current: 410 µA
Address Range: 001–252
Air Velocity: 0–4,000 ft/min
Operating Temperature: 32°F to 100°F / 0°C to 38°C
Relative Humidity: 0–95%, non-condensing
Status Indicator: Tri-color LED
SLC Addresses Used: One
| Weight | 2 lbs |
|---|---|
| Dimensions | 5 × 5 × 5 in |
| Brand |
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