The Silent Knight SD505-PHOTO Addressable Photoelectric Smoke Detector is an intelligent smoke detector designed for compatible Silent Knight IntelliKnight fire alarm control panels. It uses photoelectric sensing technology to detect the larger visible smoke particles commonly produced by slow, smoldering fires.

Each SD505-PHOTO has a unique address recognized by the IntelliKnight control panel, allowing the system to identify the exact detector reporting an alarm. It also provides automatic contamination compensation, remote calibration testing, and a built-in functional fire test.

Product Functions

• Provides addressable smoke detection
• Uses photoelectric sensing technology
• Designed for smoldering-fire detection
• Provides individual detector identification
• Automatically compensates for contamination
• Provides built-in functional testing
• Supports detector calibration from the control panel
• Supports remote calibration testing
• Provides LED status indication
• Provides vandal-resistant locking capability
• Field-cleanable detector design
• Uses a removable twist-lock detector base
• Compatible with IntelliKnight fire alarm systems

Photoelectric Smoke Detection

The SD505-PHOTO uses a photoelectric sensing chamber consisting of an LED light source and silicon photodiode receiving element.

During normal operation, the receiving element does not directly receive light from the pulsing LED. When smoke enters the sensing chamber, smoke particles scatter light toward the receiving element.

The detector converts this reflected light into an electronic signal that is evaluated for an alarm condition.

Addressable Operation

Each SD505-PHOTO has a unique address that is recognized by the compatible IntelliKnight fire alarm control panel.

This allows the control panel to identify the exact detector location reporting an alarm rather than only indicating a general conventional detection zone.

The SD505-PHOTO does not use conventional mechanical address switches.

Automatic Contamination Compensation

The detector provides automatic compensation for environmental contamination.

As dust and other contaminants gradually accumulate in the sensing chamber, the detector automatically adjusts to help maintain stable smoke detection performance.

This helps reduce unwanted alarms while maintaining the detector’s intended sensitivity.

Detector Calibration

The SD505-PHOTO allows detector calibration to be selected and measured through the compatible fire alarm control panel.

Calibration testing can also be performed remotely using supported Silent Knight programming software.

This reduces the need for separate external calibration equipment during routine detector servicing.

Built-In Functional Test

The SD505-PHOTO incorporates an automatic functional fire test.

The test electronically simulates the effects of combustion products within the sensing chamber to verify operation of the detector’s internal sensing circuitry.

LED Status Indication

The detector incorporates an integral status LED.

Normal: LED flashes approximately every 15 seconds

Alarm: LED illuminates continuously

The alarm indication remains latched until the detector is reset through the compatible fire alarm control panel.

Compatible Detector Bases

The SD505-PHOTO uses compatible Silent Knight twist-lock detector bases, including:

SD505-6AB — Standard 6-inch Detector Base

SD505-6IB — Isolator Base

SD505-6RB — Relay Base

SD505-6SB — Sounder Base

The standard SD505-6AB base also permits direct interchange with the compatible SD505-HEAT detector.

Electrical & Detection Information

Model: SD505-PHOTO

Device Type: Addressable Photoelectric Smoke Detector

Detection Method: Photoelectric

Operating Voltage: 24–41 VDC

Standby Current: 0.55 mA

Alarm Current: 0.55 mA

Open-Area Air Velocity: 0–300 ft/min

Duct Air Velocity: Up to 4,000 ft/min

Operating Temperature: 32°F to 120°F / 0°C to 49°C

Relative Humidity: Up to 85%, non-condensing

Detector Diameter: Approximately 3-15/16 in.

Height with Base: Approximately 2 in.

Base: Sold separately

SD505-PHOTO Datasheet