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SLR-24V - Hochiki Photoelectric Smoke Detector Head

Hochiki: SLR-24V Photoelectric Smoke Detector Head

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The SLR-24V can be used in all areas where Photoelectric Smoke Detectors are required. The wide range smoke chamber makes the SLR-24V well suited for fires ranging from smoldering to flaming fires.  NS-4 Series, NS-6 Series, HSC-4R or HSC-xxx R Style bases may be used with the SLR-24V. Current interchangeable/compatible devices are the SIJ-24 ionization detector, the SLR-24H photoelectric detector with heat sensor, and the DCD-135/190 heat detectors.

All NS conventional devices are mechanically compatible with Hochiki America HSB, HSC and YBA type bases which may have been used in previous installations. Please check individual panel listings for compatible bases.


The SLR-24V photoelectric smoke detector utilizes two bicolored LEDs for indication of status. In a normal standby condition the LEDs flash Green every 3 seconds. When the detector senses that its sensitivity has drifted outside the UL listed sensitivity window the LEDs will flash Red every 3 seconds. When the detector senses smoke and goes into alarm the status LEDs will latch on Red.

The detector utilizes an infrared LED light source and silicon photo diode receiving element in the smoke chamber. In a normal standby condition, the receiving element receives no light from the pulsing LED light source.

In the event of a fire, smoke enters the detector smoke chamber and light is reflected from the smoke particles to the receiving element. The light received is converted into an electronic signal.

Signals are processed and compared to a reference level, and when two consecutive signals exceeding the reference level are received within a specified period of time, the time delay circuit triggers the SCR switch to activate the alarm signal. The status LEDs light continuously during the alarm period.

  • Includes: (1) SLR-24V Bone Photoelectric Smoke Detector Head
  • Low profile, 1.8" high (with base)
  • 2 or 4 wire base compatibility, relay bases available
  • Highly stable operation, RF/Transient protection
  • Low standby current, 45μA at 24VDC
  • Two built-in power/sensitivity supervision/alarm LEDs
  • Non-directional smoke chamber
  • Vandal resistant security locking feature
  • Built-in magnetic go/no go detector test feature
  • Removable smoke labyrinth for cleaning or replacement
  • Automatic Sensitivity window verification function meets outlined requirements in NFPA 72, Chapter 2 & 7, Inspection, Testing and Maintenance
  • Compatible with SIJ-24 ionization detectors
  • Backwards compatible with Hochiki SLK and SIH detectors
  • Light Source: GaAlAs Infrared Emitting Diode
  • Rated Voltage: 17.7 - 30.0 VDC
  • Working Voltage: 15.0 - 33.0 VDC
  • Maximum Voltage: 42 VDC
  • Supervisory Current: 45μA @ 24 VDC
  • Surge Current: 160μA max. @ 24VDC
  • Alarm Current: 150mA max. @ 24 VDC
  • Air Velocity Range: 0-4000 fpm
  • Ambient Temperature: 32°F to 120°F (0°C to 49°C)
  • Color & Case Material: Bone PC/ABS Blend
  • Sensitivity Test Feature: Automatic Sensitivity - Window Verification Test
  • Mounting: Refer to NS Conventional - Detector Base Data Sheet
  • Part#: SLR-24V