BRK 9120B Smoke Alarm, Dual Ionization, 120V Hardwired w/ Battery Backup

by BRK
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The BRK 9120B smoke alarm is a great choice when it comes to affordability. Redeigned from the ground up, BRK created the 9120B model to directly replace past BRK smoke alarms while greatly improving sensing technology, installation ability, and improved connectivety. The first alert 9120B smoke alarm has an 85dB horn, 9V battery back-up and a silence feature.

The BRK 9120B smoke alarm uses dual ionization technology to reduce false alarms more efficiently and more accurately than ever before. The 9120B smoke alarm is designed for sleeping rooms in your home, hospitals, hotels, motels, college dormatories and multi-family housing units. This BRK smoke alarm complies with NFPA101, UL217, CSFM, NFPA72, HUD, FHA, and other agencies. Where AC/DC silent smoke alarms are required, BRK smoke alarms work perfectly.

The BRK 9120B model has the ability to be interconnected within a circuit of alarms and other alert devices such as bells, whistles, repeaters, fans, or switches. You can connect up to 17 BRK devices of which 11 can be smoke alarms, and 6 can be alternate devices! Integrated within the BRK 9120B smoke alarm is a 9V battery backup to make sure your smoke alarm does not loose operation when power fails which providing added security and peace of mind.

All around, BRK smoke alarms are the perfect choice if you are looking for affordability, function, and ease of use.

BRK Smoke Alarm Replacement

This BRK Electronics 9120B smoke alarm is the direct replacement for the discontinued BRK smoke alarm models 4120B, 4120SB, 4919 and 86RAC. Wiring harness and communication protocol is the same across BRK models (i.e. a 4120B will talk to a 9120B). When replacing an older smoke detector, only the mounting bracket needs to be changed.

About BRK Smoke Alarms

For over 50 BRK smoke alarms have been the preferred smoke alarm to protect lives. BRK makes hardwired, battery operated, and plug-in smoke alarms for professionals, remodeling, homeowners. Designed for easy installation, easy mainatenance. Many BRK smoke alarm models can be interconnected with their patented OneLink® and has quickly become the preference for contractors. Many of BRK smoke alarms 


  • 120 VAC; Interconnectable
  • 9V Battery Included
  • AC Power Indicator
  • Alarm Indication
  • Battery Activation Tab
  • Battery Back-Up
  • Battery Drawer Lock
  • Easy Install Mounting Bracket
  • Ionization Sensor
  • Low Battery Warning "Chirp"
  • Missing Battery Tab
  • Mounting Bracket Lock
  • Quick Plug-In Power Connector
  • Swing-Open Battery Door


  • 120V AC
  • Alarm Dimensions: 5.6" dia x 2.0" H
  • Audio Alarm: 85dB at 10 feet
  • Humidity Range: 10 percent to 90 percent relative humidity (RH)
  • Operating Current: .04 amps (standby/alarm)
  • Operating Voltage: 120V AC 60Hz w/ 9V battery backup
  • Temperature Range: 40 Degree F (4 Degree C) to 100 Degree F (38 Degree C)
  • Weight: 7.8 oz (9120B)


10-year warranty through BRK Electronics

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