System Sensor HWL-LF Low Frequency Horn

The System Sensor HWL-LF Low Frequency Horn is a wall-mounted audible notification appliance designed to meet the NFPA 72 low-frequency sleeping area requirements for commercial fire alarm systems. As part of the System Sensor L-Series, the HWL-LF produces a 520 Hz square-wave alarm signal specifically engineered to improve occupant awakening during fire emergencies. Therefore, it is an ideal notification solution for hotels, dormitories, apartments, hospitals, assisted living facilities, and other occupancies where low-frequency notification is required.

System Sensor HWL-LF Function

The System Sensor HWL-LF is designed to provide highly effective audible notification during fire alarm events. As a result, occupants receive a low-frequency alarm signal proven to improve awakening performance compared to conventional high-frequency horns. In addition, the sounder integrates easily with compatible 24-volt fire alarm notification appliance circuits (NACs).

520 Hz Low Frequency Alarm

The HWL-LF generates a 520 Hz ±10% square-wave tone, satisfying the low-frequency notification requirements established by NFPA 72 for sleeping areas. Consequently, it provides superior awakening effectiveness for occupants, including individuals with hearing loss or those sleeping under the influence of medication or alcohol. Moreover, the appliance is listed to UL 464 for fire protective service.

Field-Selectable Tone and Volume

The System Sensor HWL-LF features field-selectable operating modes, including Temporal 3, Temporal 4, Continuous, and Coded signaling, along with High and Low volume settings. Therefore, installers can configure the notification appliance to meet the specific requirements of the protected occupancy. Furthermore, all settings are easily selectable without replacing the device.

Easy Plug-In Installation

The HWL-LF utilizes the proven L-Series universal mounting plate with a plug-in design that minimizes intrusion into the electrical box. As a result, installation is faster and more reliable while reducing wiring errors. Additionally, an integrated shorting spring allows installers to verify wiring continuity before attaching the sounder.

Modern Low-Profile Design

The System Sensor HWL-LF features the modern L-Series profile with a durable white housing that complements commercial interiors. Consequently, the appliance provides dependable life safety notification while maintaining an attractive architectural appearance. Its compact design also simplifies replacement of older notification appliances during retrofit projects.

Technical Specifications

• Model: HWL-LF
• Type: Low Frequency Horn
• Manufacturer: System Sensor
• Product Series: L-Series
• Housing Color: White
• Mounting: Wall
• Notification Type: Audible
• Operating Voltage: 24 VDC / FWR
• Operating Voltage Range:
  • 24 VDC: 16–33 VDC
  • MDL3 Sync Module: 16.5–33 VDC
• Alarm Frequency: 520 Hz ±10% Square Wave
• Tone Patterns:
  • Temporal 3
  • Temporal 4
  • Continuous
  • Coded
• Volume Settings: High / Low
• Wiring: Two-Wire NAC
• Wire Size: 12–18 AWG
• Operating Temperature: 32°F to 120°F (0°C to 49°C)
• Humidity: 10–93% RH Non-Condensing
• Dimensions: 5.6″ H × 4.7″ W × 1.5″ D
• Listings:
  • UL 464
  • NFPA 72 Sleeping Area Compliant
• Application: Commercial Fire Alarm Systems for Sleeping Occupancies

Applications

The System Sensor HWL-LF Low Frequency Horn is ideal for:

• Hotels and motels
• Apartment buildings
• Dormitories
• Student housing
• Assisted living facilities
• Hospitals
• Healthcare facilities
• Residential occupancies
• Commercial fire alarm systems
• Sleeping area notification applications

Reliable Low Frequency Audible Notification Solution

The System Sensor HWL-LF Low Frequency Horn combines a 520 Hz NFPA 72-compliant alarm tone, field-selectable operating modes, plug-in installation, and modern L-Series design in a dependable audible notification appliance. Overall, it enhances life safety by providing effective low-frequency alarm signaling for sleeping occupancies while simplifying installation and supporting reliable fire alarm system performance.

HWL-LF