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      • Published 18 Dec 2023
      • Last Modified 29 Jan 2024
    • 5 min

    What is a Sounder in an Alarm System?

    Electronic sounders and electronic sensors are used in industrial environments to raise the alarm if there is a fire or other emergency. Sensors come in a variety of forms and may detect changes in temperature or the emission of smoke. The electronic sounders used in industry can be specifically designed to cut through noisy working environments, or ruggedised to deal with harsh conditions. Read on to find out what electronic sounders, alarm sounders, and sensors do, and where they are used.

    electronic sounders

    Reviewed by Stephen Bettles, Technical Support Engineer (November 2023)

    Electronic sounders and sensors are a vital part of all commercial and industrial alarm systems. They are used in a wide range of environments, including commercial buildings and manufacturing facilities. The alarm sounder is the component that produces a noise when the alarm is triggered. 

    Some electronic sounders are specifically designed for demanding industrial settings, featuring high levels of durability and impact resistance. They are also highly visible for the workplace and loud enough to cut across the noise of machinery. For example, we have electronic sounders that deliver output of up to 116 decibels. 

    Read on to find out more about sensors, electronic sounders, alarm sounders, and commercial alarm systems, and how they work. 

    How Do Industrial Fire Alarm Systems Work?

    Industrial fire alarm systems use sensors to detect changes in temperature, the presence of smoke or a combination of both. Thermistors are used to detect heat from a fire, while smoke can be detected using ionisation or photoelectric sensors.

    A thermistor, or thermal resistor, is a semiconductor whose resistance varies based on temperature. Negative temperature coefficient (NTC) thermistors are commonly used in fire alarm systems as temperature sensors. Their resistance decreases with increased temperature and can be used to trigger an alarm.

    Smoke detectors may use a radioactive isotope to ionise a small volume of air, allowing a current to be conducted across an air gap. The presence of smoke in the unit will absorb the alpha radiation, eliminating the movement of ions and triggering the alarm.

    An alternative smoke detector uses a light source which is reflected onto a photoelectric sensor by the presence of smoke. These photoelectric smoke alarms are more useful for slow-burning, smouldering fires, while ionisation smoke alarms respond quickly to fast-burning, flaming fires.

    When the fire sensor is triggered, the most important output is an audible alarm sounder so that the building can be evacuated as soon as possible. Other outputs may include visual outputs on a control panel to identify the location of the problem, along with automatic contacting of the emergency services. 

    How to Build an Alarm Circuit

    An industrial alarm circuit consists of sensors, a control panel and a trigger. The function of the sensors is to detect a stimulus. That may be motion in commercial intruder alarm systems, or heat or smoke in a fire alarm system for commercial buildings. 

    The trigger acts in response to the sensor. The most common output is a noise produced by an electronic sounder or alarm sounder, but outputs can also include lights or automated messages and phone calls. Sprinklers can also be triggered by a fire alarm in larger installations. 

    The control panel is used to turn the alarm on and off, usually via a security code entered on a keypad. Depending on the complexity of the system, the control panel may also display different areas and allow adjustment of different settings.

    Commercial intruder alarms and fire alarm systems for commercial buildings are usually mains-powered, although a backup battery power source is common to ensure continuity during power cuts.

    Alarm systems may have wired connections or operate wirelessly depending on the needs of the setting and the type of installation required.

    Alarm Systems Equipment

    Commercial alarm systems equipment varies depending on the type of installation and the size of the building. Every system will need some or all of the following equipment:

    alarm sounder

    Industrial Electronic Sounder / Alarm Sounder

    The alarm sounder is an essential part of a commercial system, alerting employees to the emergency. Sounders are usually wall-mounted and installed at key locations around the facility to ensure complete coverage. A range of electronic sounders is available, with a variety of sounds including sirens, klaxons, buzzers, horns and even voice recordings used to convey evacuation instructions.

    Electronic sounders can also be ruggedised for industrial applications and loud enough to be heard in very noisy environments where production machinery is being used. Different sounds can also be used to indicate different types of incidents are taking place. 

    Some electronic sounders are combined with lights to produce audio and visual alerts. To choose the correct sounder for your alarm installation, consider the needs of the specific building. Think through the required volume and number of positions which need a sounder. 

    With a range of IP ratings, ATEX-approved options and durable construction, RS has a comprehensive range of electronic sounders. 

    Browse Alarm Sounders & Strobes

    Alarm Sensors

    A range of alarm sensors is used depending on the purpose of the alarm.

    For fire alarms:

    • A thermistor-based sensor may detect temperature increases.
    • An ionisation sensor may be used for smoke detection.
    • A photoelectric sensor can be used for smoke detection.

    For intruder alarms:

    • Magnetic sensors detect the opening of doors and windows.
    • Glass-break sensors include a microphone to detect the sound of breaking glass.
    • Passive infrared (PIR) sensors detect motion.
    • Vibration sensors detect forced entry.

    Control Panel

    The complexity of the control panel of a commercial alarm system will depend on the needs of the installation. At the most basic level, the control panel allows the commercial alarm system to be set and reset, usually by entering a numerical code. More advanced control panels allow separate zones of a factory or commercial premises to be controlled separately. They may display information about where the alarm has been triggered.

    How to Change Alarm Noise

    Changing the alarm noise will depend on the type of electronic sounder you are using. Some alarm sounders offer a choice of tone, with the ability to adjust volume. If you need a variety of tones, our range of electronic sounders features 32 to 80 tones.

    At RS, we have a range of components for every part of your commercial alarm system. Explore our complete collection of security alarms and sensors.

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