Installation: Notifier FST-951AUS Intelligent Temperature Sensors Instruction Manual

Overview

The FST-951AUS Intelligent Temperature Sensors are addressable thermal detectors designed for compatible fire alarm control systems. The FST-951AUS and FST-951AUS-IV provide fixed-temperature detection at 57°C, while related models in the same series add rate-of-rise or high-temperature operation.

These sensors are intended for professional fire detection installations where the control panel communicates with each device individually. A separate compatible sensor base is required for mounting and wiring.

Specifications

• Model range: FST-951AUS, FST-951AUS-IV, FST-951RAUS, FST-951RAUS-IV, FST-951HAUS, and FST-951HAUS-IV
• Operating voltage: 15–32 VDC
• Peak operating current: 200 µA at 24 VDC
• Maximum alarm current: 2 mA at 24 VDC
• Maximum current: 4.5 mA at 24 VDC
• Humidity range: 10%–93% relative humidity, non-condensing
• Fixed-temperature rating: 57°C
• High-temperature rating: 88°C
• Rate-of-rise response: More than 8.3°C per minute for rate-of-rise models
• Installation temperature: –10°C to 50°C for fixed-temperature and rate-of-rise models; –10°C to 80°C for high-temperature models
• Installed height: 51 mm with a compatible B501 series base
• Installed base diameter: 156 mm with compatible B501 bases
• Sensor weight: 95 g
• Addressing: Rotary decimal addressing up to 159 device addresses
• Standards: NZS4512 and AS ISO 7240.5:2018
• Classifications: A2S for FST-951AUS models, A2R for FST-951RAUS models, and Class C for FST-951HAUS models

Detailed Description

The FST-951AUS Intelligent Temperature Sensors use a thermistor sensing circuit to monitor temperature changes and provide rapid communication to an addressable fire alarm panel. The standard FST-951AUS models operate as 57°C fixed heat detectors and respond when the monitored temperature reaches the fixed alarm threshold.

FST-951RAUS models combine the 57°C fixed-temperature function with rate-of-rise detection. These models can respond when temperature increases by more than 8.3°C per minute. FST-951HAUS models are designed for high-temperature applications and use an 88°C alarm rating.

Each sensor includes two visible LEDs. Depending on the capabilities and programming of the control panel, the LEDs may be configured to remain on, remain off, or blink. The panel may also select red, green, or amber indication and can control an optional remote annunciator independently or in synchronization with the sensor LEDs.

A rotary address switch assembly contains separate tens and ones controls. This allows the control panel to identify the sensor as an individual point on the communication loop. FST-951AUS, FST-951RAUS, and FST-951HAUS models support FlashScan protocol. The corresponding ivory models support either FlashScan or CLIP protocol when used with a panel that provides those functions.

The sensor plugs into a separately supplied base. Compatible base options include B501BI-IV, B501BI-W, B501AUS-W, and B501AUS-IV. The base simplifies service because the wiring can remain in place while the detector is removed.

Safety

• Install the sensor only on a listed-compatible addressable fire alarm control panel.
• Follow the control panel installation manual, applicable electrical codes, and instructions from the Authority Having Jurisdiction.
• Apply sensor spacing, placement, zoning, and special-application requirements according to AS 1670.1 and the requirements of the relevant authority.
• Disconnect power from the communication line before installing or removing a sensor.
• Use the correct wire gauge and color-code conductors where practical to reduce connection errors and simplify troubleshooting.
• Do not loop wiring under terminals 1 or 2. Break the wire run as required so the connections remain supervised.
• Do not install a product if its packaging seal is broken or there are signs of tampering.
• Protect the complete fire alarm system, including sensors, bases, panels, and wiring, against unauthorized access or interference.

Setup and Operation

Prepare the installation

Before fitting the FST-951AUS Intelligent Temperature Sensors, read the fire alarm system wiring and installation documentation. Confirm that the selected panel, communication protocol, sensor model, and base are compatible with one another.

Plan sensor positions and spacing in accordance with AS 1670.1 and the requirements of the Authority Having Jurisdiction. The correct location depends on the room layout, ceiling construction, environmental conditions, and the intended fire detection strategy.

Install the sensor

1. Remove power from the addressable communication line.
2. Wire the separately supplied sensor base according to the system wiring diagram.
3. Set the required device address using the rotary tens and ones switches.
4. Align the sensor with the base and push it into position while turning it clockwise until it is secure.
5. After all devices have been installed, restore power to the control unit and activate the communication line.
6. Test each sensor using an approved method before placing the system into service.

LED and remote indication

LED behavior is controlled by the fire alarm panel. A green blink may indicate normal communication, while a red steady indication may accompany an alarm condition. Amber indication may be used for other panel-controlled states. Exact behavior depends on the control panel model and its programming.

An optional remote annunciator can extend local indication when permitted by the system design. The panel may synchronize the remote output with the sensor LEDs or control it separately.

Tamper resistance

The sensor includes a tamper-resistant feature that can prevent removal from its base without a tool. Use this function only as described in the instructions for the selected sensor base.

Testing

Notify the proper authorities before testing and place the affected system or zone into the required maintenance condition. Disable the system as necessary to prevent unwanted alarms or emergency responses. Testing must follow the requirements of the Authority Having Jurisdiction and the maintenance practices specified by AS 1670.1.

Magnet test

1. Place the optional test magnet over the marked magnet test area on the detector cover.
2. Confirm that the LEDs latch on within 10 seconds and that the control panel annunciates an alarm.
3. Reset the detector from the fire alarm control panel.

Direct heat test

1. Direct suitable heat toward the side of the detector.
2. Keep the heat source approximately 15 cm from the cover to reduce the risk of damage.
3. Continue the test until the detector reaches its alarm setpoint and the LEDs illuminate.
4. If the LEDs do not operate, inspect power and base wiring before repeating the test.
5. Reset the detector from the control panel.

Do not leave the system disabled after testing. Restore all circuits and notify the responsible authorities that the fire alarm system is back in service.

Cleaning and Maintenance

Test every sensor after installation and at regular intervals thereafter. Sensors that fail an approved test may require cleaning before being tested again.

1. Notify the appropriate authorities and disable the zone or system being serviced.
2. Remove the sensor from its base.
3. Use a vacuum cleaner or compressed air to remove dust and debris from the sensing area and thermistor access area.
4. Reinstall the sensor in its base.
5. Test the detector using an approved testing procedure.
6. Reconnect any circuits that were disabled during maintenance.
7. Notify the appropriate authorities that the system has returned to normal operation.

When replacing or scrapping the sensor, dispose of the electronic device according to applicable national and local regulations. Do not place it in general household waste.

Troubleshooting

Sensor does not communicate

• Confirm that the communication line is powered.
• Check that the sensor is installed on a compatible control panel and that the selected protocol is supported by the model.
• Verify the rotary address settings and make sure the address is not duplicated by another device.
• Inspect the base wiring, terminal connections, wire polarity, and supervision arrangement.
• Ensure that the sensor is fully seated and locked into the base.

Alarm test does not operate

• Confirm that the system or zone has been returned to an enabled testing state.
• Check power and wiring at the detector base.
• Clean dust and debris from the sensing area, then repeat the approved test.
• Verify that the test method is appropriate for the installed sensor type and its alarm rating.
• Reset the detector at the control panel after every alarm test.

Unexpected alarm or indication

• Review the control panel event information and confirm the device address.
• Check whether the detector is installed in an area with temperatures or rapid heat changes unsuitable for its model.
• Inspect the sensor and base for contamination, damage, loose connections, or signs of tampering.
• Have qualified fire alarm personnel assess the installation before returning it to normal service.

Pros and Cons

Pros

• Individual addressability helps identify the exact detector reporting an event.
• Thermistor-based sensing provides responsive heat detection.
• Separate bases simplify sensor replacement and maintenance.
• Rotary addressing supports straightforward device identification.
• Multiple series variants cover fixed-temperature, rate-of-rise, and high-temperature applications.
• Visible LEDs and optional remote indication support local system status awareness.

Cons

• The sensor requires a compatible addressable control panel and separately supplied base.
• Installation, spacing, testing, and maintenance must follow fire protection codes and authority requirements.
• LED behavior and available communication features vary by control panel.
• Incorrect wiring, addressing, or unsuitable placement can prevent proper alarm response.