Multi Criteria Detectors

Digital Communication of Analog Sensing.
Analog information from each sensor is digitally communicated to the control panel where it is analyzed. Photoelectric sensor input is stored and tracked as an average value with an alarm or abnormal condition being determined by comparing the sensor’s present value against its average value. Thermal data is processed to look for absolute or rate-of-rise temperature as desired.

Intelligent Data Evaluation.
Monitoring each photoelectric sensor’s average value provides a software filtering process that compensates for environmental factors (dust, dirt, etc.) and component aging, providing an accurate reference for evaluating new activity. The result is a significant reduction in the probability of false or nuisance alarms caused by shifts in sensitivity, either up or down. Status indications of dirty and excessively dirty are automatically generated allowing maintenance to be performed per device.

Control Panel Selection.
Peak activity per sensor is stored to assist in evaluating specific locations. The alarm set point for each TrueAlarm sensor is determined at the control panel, selectable as more or less sensitive as the individual application requires.

Multi-Point Reporting and CO Base Reference.
Reporting 4098-9754 “sub-points” under its single address varies with the base used. Muti-point details are listed in data sheet S4090-0011.

Using the 4098-9754 with CO sensor bases is detailed in data sheet S4098-0052.

Timed/Multi-Stage Selection.
Alarm set points can be programmed for timed automatic sensitivity selection (such as more sensitive at night, less sensitive during day). Control panel programming can also provide multi-stage operation per sensor. For example, a 0.2% level may cause a warning to prompt investigation while a 2.5% level may initiate an alarm.

Sensor Alarm and Trouble LED Indication.
Each sensor base’s LED pulses to indicate communications with the panel. If the control panel determines that a sensor is in alarm, or that it is dirty or has some other type of trouble, the details are annunciated at the control panel and that sensor base’s LED will be turned on steadily. During a system alarm, the control panel will control the LEDs such that an LED indicating a trouble will return to pulsing to help identify the alarmed sensors.

General mechanical:

• Housing is sealed against rear air flow entry
• Electronics are EMI/RFI shielded

Smoke sensing:

• Photoelectric light scattering sensing technology
• 360° smoke entry for optimum response
• Chamber screen provides protection from dirt, dust, and insects

Heat sensing:

• Fast response thermistor design
• Rate compensated, self-resetting operation
• Control panel can select per sensor for fixed temperature sensing, rate-of-rise temperature sensing, or the combination of both

TrueAlarm photoelectric sensors use a stable, pulsed infrared LED light source and a silicon photodiode receiver to provide consistent and accurate low power smoke sensing. Seven levels of sensitivity are available for each individual sensor, ranging from 0.2% to 3.7% per foot of smoke obscuration. Sensitivities of 0.2%, 0.5%, and 1% are for special applications in clean areas. Standard sensitivities are 1.5%, 2.0%, 2.5%, 3.0%, and 3.7%. Application type and sensitivity are selected and then monitored at the fire alarm control panel.*

Sensor head design provides 360° smoke entry for optimum smoke response. Because of the photoelectric sensing technology, the 4098-9754 sensor is UL listed for air velocity of up to 4000 ft/min. However, care must be taken in determining sensor locations to avoid areas where local airflow may also impact any smoke flow.

TrueAlarm heat sensors monitor a fast reacting thermistor providing operation that is self-restoring and rate compensated. Due to its small thermal mass, the sensor accurately and quickly measures the local temperature for analysis at the fire alarm control panel. The control panel allows alarm selection to be per sensor as fixed temperature, or rate-of-rise temperature, or the combination of both.

Temperature Detection. Rate-of-rise temperature detection is selectable at the control panel for either 15° F (8.3° C) or 20° F (11.1° C) per minute. Fixed temperature sensing is independent of rate-of-rise sensing and selectable to operate at 135° F (57.2° C) or 155° F (68° C). In a slow developing fire, the temperature may not increase rapidly enough to operate the rate-of-rise feature. However, an alarm will be initiated when the temperature reaches its selected fixed temperature setting.

Utility Temperature Monitoring. TrueAlarm heat sensors can be programmed as a utility device to monitor for temperature extremes in the range from 32° F to 122° F (0° C to 50° C). This feature can provide freeze warnings or alert to HVAC system problems.

Control Panel Sensor Analysis. Each multi-sensor’s smoke and heat sensing element provides data for evaluation at the fire alarm control panel where four independent detection modes are evaluated. They are:

• Fixed temperature heat detection
• Rate-of-rise heat detection
• TrueAlarm photoelectric smoke detection
• And TrueSense correlation detection

Comparing Photoelectric Activity and Thermal Activity.
TrueSense analysis correlates both thermal activity and smoke activity at a single multi-sensor location using an extensively tested covariance relationship. As a result, TrueSense detection improves response to conditions indicative of faster acting, hot flaming fires when compared to the response of either photoelectric smoke activity or thermal activity alone.

High Integrity Detection.
TrueSense operation provides early fire detection and maintains the established high level of immunity to false alarms and nuisance alarms that is inherent with TrueAlarm sensor operation.

Sensor locations should be determined after careful consideration of the physical layout and contents of the area to be protected. Refer to NFPA 72, the National Fire Alarm and Signaling Code. On smooth ceilings, smoke sensor spacing of 30 ft (9.1 m) may be used as a guide.*

Base mounted address selection allows the address of the multi-sensor base to remain with its programmed location when the sensor is removed for service.

Integral red LED indicates power-on by pulsing, or alarm or trouble when steady on, reflecting status of either sensor. The exact status of the specific sensing element is annunciated at the fire alarm control panel.

• Individual smoke sensitivity and temperature operation is selectable for each sensor
• Sensitivity monitoring that satisfies NFPA 72 sensitivity testing requirements
• Peak value logging allows accurate analysis for sensitivity selection
• Automatic, once per minute individual sensor calibration check verifies sensor integrity
• Multi-stage alarm operation
• Selectable alarm verification
• Automatic environmental compensation and determination of dirty and excessively dirty
• TrueSense analysis of smoke and heat activity
• Ability to display and print detailed sensor information in plain English language
• Smoke sensitivity displayed in percent per foot and temperature readings selectable as Fahrenheit or Celsius