The Modularm Model 75 Temperature Monitoring System is designed to constantly monitor temperature and provide audible, visual, and remote notification whenever refrigeration failure occurs. It is available in several versions, including the Model 75B with battery backup and the Model 75C with thermostatic control.
Function Description:
The core function of the Modularm Model 75 is to monitor ambient temperature in environments such as walk-in coolers or freezers using an electronic temperature probe. When the monitored temperature goes above or below user-defined setpoints, an electronic time delay circuit is activated. This time delay is crucial for overriding short-term temperature fluctuations, such as those caused by defrost cycles, to prevent false alarms. If the temperature remains outside the setpoints beyond the selected time delay, the alarm activates, providing audible and visual alerts, and, if connected, remote notification.
The Model 75B (Battery Backup option) extends this functionality by annunciating power failures. When a power failure occurs, the green "Safe" light extinguishes, the red "Alarm" light blinks, the horn beeps intermittently, and the internal relay activates for remote notification.
The Model 75C (Thermostatic Control option) adds temperature control capability. Its control circuitry operates as an "on-off" type thermostat, maintaining temperature between a selected high limit setpoint and a differential (low limit) setting. This allows the device to activate secondary controlling devices (e.g., contactor coils or solenoids) to regulate temperature.
Important Technical Specifications:
- Dimensions:
- Surface Mount: 9"L x 4"W x 1.8"D
- Flush Mount: Flange Dimension – 10.375"L x 4.75"W; Cutout Dimension – 9.375"L x 4.375"W
- Enclosure: Drawn aluminum with stainless steel faceplate.
- Temperature Range: -40°F to 212°F (-40°C to 100°C). Other ranges are available.
- Setpoint Range: -40°F to 120°F (-40°C to 50°C). Other ranges are available.
- Time Delay: Adjustable from 10 to 150 minutes in 10-minute increments. Other ranges are available.
- Audible Notification: Piezo type horn; Frequency -3.8kHz; SPL – 85dB @ 3' typical.
- Visual Notification: Green LED (Safe Light), Red LED Blinking (Abnormal Temperature), Red LED Solid On (Alarm Condition).
- Remote Notification:
- Dry Contacts: Normally Open (N/O) & Normally Closed (N/C); Current Capacity – 6A @ 120/240VAC, 6A @ 28VDC.
- Pulse Output: 6VDC for 1 second (used to trigger available auto dialer).
- Sensor: Electronic, 1.75"L x .375”DIA. with 25' wire. The wire can be lengthened in excess of 1000' or shortened without affecting accuracy.
- Operating Power: 120VAC, 1φ45mA.
- UL Listed: The Model 75 and 75B Temperature Alarms are UL Listed Products (File #E187350). UL Listed versions feature individual 18 gauge wires for remote notification functions, replacing the terminal strip found in non-UL versions.
Usage Features:
The Modularm Model 75 offers a user-friendly interface with several controls and indicators:
- Display Reset, Alarm Test Switch (A): Sliding left stops the digital readout from blinking and provides a constantly on temperature display. Sliding right activates TEST MODE, displaying "---F" or "---C" and activating the alarm within 3-30 seconds (depending on time delay).
- Display Mode Switch (B): Selects between Fahrenheit or Centigrade display.
- Alarm Control Switch (C): Disables or resets the alarm. This switch has two positions, and for all monitored conditions, there is only one position where the alarm will be silent. This design prevents accidental disabling.
- Battery Test Switch (D) (75B only): Checks the condition of the rechargeable backup battery.
- Setpoint Display Switch (E): Holding up displays the High Setpoint; holding down displays the Low Setpoint.
- Time Delay Select Switch (F): A switch matrix with four switches allows selection of time delays from 10 to 150 minutes in 10-minute increments. At least one time delay switch must be selected for proper alarm function.
- Status Lights (G, H): Green light indicates "Safe" condition; Red light indicates "Abnormal or Alarm Condition."
- Setpoint Adjustments (I, J): Allows adjustment of high and low alarm temperature setpoints.
- Dry Contacts, Pulse Output Terminal Strip (K): Provides connections for remote notification equipment such as bells, sirens, lights, dialers, or central stations.
- Calibration Switches (L): Located on the digital readout module, these switches are used for calibrating the digital readout.
Operating Sequence:
- Normal Operation: Green light is on, red light is off.
- Abnormal Condition (Time Delay Initiated): Green light extinguishes, red light blinks.
- Alarm Condition (Time Delay Exceeded): Solid red light, horn sounds, relay activated, and a 6-volt, one-second pulse is generated across pulse output terminals.
- Power Failure (75B only): Green light extinguishes, red light blinks, horn beeps intermittently.
When an alarm condition occurs, the ALARM CONTROL SWITCH is thrown towards the RED LIGHT to silence the horn and release the relay. The RED LIGHT remains on to indicate the alarm condition. Restoration of a safe condition will cause the alarm to sound again, requiring the ALARM CONTROL SWITCH to be returned to the safe position.
Special Options:
- Panic Alarm: Provides a means for personnel inadvertently locked in a compartment to activate the alarm. A twisted pair of wires connects to a toggle or push-button switch (not provided) installed inside the compartment.
- Door Ajar: Annunciates when a compartment door is left open for longer than a specified time (e.g., 10 minutes). A yellow "DOOR AJAR" light glows, and the alarm begins to "time out." If the door remains open beyond the set time, the alarm annunciates. Closing the door resets the alarm unless a temperature alarm is also active.
- 75MP (Multi-Probe): A 2, 3, or 4 probe version of the Model 75 for monitoring large rooms or multiple temperature-sensitive areas. The alarm scans and displays probe temperatures at four-second intervals.
Maintenance Features:
- Calibration: If the Model 75 is not reading temperature properly, it can be calibrated. This involves removing the faceplate, using an accurate reference thermometer in contact with the probe (or an ice bath), and adjusting the CALIBRATION SWITCHES until the displayed temperature matches the reference. After calibration, setpoints should be rechecked and readjusted.
- Battery (75B only): The battery is rechargeable, and the 75B unit contains charging circuitry. The BATTERY TEST SWITCH allows checking its condition.
- Probe Wire: The sensor wire can be lengthened or shortened without affecting accuracy, but proper polarity (white to white, black to black) must be observed when reconnecting. Splices in the monitored compartment should be sealed with silicone to prevent moisture, and openings where the probe extends into the compartment should also be sealed. It is critical not to run the sensor line for extended distances in conduit with high voltage or "bouncing" wires, as this can cause erroneous readings.
- UL Listed Wiring: For UL Listed versions, the remote notification wiring consists of individual 18 gauge wires with a specific color code (Blue for N/O, Purple for Common, Yellow for N/C, Grey for Pulse Output Negative, Red for Pulse Output Positive). Black and white wires are for 120VAC, and the green wire is ground. Retrofitted devices must be used with a suitable wiring compartment according to NEC code.
Installation:
- Remove the faceplate by unscrewing the two retaining screws.
- Mount the unit in a suitable location:
- Surface Mount: Use the four mounting holes on the back wall of the enclosure.
- Flush Mount: Cut out a 9 3/8" high x 4 3/8" wide opening in the mounting surface and use the four mounting holes on the front flange.
- Run the temperature probe into the monitored compartment, locating the sensor in a spot typical of the average ambient temperature (e.g., in front of the blower on the ceiling in the center of the room). Secure the probe with the provided 3/8" clamp.
- Bring AC power (110VAC standard, 220VAC optional) through suitable conduit to the hole in the top of the enclosure. Connect to the black & white #18 wires located in the small compartment above the alarm unit, insulating the splice and tucking the wires away.
Warranty:
All systems and components manufactured by Modularm Corporation are warranted to be free from defects in material and workmanship under normal use and service for one year from the date of installation. Modularm agrees to repair or replace defective systems or components. This warranty does not apply to altered or repaired systems by unauthorized representatives. Modularm Corporation's sole liability is limited to repair or replacement of its manufactured components.
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