The Level Alarm is a Thermistor Sensor, 9V battery or AC-powered with battery-backed portable device designed for monitoring liquid nitrogen levels in various tanks and storage units. Its 9V battery-only operating mode allows flexible placement where AC power isn’t available.
Optimized for high-efficiency cryogenic Dewars and storage tanks, it ensures accurate monitoring of gradual level changes. The 9V battery backup maintains operation during AC power outages, while remote alarm contacts enable integration with existing systems for added security.
SENSOR: A 2-meter thermistor-type sensor is used for reliable cryogenic liquid detection. The sensor features:
- Teflon-jacketed twisted wire for durability and flexibility
- Cryogenic compatibility, maintaining flexibility even at extremely low temperatures
- Proven performance, with over 50 years of successful use in cryogenic applications
The thermistor remains a trusted and time-tested solution for accurate liquid level detection in demanding environments.
CONTROL FEATURES: The TEST button simulates a LOW level alarm condition, activating the LED and audible indicators. If AC power is available, the REMOTE contacts will change state, confirming proper function. The unit continuously monitors with no delay when powered by AC. The REMOTE contacts also respond to alarm conditions, including low 9V battery indication, ensuring timely battery replacement for reliable backup power during outages
ALARM: The audible and visual alarm activates when the sensor is above the cryogenic liquid, sensor is unplugged, shorted, or has a broken wire. Normal operation resumes once a functional probe is connected.
When operating on 9V battery power, pressing the TEST button “wakes” the unit from the power-saver mode. This initiates a 3.5 minute continuous monitoring sequence. Repeated pressing of the TEST button activates the alarms and will noticeably shorten battery life.
BATTERY LIFE & LOW-BATTERY INDICATION: When operating on a 9V battery (no AC power), the device provides up to 9 months of monitoring thanks to a proprietary power-saving mode during non-alarm conditions.
- Alarm events disable power-saving, reducing battery life. A continuous alarm can drain a new battery in ~72 hours.
- After any alarm without AC power, battery replacement is recommended.
A low-battery alert triggers audible chirps and LED flashes when voltage drops below safe levels. This alert resets automatically with battery replacement. Battery status is also monitored during AC-powered operation to ensure backup readiness.
REMOTE ALARM CONTACTS: The system includes relay contacts (SPDT 1A @ 125VAC / 0.5A @ 24VDC) for remote alarm monitoring. These contacts will change state in response to any alarm condition, including LOW liquid-level, low battery, or AC power loss. Dry contacts can be integrated with a Building Monitoring System (BMS), PLC, or other monitoring platforms to notify remote personnel when an alarm is triggered.
– SPECIFICATIONS –
Power Requirements:
Input Voltage: AC100-250VAC @ 50/60hz & 9-volt DC / Battery
Battery Type: Energizer Lithium L522*
Battery Ahr 750mAhr
* Or equivalent 9V battery
Input Current (average): 80uA (720uW)
Alarm (max): 11mA
Monitoring (typical): 630uA (3.5min)
Power-Saver (typical): 46uA (40min)
Power management:
Monitoring mode: 3.5 minutes
Power-Saver mode*: 40 minutes
*Alarm & TEST de-activate power-saver mode timers
Battery Life: (Energizer L522)
Alarmed (constant): ~68hr’s
Monitoring (no alarm): ~280 days
Sensor Type: Thermistor (2m length wire)
Dimensions (L x W x H):
Inches: 3 1/4” x 1 1/2” x 4 3/8”
Metric: 8.3cm x 3.8cm x 11.1cm)
Weight: 7 oz. / 196g (including battery)
Download: OPERATIONS MANUAL / INSTRUCTION FOR USE
OP-MANUAL_9v-AC-alarm_w-remote
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