HY-ALERTA™ 5021 Solid-State Area Hydrogen Monitor

H2scan’s HY-ALERTA 5021 solid-state area hydrogen monitor is a reliable, hydrogen gas detector for real-time monitoring of battery rooms that avoids false positives from other gasses. The auto-calibrating technology allows data centers, utilities, telecommunications, and energy storage systems end users to deploy it maintenance-free, with no calibration or board replacements needed throughout the life of the unit. 

The expected service life is 10+ years, making the HY-ALERTA 5021 a low cost of ownership option compared to other technologies. Native Modbus communication from the sensor to a Modbus scanner makes the sensor able to communicate with most existing building management systems and alarm panels. Digital contacts make it easy to connect to exhaust fans to activate during alarm conditions. Multiple mounting options make the HY-ALERTA 5021 perfect for battery rooms, cabinets, and other locations where battery safety is critical.

With no moving parts, the safety monitor is extremely reliable and easy to use. It is intended for use in an air, oxygen, or inert gas background where hydrogen is only occasionally present for short periods, as may occur if there is a leak or off gassing from batteries. The hydrogen detection range is from 4000 ppm to 5% hydrogen, covering 10% to 125% of hydrogen’s lower explosive limit. The monitor can be mounted to the ceiling, wall, or Unistrut for optimal performance.


  • Data Center UPS
  • Telecom Central Offices and Remote Sites
  • Utility Applications and Substations
  • Energy Storage Batteries
  • Vented Lead-Acid Batteries
  • Valve Regulated Lead Acid Batteries
  • Vented Nickel Cadmium Batteries
  • Battery Cabinet Installations

Sensor Specifications

  • Model 5020:
    • Measuring range: 0.4 to 5% (10 to 125% LEL)
    • Time to report 2% is less than 60 seconds when >3% is applied
  • Model 5021:
    • T90 of 5 minutes
    • Time to report 2% is less than 5 minutes when >3% is applied

General Specifications

  • Accuracy: ±0.3% H2Accuracy: ±(0.03 x indication + 0.2)% H2
  • Calibration Interval: None (auto-calibrating)
  • Operating Temperature: -40 to +60°C
  • Storage Temperature: -40 to +85°C
  • Operating Humidity: <95% RH (non-condensing)
  • Usage: Indoor / Outdoor
  • Ingress Protection: IP68
  • Digital Output: RS485, 2-wire; 19200 baud, 8 bit data, 2 stop bits, no parity; Modbus RTU Protocol
  • Analog Output: 4-20 mA available via optional HYAO-1 accessory
  • Input Voltage: 9 – 48 VDC
  • Input Power: 10 W
  • Electrical Connection: M12, 4-pin connector
  • Dimensions: 5.9in (L) x 1.6in (W) x 1.6in (D) (161mm x 40mm x 40mm)
  • Safety Certifications: C/US, CE 0359

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