Infrared Combustible Gas Sensor Module 5100-28-IT

Sierra Monitor’s infrared fixed gas sensor, the 5100-28-IT, monitors combustible gases such as Methane and Propane, detecting and alarming users when gases reach between 0 to 100% lower explosive limit (LEL) concentrations.

The 5100-28-IT module is based on infrared (IR) technology, an accurate and stable method of detection that requires low maintenance and can operate in high combustible gas and/or low oxygen environments.

As the industry-wide top choice network-enabled fixed gas sensor, the FM-approved 5100-28-IT module utilizes Non-Dispersive Infrared technology to monitor for combustible gases. This technology also allows the module to rapidly recover after exposures to high concentrations of hydrocarbon gas and operate in environments where catalytic bead poisons might exist. The module also has minimal maintenance requirements and only requires one year calibration intervals. Although the 5100-28-IT module can be used as a stand-alone sensor, it can also be used as a 4-20 mA component or as a Modbus RTU node. For higher level system capability, the module can interface directly to Sierra Monitor’s Sentry IT Controller to enable system level Modbus serial communications, area and zone alarm management, extensive system diagnostic features, WebServer interface, and multiplexing sensor connections.

The fixed Infrared Combustible Gas Sensor Module 5100-28-IT is approved and certified by a variety of third party agencies, including UL, FM, SIL-2, ATEX, CSA, and ABS. These approvals and certifications assure our customers that we carry only the highest quality of products.


The 5100-28-IT supports GlobalCal™, our unique global calibration feature of the Sentry IT Controller. This allows a single technician to calibrate connected detectors from the Sentry IT Controller. With GlobalCal, the calibration happens at the controller level. Multiple sensors can be connected to a single controller, allowing groups of sensors to be calibrated at the same time. Standard gas is applied remotely, using permanently installed tubing, rather than direct delivery to the fixed gas detector.

Combined with the one-year calibration interval, GlobalCal reduces labor costs associated with calibration. The need to shut down active process areas for calibration consequently costs facilities thousands of dollars in lost production time. GlobalCal, with its remote and non-intrusive methods, allows production to continue during the calibration process, thus avoiding the costs of lost production. In addition, factory-authorized service technicians performing gas detector calibration save time and costs by remotely calibrating all gas detectors at once from the Sentry IT Controller.

Infrared Combustible Gas Sensor Module 5100-28-IT

  • GlobalCal™ support – Non-intrusively calibrate all connected sensors at the same time without declassifying the area
  • Menu-driven system – Rapidly adjust user-friendly configuration of alarm setpoints, calibration, maintenance, and alarm acknowledgment
  • Integral LED Display – Easily calibrate and access gas concentrations, relay statuses, and diagnostics
  • 1 Year Calibration Interval – Dramatically reduce maintenance and operating costs for the user
  • Internal Continuous Self-Diagnostics – Automatically indicate any fault or optics problems
  • Network compatible with Modbus, 4-20mA, HART, relay interface – Easily install in a variety of field applications and easily obtain critical safety information wherever needed
  • Modbus RTU Serial Interface – Provide an easy interface to the world's most common industrial protocol
  • SMC Sentry Digital Bus Interface – Connect easily with existing Sentry systems that have been in operation for many years
  • Stainless Steel 316 or Epoxy-Coated Aluminum enclosures   Meet specific installation needs with different enclosure materials

Specifications for Infrared Combustible Gas Sensor Module 5100-28-IT

Model Number

  • 5100-28-IT

Sensor Type

  • Infrared, Dual Wavelength


  • Dual Range:
  • Default: 0-100% LEL Methane
  • User Setting: 0-100% by vol. Methane
  • Repeatability: +/- 1% LEL
  • Accuracy:
    • +/- 1% for 0-50% LEL range
    • +/1 2% for 51-100% LEL range
  • Zero Drift: +/- 1% full scale per month @ 20 oC (68oF) ambient (max +/- 3% full scale per year)
  • Sensor Life: Typically >5 years
  • Heated Sensor: Heated cell to prevent condensation
  • Response Time: T90 < 10 sec*


  • Display: Fixed and scrolling LED
  • Signal Outputs:
    • Sentry digital bus
    • Analog 4-20 mA Linear
      • 3-wire Non-Isolated
      • 4-wire Isolated
    • Serial RS-485 Modbus RTU
  • Relay: Optional


  • Relays:
    • 5 amp Alarm, Warning (0.25 amp Trouble)
    • 5A @ 250 VAC, 5A @ 30 VDC (Alarm, Warning)
    • Board includes auxiliary connection for Sentry multiplexing
  • HART: Termination board includes HART, Modbus RS-485, 4-20mA, Digital Input, 2A Relay output, No Sentry bus
  • Remote Sensor: Up to 100 feet (30.4m)


  • Power consumption: 3 watts
  • Input voltage: 24 VDC nominal: 10-30 VDC

Operating Range

  • Ambient Temperature Range: -40o to 140oF (-40o to 60oC)
  • Relative Humidity: 0-99% Non-Condensing


  • Dimensions: (H x W x D)
    •  A1 & A2: 7.8 x 5.7 x 3.9 in. (19.8 x 14.5 x 9.9 cm)
    • S1 & S2: 7.5 x 4.4 x 4.9 in. (19 x 11 x 12 cm)
  • Weight:
    • A1 & A2: 3.4 lb. (1.5 Kg)
    • S1 & S2: 7.2 lb. (3.3 Kg)
  • Enclosure: Epoxy coated aluminum or 316 stainless steel
  • Housing: AL or SS (same as enclosure)
  • Hazardous Area Classification:
    • Explosion proof, Class 1, Div. 1, Groups C, D
    • Class I, Zone 1
    • Group IIC, IP66, IP65, NEMA 4X, T6
    • TA = -40oC to 85oC II2 GD, Ex d IIC
  • Warranty: 2 years


  • UL-2075: Performance Approved
  • ATEX II G, Ex d IIB+H2 T6 Gb, Ta = -20 oC to 60oC
  • FM Approval 6320: Combustible Gas Detector Performance
  • FM Approval 3600: Class I Div. 1, Groups C, D
  • SIL-2 Certified: Certified by Lloyd’s Register (IEC 61508)
  • CSA: For enclosure in hazardous locations
  • ABS: Certificate of Compliance
  • CCCF/CQST: Certificate for China
  • CCOE/PESO: Certificate for India

How to Purchase the Infrared Combustible Gas Sensor

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