GX-3R Pro

General Information:

The GX-3R Pro is the world’s smallest 5-gas monitor weighing only 4.58 ounces and fits in the palm of your hand (2.9” W x 2.6” H x 1.06” D). It simultaneously monitors and displays 5 different gases. In addition to monitoring standard confined space gases, LEL, O2, CO, & H2S, the GX-3R Pro has a 5th channel where you can add infrared or toxic sensors. Two of the four sensor slots have interchangeable sensors providing flexible configurations, which can easily be changed in the field. The GX-3R Pro comes equipped with Bluetooth wireless communication, man-down alarm, the choice of alkaline or rechargeable power supply, and a 3 year warranty. The Lithium-ion battery pack will operate for 25 hours and will fully charge in 3 hours. The GX-3R Pro utilizes Bluetooth communication to display direct gas readings from the instrument to a phone app, which is available free on either iOS or Android phones. Automatic notifications can be programmed to send text or email messages, if there is an alarm event from the GX-3R Pro. Safety supervisors will appreciate the non-compliance indicator. The instrument flashes it’s 3 LED lights every 30 seconds in the following conditions; if the instrument has not been bump tested, or if calibration is due, or if there was a gas alarm event. The 3 LED lights will continue to flash once every 30 seconds until the non-compliance condition has been resolved. The 30 second interval is adjustable.


  • Smallest & lightest 5 gas monitor 2.9″ W x 2.6″ H x 1.06″ D , 4.58 ounces
  • Simultaneous detection of 5 gases LEL, O2, H2S, CO, and other optional sensors H2 Compensated CO sensor available
  • Simple 2-button operation
  • Bluetooth communication with iOS & Android App
  • Non-Compliance Indicator
  • 3 user adjustable alarm levels
  • Panic Alarm
  • Man Down Alarm
  • Impact resistant body
  • Large full dot, auto-backlit display with auto-rotation
  • Stealth mode for law enforcement
  • Field replaceable sensors & filters
  • Water and dust resistant design, IP66/68
  • 3 Year Warranty
  • Applications

    • Personal monitoring
    • Confined spaces
    • Refineries/petrochemical
    • Utilities
    • Oil and Gas
    • Water/Wastewater
    • Fire Services
    • Law Enforcement
    • Construction

    Standard Sensor Settings for the GX-3R Pro

    Sensor Type Calibration Gas Value Warning Alarm Low Alarm High Alarm TWA Alarm STEL Alarm Part Number
    H2S - Hydrogen Sulfide 25ppm Hydrogen Sulfide 5ppm 30ppm 100ppm 1ppm 5ppm ESR-A13i-H2S
    CO - Carbon Monoxide 50ppm Carbon Monoxide 25ppm 50ppm 1200ppm 25ppm 200ppm ESR-A13P-CO
    LEL - Methane Curve 50% LEL 10% LEL 25% LEL 50% LEL N/A N/A NCR-6309
    O2 - Oxygen 12% Oxygen 19.5% 18.0% 23.5% N/A N/A ESR-X13P-OXY

    Exotic Sensor Settings for the GX-3R Pro

    Sensor Type Calibration Gas Value Warning Alarm Low Alarm High Alarm TWA Alarm STEL Alarm Part Number
    NH3 - Ammonia 25ppm Ammonia 25ppm 35ppm 300ppm 25ppm 35ppm ESR-B134-NH3
    Cl2 - Chlorine 5ppm Chlorine 1ppm 2ppm 10ppm 0.5ppm 1ppm ESR-B136-CL2
    HCN - Hydrogen Cyanide 10ppm Hydrogen Cyanide 5ppm 10ppm 30ppm 4.7ppm 10ppm ESR-A13D-HCN
    PH3 - Phosphine 0.5ppm Phosphine 0.3ppm 0.6ppm 1ppm 0.3ppm 1ppm ESR-A13D-PH3
    NO2 - Nitrogen Dioxide 10ppm Nitrogen Dioxide 2ppm 4ppm 20ppm 0.5ppm 1ppm ESR-A13D-NO2
    SO2 - Sulfur Dioxide 5ppm Sulfur Dioxide 2ppm 5ppm 100ppm 2ppm 5ppm ESR-A13D-SO2