RKI Instruments GX-3R Confined Space 4 Gas Personal Gas Detector 72-RA-C

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RKI Instruments

GX-3R Confined Space 4 Gas Personal Gas Detector 72-RA-C

The GX-3R is the worlds smallest 4 gas monitor weighing only 3.52 ounces and can comfortably be clipped within a worker’s breathing zone (2.2” W x 2.55” H x 1.02” D). It simultaneously monitors and displays LEL combustibles; O2; CO (Hydrogen compensated CO also available); and H2S.


  • Simultaneous detection of 4 gases.
  • Smallest & lightest 4 gas monitor.
  • Simple 2-button operation.
  • Non-Compliance Indicator.
  • Alarms: audible; visual; & vibration.
  • 3 user adjustable alarm levels.
  • Impact resistant body with removable rubber boot.
  • Large LCD Auto-backlit display.
  • 25 hours of operation (Lithium-ion battery).
  • Field replaceable sensors & filters.
  • Water and dust resistant design; IP66/68.
  • 3 Year warranty.


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


Gas Detection Specifications (Part 1)
Gas DetectedSensor SlotDetection Principle
(CO) H2 Compensated1EC
Carbon Monoxide (CO)1Dual EC
Hydrogen Sulfide (H2S)1Dual EC
H2S Only1EC
Combustible Gases (Methane as standard)2Catalytic combustion
Gas Detection Specifications (Part 2)
Gas DetectedDetection Range (Increments)Accuracy Statement
(CO) H2 Compensated0 ~ 2;000 ppm (1 ppm)± 5% of reading or ± 2 ppm CO
Carbon Monoxide (CO)0 ~ 2;000 ppm (1 ppm)± 5% of reading or ± 5 ppm CO (whichever is greater)
Hydrogen Sulfide (H2S)0 ~ 200.0 ppm (0.1 ppm)± 5% of reading or ± 2 ppm H2S (whichever is greater)
H2S Only0 ~ 200.0 ppm (0.1 ppm)± 5% of reading or ± 2 ppm H2S (whichever is greater)
Combustible Gases (Methane as standard)0 ~ 100% LEL (1% LEL)± 5% of reading or ± 2% LEL (whichever is greater)
Oxygen0 ~ 40% Vol. (0.1%)± 5% of reading O2
General Specifications
Sampling MethodDiffusion sampling standard (hand aspirator or clip-on motorized pump optional).
DisplayDigital LCD displays with 7 segment plus 14 segment plus icon.
Preset Alarms (User Adjustable) Overscale Alarm (Non-Adjustable)
1st alarm: 25.0 ppm2nd alarm: 50.0 ppm3rd alarm: 1200.0 ppmTWA alarm: 25.0 ppmSTEL alarm: 200.0 ppmOver alarm: 2000.0 ppm
1st alarm: 5.0 ppm2nd alarm: 30.0 ppm3rd alarm: 100.0 ppmTWA alarm: 1.0 ppmSTEL alarm: 5.0 ppmOver alarm: 200.0 ppm
1st alarm: 10% LEL2nd alarm: 25% LEL3rd alarm: 50% LELOver alarm: 100% LEL
Types of AlarmsGas Alarm: 3 Increasing alarms; STEL; TWA; overscale alarm. O2 decreasing/increasing.
Trouble Alarm: Sensor disconnection; low battery; circuit error; calibration range error.
Display of AlarmGas Alarm: Flashing LEDs; continuous buzzer (100 db @ 30 cm); flashing gas value; vibration.
Trouble Alarm: Flashing LEDs; intermittent buzzer (95 db @ 30 cm); display of error message.
Operating Temp. & Humidity-20°C ~ +50°C [ -4°F ~ +122°F ]; 10 to 90% RH; non-condensing (continuous environment).
-40°C ~ +60°C [ -40°F ~ +140°F ]; 0 to 95% RH; non-condensing (temporary environment; 15 minutes).
Response TimeWithin 30 seconds (T90)
Power SourceLithium-ion battery; Approx. 25 hours after a 3 hour full charge.
ApprovalsATEX; CSA
Dimension & Weight2.2” W x 2.55” H x 1.02” D (Approx. 58 W x 65 H x 26 D mm); 3.52 ounces (approx. 100 g) without rubber booth.
2.4” W x 2.63” H x 1.06” D (Approx. 61 W x 67 H x 27 D mm); 3.70 ounces (approx. 105 g) with rubber booth.
Case MaterialExplosion proof; dust and water resistant to IP-66/68 (2m;1h) approval. Drop height 23 ft.
ControlsTwo buttons: POWER / MODE; AIR
DataloggingLogs user ID; station ID; Calibration & Bump Test history; Alarm Events & Alarm Interval Trends.
WarrantyThree years material and workmanship.
Standard Accessories• Alligator clip
• Protective rubber boot
• A/C Charger
• Calibration Adapter
Optional Accessories• SDM-3R calibration station
• RP-3R Clip-on sampling pump with 4” rubber nipple; 10’ hose and probe (up to 40’ hose available)
• Padded carrying case for GX-3R and accessories
• USB to IrDA downloading cable for datalogger
More Information
Shipping Weight 0.50