Gas detectors Riken Keiki

The world’s smallest 4-gas monitor

gx 35 and the gx 3r pro

Weighing only 99.79 grams, it clips comfortably within a worker’s breathing zone. Both the GX-3R and the GX-3R Pro utilize a new generation of micro sensors:

  • The new LEL sensor has two active filaments to increase its resistance to silicone poisoning
  • The new O2 sensor has a 3 to 5 year life span
  • H2S and CO are now monitored by one combination micro-sensor
  • Available with a hydrogen compensated CO sensor (as LEL/O2/CO)
  • Non-compliance indicator
  • The sensors are field replaceable: Easy to change in less than 60 seconds

Weighing only 129.84 grams, it fits in the palm of your hand! In addition to the four confined space gases (CO, H2S, LEL, O2) the GX-3R Pro has a 5th channel for toxic and infrared sensors that can monitor:

GX-3R Four Gas Monitor callouts

  • ppm of CO2
  • % volume of CO2
  • SO2
  • CO sensor (with hydrogen compensation)
  • HCN, NO2, NH3, or CL2

Additionally, the GX-3R Pro comes equipped with:

  • Two interchangeable sensor slots providing flexible configurations
  • Non-compliance indicator
  • Man-down alarm
  • Panic alarm

gx 32 bluetooth tool

Stay Connected!

The GX-3R Pro has Bluetooth Connectivity

  • Connect to the RK Link app to view direct instrument readings
  • Adjust alarms and instrument settings
  • Configure it to send alarm notifications and location to your desired contacts in case of emergency
  • Available on iOS and Android

OSHA defines the breathing zone as a ten inch radius around the worker’s nose and mouth, and requires that worker exposure monitoring air samples be collected in the breathing zone. Air sampling filters may be attached to the collar or lapel.  Traditionally this means only a single gas monitor would be small enough for a worker to practically wear a gas monitor ‘In the breathing zone’. Now there is a 4 gas monitor smaller than many single gas monitors.

The GX-3R is the worlds smallest 4 gas monitor weighing only 99.79 grams and can comfortably be clipped within a worker’s breathing zone. It simultaneously monitors and displays LEL combustibles, O2, CO (Hydrogen compensated CO also available), and H2S.

The GX-3R represents the latest evolution of gas detection technology utilizing a new generation of micro sensors. The LEL sensor has a unique design with two active filaments in one sensor to increase it’s resistance to silicone poisoning. If one filament gets poisoned the second filament takes over. The new O2 sensor is electro chemical with a 3 to 5 year life span.  H2S and CO are now available in a combo micro sensor.  

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.

Gas Detected (CO)
H2 Compensated
Carbon Monoxide(CO) Hydrogen Sulfide(H2S) H2S
Combustible Gases
(Methane as standard)
Dual Sensor
Sensor Slot 1 2
EC Dual EC EC Catalytic combustion
Detection Range
0 ~ 2,000 ppm
(1 ppm)
0 ~ 200.0 ppm
(0.1 ppm)
0 ~ 100% LEL
(1% LEL)
0 ~ 40% Vol. (0.1%)
± 5% of reading
or ± 2 ppm CO
± 5% of reading
or ± 5 ppm CO
(whichever is greater)
± 5% of reading
or ± 2 ppm H2S
(whichever is greater)
± 5% of reading
or ± 2% LEL
(whichever is greater)
± 5% of reading O2
Sampling Method Diffusion sampling standard (hand aspirator or clip-on motorized pump optional)
Display Digital LCD displays with 7 segment plus 14 segment plus icon
Preset Alarms
(User Adjustable)
Over scale alarm
1st alarm: 25.0 ppm
2nd alarm: 50.0 ppm
3rd alarm: 1200.0 ppm
TWA alarm: 25.0 ppm
STEL alarm: 200.0 ppm
Over alarm: 2000.0 ppm
1st alarm: 5.0 ppm
2nd alarm: 30.0 ppm
3rd alarm: 100.0 ppm
TWA alarm: 1.0 ppm
STEL alarm: 5.0 ppm
Over alarm: 200.0 ppm
1st alarm: 10% LEL
2nd alarm: 25% LEL
3rd alarm: 50% LEL
Over alarm: 100% LEL
Types of Alarms Gas Alarm: 3 Increasing alarms, STEL, TWA, overscale alarm. O2 decreasing/increasing.
Trouble alarm: Sensor disconnection, low battery, circuit error, calibration range error
Display of Alarm Gas 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 Time Within 30 seconds (T90)
Power Source Lithium-ion battery, Approx. 25 hours after a 3 hour full charge
Approvals ATEX, CSA
& Weight
2.2” 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 Material Explosion proof, dust and water resistant to IP-66/68 (2m,1h) approval. Drop height 23 ft
Controls Two buttons: POWER / MODE, AIR
Data logging Logs user ID, station ID, Calibration & Bump Test history, Alarm Events & Alarm Interval Trends
Alligator clip, protective rubber boot, charger, and calibration adapter
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 data logger

The world’s smallest 4-gas monitor

Category Portable Gas Detector
Type Multi gas
Detection gas HC or CH4 / O2 / CO / H2S
Principle of detection Catalytic Combustion Potentiostatic Electrolysis
Detection range 0-100%LEL (HC/CH4)
0-40vol% (O2)
0-2000ppm (CO)
0-200ppm (H2S)
Sampling method Diffusion
Display of alarm Flashing light / buzzer / vibration
Explosion protected construction Intrinsically safe
Explosion-proof class IECEx : Ex da ia IIC T4 Ga / Ex da ia I Ma (With combustible gas sensor)
Ex ia IIC T4 Ga / Ex ia I Ma (No combustible gas sensor)
ATEX : II1G Ex da ia IIC T4 Ga / IM1 Ex da ia I Ma (With combustible gas sensor)
II1G Ex ia IIC T4 Ga / IM1 Ex ia I Ma (No combustible gas sensor)
IP rating IP66/68
Approvals IECEx / ATEX / INMETRO / Japan EX / CE
Power source Lithium ion rechargeable battery unit
Battery life Approx. 40 hours after full charge (with long battery mode)
Dimensions Approx. 58 (W) x 65 (H) x 26 (D) mm
Weight Approx. 100g
Operating temperature range -40℃ to +60℃ (no sudden changes)
Operating humidity range 0 to 95%RH (no condensation)