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Overview
Worker adoption is the single most common failure point in personal gas monitoring programmes. A device that is worn correctly and consistently provides genuine protection. A device that is clipped to a bag, left in a pocket, or simply not worn because it’s uncomfortable or inconvenient provides none. For safety managers who have dealt with this problem — and most have — the GX-3R addresses it at the source.
The Riken Keiki GX-3R Multi Gas Detector is the world’s smallest 4-gas personal monitor. At 100g without the rubber boot — approximately the weight of a smartphone — and measuring just 58×65×26mm, it is small enough to be comfortably worn in the breathing zone on a shirt collar clip throughout an entire shift without the worker noticing it. It simultaneously monitors combustible gas (LEL), oxygen (O2), carbon monoxide (CO, with hydrogen-compensated variant available), and hydrogen sulfide (H2S), with three-level alarm thresholds, TWA and STEL monitoring, and 25 hours of continuous runtime from a 3-hour charge.
What makes the GX-3R exceptional in this category is not just the size — it’s that the size is achieved without compromising on the specifications that matter for professional deployment. ATEX, IECEx, CSA, and MED certification. IP66/68 ingress protection. 23-foot drop resistance. Comprehensive datalogging including calibration and bump test history. A 3-year manufacturer warranty. These are not the specifications of a miniaturised consumer product; they are the specifications of a full industrial-grade personal monitor that also happens to be the smallest available in its class.
Key Features
World’s Smallest 4-Gas Monitor — 100g, 58×65×26mm
The GX-3R’s dimensions are genuinely remarkable for a full-featured 4-gas personal monitor: 2.2″ wide, 2.55″ tall, and just over 1″ deep. At 100g without the rubber boot, it weighs less than most mobile phones. It clips directly into the breathing zone on a shirt collar or lapel without pulling the fabric or creating discomfort during physical work. For operations where consistent device wear is a challenge — particularly in physically demanding roles, hot environments, or workforces with high turnover — a device this small and light removes the primary practical barrier to consistent adoption.
Simultaneous CO, H2S, LEL, and O2 Detection
The GX-3R monitors all four standard gas hazard categories simultaneously: carbon monoxide (0–2,000 PPM), hydrogen sulfide (0–200 PPM), combustible gases (0–100% LEL), and oxygen (0–40% VOL). All four readings are displayed simultaneously on the digital LCD — no channel switching, no display cycling. A hydrogen-compensated CO variant is available for environments where hydrogen cross-interference with standard CO sensors is a concern — particularly relevant in battery charging rooms, fuel cell facilities, and hydrogen handling environments.
Three-Level Alarm System with TWA and STEL Monitoring
The GX-3R provides three independently adjustable gas alarm thresholds per channel, plus TWA (Time-Weighted Average) and STEL (Short-Term Exposure Limit) alarms, an overscale alarm, and trouble alarms for sensor disconnection, low battery, circuit error, and calibration range error. Three increasing alarm levels allow graduated response protocols — first alarm for awareness, second for action, third for immediate evacuation — supporting sophisticated confined space entry and industrial hazard response procedures. TWA and STEL monitoring tracks cumulative and short-term occupational exposure against regulatory limits for formal health surveillance programmes.
100dB Alarm with LED Flash and Vibration
Gas alarms trigger a 100dB continuous buzzer, flashing LED indicators, flashing gas value display, and vibration simultaneously. The 100dB alarm level is specified at 30cm — the distance relevant for a breathing zone-mounted personal monitor — ensuring the alarm is loud enough to be heard by the wearer in industrial noise environments. Vibration alarm provides additional tactile notification when hearing protection is worn or audible alarms may be masked. Trouble alarms use a 95dB intermittent buzzer with error message display for immediate diagnostic notification.
IP66/68 (2m, 1h) and 23-Foot Drop Resistance
The GX-3R with rubber boot achieves IP66/68 dual ingress protection — fully dust-tight and rated for water submersion to 2 metres for 1 hour. Combined with a 23-foot (7m) drop resistance specification, this represents an exceptional durability standard for a 100g personal monitor. For industrial field operations where instruments are exposed to rain, water spray, accidental immersion, and the drops and impacts of daily field use, the GX-3R’s ingress and drop protection specifications are considerably more robust than most comparable personal monitors in this size class.
25-Hour Battery Life from a 3-Hour Charge
A lithium-ion battery provides approximately 25 hours of continuous operation after a 3-hour full charge. The 25-hour runtime covers multiple consecutive 8-hour shifts from a single overnight charge — or an extended 24-hour operational period for emergency response and marine watch-keeping applications. For shift-based operations where devices are charged overnight and deployed across a full working day, the 25-hour runtime provides a meaningful safety margin against incomplete charging that a standard 8–12 hour device cannot offer.
Comprehensive Datalogging — User ID, Station ID, Calibration and Bump Test History
The GX-3R logs user ID, station ID, calibration and bump test history, alarm events, and alarm interval trends. This is a more detailed datalog specification than most personal monitors provide — user and station ID logging means exposure data is attributed to both the person wearing the device and the location they were monitoring, providing a complete operational record for permit-to-work documentation, incident investigation, and occupational health surveillance. USB to IrDA downloading cable (optional) provides PC data transfer for reporting and records management.
Optional Clip-On Motorised Sampling Pump
An optional RP-3R clip-on motorised sampling pump with 4-inch rubber nipple, 10-foot hose, and probe (up to 40-foot hose available) converts the GX-3R from a diffusion personal monitor into a pump-equipped survey instrument for confined space pre-entry assessment. This optional upgrade means a single GX-3R can serve as both the pre-entry survey instrument and the personal monitor worn during entry — with the pump removed after pre-entry assessment and the diffusion monitor continuing during the entry itself.
Technical Specifications
Model: Riken Keiki GX-3R
Target Gases: CO (or H2-compensated CO), H2S, LEL (combustible), O2
CO Range: 0–2,000 PPM (1 PPM increments)
H2S Range: 0–200 PPM (0.1 PPM increments)
LEL Range: 0–100% LEL (1% LEL increments)
O2 Range: 0–40% VOL (0.1% increments)
Display: Digital LCD (7-segment + 14-segment + icon)
Battery: Lithium-ion, approx. 25 hours after 3-hour full charge
Weight: 100g (without rubber boot) / 105g (with rubber boot)
Dimensions: 58×65×26mm (without boot) / 61×67×27mm (with boot)
IP Rating: IP66/68 (2m, 1h)
Drop Resistance: 23 feet (approx. 7m)
Alarm Types: 3-level gas alarm + TWA + STEL + overscale + trouble alarms | Sound (100dB), LED flash, vibration
Response Time: Within 30 seconds (T90)
Sampling Method: Diffusion (standard) / Optional clip-on pump (RP-3R)
Safety Approvals: ATEX, IECEx, CSA, MED
Operating Temperature: -20°C to +50°C continuous / -40°C to +60°C temporary (15 min)
Data Logging: User ID, station ID, calibration & bump test history, alarm events, alarm interval trends
Warranty: 3 years (material and workmanship)
Benefits
Workers actually wear it — all shift, every shift. At 100g and pocket-size, the GX-3R is the personal gas monitor least likely to be left behind, clipped to a bag instead of a collar, or taken off mid-shift because it’s uncomfortable. For safety managers who have dealt with adoption compliance challenges, a device this small changes the practical equation.
25 hours from a 3-hour charge — no mid-shift battery anxiety. The 25-hour runtime from a 3-hour overnight charge means the device is always ready for a full shift — and then some. For operations running extended shifts, double shifts, or 24-hour emergency response deployments, the runtime provides operational flexibility that 8–12 hour battery alternatives cannot match.
Three-alarm levels support formal graduated response protocols. Three independently adjustable alarm thresholds per gas channel allow safety managers to implement first alarm/second alarm/evacuation protocols that match their specific site emergency response procedures — rather than adapting procedures to the limitations of a single-threshold device.
User and station ID datalogging for complete occupational exposure records. Logging both the user and the monitoring station location for every alarm event and monitoring period provides the granular exposure attribution that formal health surveillance programmes require. For confined space entry permit systems, the combination of user ID, station ID, and alarm interval trends creates a complete entry record in a single instrument.
Optional pump upgrade converts the same device into a pre-entry survey instrument. The RP-3R clip-on pump option means one GX-3R covers both the pre-entry confined space assessment and the personal monitoring during entry — eliminating the need and cost of maintaining separate survey and personal protection instruments for the same confined space entry programme.
3-year warranty — the longest in this class. A 3-year material and workmanship warranty from Riken Keiki provides procurement confidence and total cost of ownership assurance that is meaningfully better than the 1–2 year warranties standard on competing personal monitors. For procurement managers comparing 5-year fleet deployment costs, the 3-year warranty is a direct cost factor alongside unit price and sensor replacement schedules.
Who It’s For
The Safety Manager Whose Biggest Challenge is Getting Workers to Wear Their Monitors
You’ve tried enforcing monitor wear through policy, training, and observation — and it still doesn’t happen consistently. Workers leave heavier, bulkier devices in their vehicles, clip them to tool belts away from the breathing zone, or take them off mid-shift. The GX-3R at 100g, clipped in the breathing zone on a collar, is simply not a burden — and a device that isn’t a burden gets worn. That’s the problem the GX-3R solves for your programme.
The Confined Space Supervisor Managing Pre-Entry and Entry Monitoring
You run a formal confined space entry programme with pre-entry atmospheric assessment and continuous personal monitoring during entry. You need devices that cover all four standard gas hazard categories, support three-alarm level graduated response protocols, provide datalogging for permit documentation, and can optionally be upgraded with a pump for pre-entry survey use. The GX-3R with optional RP-3R pump covers your entire programme from pre-entry through to post-entry record documentation in a single device family.
The Marine Safety Officer or Offshore Inspector
You conduct confined space entry work on board vessels and offshore platforms where MED certification is required alongside ATEX/IECEx, IP68 protection is a practical necessity given deck and hold conditions, and the H2-compensated CO variant is relevant for battery room and fuel cell monitoring on modern vessels. The GX-3R’s quad certification (ATEX, IECEx, CSA, MED), IP66/68 rating, 23-foot drop resistance, and H2-compensated CO option address your specific marine deployment requirements in the smallest available device footprint.
Possible Applications
- Personal monitoring in classified hazardous areas — Continuous CO, H2S, LEL, and O2 personal protection for workers in refineries, chemical plants, and petrochemical facilities
- Confined space entry programmes — Pre-entry pump assessment (with optional RP-3R) and continuous personal monitoring during tank, vessel, manhole, and underground structure entry
- Marine vessel and offshore platform work — MED-certified personal monitoring for vessel crew, marine surveyors, and offshore workers with H2-compensated CO option for battery and fuel cell areas
- Water and wastewater treatment — Personal H2S, CO, O2, and LEL monitoring for workers in underground pump stations, treatment tanks, and sewer infrastructure
- Fire services and hazmat response — Personal atmospheric protection for first responders at incident scenes with unknown gas hazards
- Construction and civil engineering — Personal gas monitoring for workers in trenches, underground construction, and enclosed building work areas with gas hazard risk
- Utilities and infrastructure maintenance — Personal monitoring for field technicians maintaining gas distribution, electrical, and water utility infrastructure with confined space exposure risk
- Occupational exposure monitoring programmes — TWA and STEL data collection for workers with chronic gas exposure risk in chemical, pharmaceutical, and industrial manufacturing
Trust and Certifications
ATEX — European Explosive Atmosphere Certification
ATEX certification confirms the GX-3R meets the European standard for personal protective equipment used in explosive atmospheres — required for deployment on EU and UK sites with formal ATEX zone classifications. For the smallest 4-gas monitor available to carry full ATEX certification, this represents a meaningful achievement in miniaturised instrument design.
IECEx — International Hazardous Area Recognition
IECEx certification provides internationally recognised hazardous area approval accepted across 50+ countries including Australia, the Middle East, and Asia-Pacific. For workers and contractors operating across international industrial markets, IECEx removes the need for separate national certifications in most jurisdictions.
CSA — North American Certification
CSA (Canadian Standards Association) certification provides North American hazardous location approval — required for deployment in US and Canadian industrial facilities under NEC/CEC hazardous area classifications. For organisations with operations or clients in North America, CSA certification is the site access requirement the GX-3R satisfies alongside its European and international approvals.
MED — Marine Equipment Directive
Marine Equipment Directive certification confirms the GX-3R meets the specific safety requirements for gas detection equipment on board ships. For vessel operators and marine inspection contractors where MED certification is a vessel equipment compliance requirement, the GX-3R provides this certification alongside ATEX, IECEx, and CSA — a combination of four international approvals in a single 100g instrument.
IP66/68 (2m, 1h) and 23-Foot Drop Resistance
Dual IP66/68 certification with 2-metre, 1-hour submersion testing and 23-foot drop resistance is a durability specification that significantly exceeds what most personal monitors in this size class provide. For instruments deployed in marine, industrial, and construction field conditions, this protection standard provides genuine confidence in long-term instrument reliability — supported by Riken Keiki’s 3-year warranty.
3-Year Warranty — Riken Keiki Quality Commitment
Riken Keiki is a Japanese precision instrument manufacturer with decades of experience in industrial gas detection — a company whose entire business is built on the performance and reliability of gas detection instruments. The 3-year material and workmanship warranty reflects that manufacturing confidence and provides the longest warranty period available on a standard 4-gas personal monitor in this class.
Authorised by Alright Engineering Solutions
The GX-3R is supplied through Alright Engineering Solutions Pte. Ltd., an authorised distributor of personal and portable gas detection equipment in Singapore. Alright Engineering Solutions provides local procurement support, instrument configuration guidance (standard CO vs H2-compensated CO), and after-sales service for the Singapore and regional market.
Accessories and Variants
RP-3R Clip-On Motorised Sampling Pump (Optional)
Converts the GX-3R from a diffusion personal monitor into a pump-equipped survey instrument for confined space pre-entry assessment. Includes 4-inch rubber nipple, 10-foot hose, and probe — with optional extension to 40-foot hose for deep tank and long-distance sampling. Clip-on design allows the pump to be removed after pre-entry assessment, returning the GX-3R to personal monitor configuration for the entry itself.
SDM-3R Calibration Station (Optional)
Automated single-unit calibration and bump test station for the GX-3R — simplifies calibration and bump test workflows for safety programmes managing multiple devices. Automated calibration station support is particularly valuable for programmes requiring documented calibration records across a fleet, reducing the time and specialist resource required for routine calibration maintenance.
USB to IrDA Downloading Cable (Optional)
Provides PC data transfer for the GX-3R datalogger — downloading user ID, station ID, calibration history, alarm events, and alarm interval trend data for compliance reporting, permit-to-work documentation, and occupational exposure records.
Padded Carrying Case
Protective padded case for the GX-3R and accessories — suitable for transport between sites and storage when the instrument is not in active deployment.
Protective Rubber Boot (Included)
The rubber boot provides additional impact protection and grip for field use. Included as standard — adds minimal size (3mm in each dimension) while improving durability against knocks and drops in industrial field conditions.
Standard CO vs H2-Compensated CO Variants
Standard CO sensor — For standard industrial CO monitoring where hydrogen cross-interference is not a concern
H2-Compensated CO sensor — For environments where hydrogen is present alongside CO — battery charging rooms, fuel cell facilities, hydrogen handling areas, and modern marine vessels with hybrid power systems — where standard CO sensors may produce false readings due to H2 cross-sensitivity
Related Products from Alright Engineering Solutions
GX-8000 Sample Draw Multi Gas Monitor — Full survey instrument for marine and industrial confined space pre-entry assessment
BELL LITE Multi Gas Detector — Alternative personal 4-gas monitor with ATEX certification and BELLCONNECT app
BELLMINI Single Gas Detectors — Personal clip-on monitors for individual gas hazards
K-600M Multi Gas Detector — Pump-equipped multi-gas detector with 20m sampling and 4G for connected safety programmes
Get in Touch
If you’re looking for the smallest, lightest, and most completely certified 4-gas personal monitor available — one that workers will actually wear consistently, that covers every standard certification requirement across industrial, marine, and North American markets, and that comes with the longest warranty in its class — the Riken Keiki GX-3R is worth a serious evaluation.
Contact Alright Engineering Solutions to request a formal quote, discuss standard vs H2-compensated CO configuration, or arrange a hands-on product demonstration for your safety team.
📍 3791 Jalan Bukit Merah #06-01, E-Centre @ Redhill, Singapore 159471
