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Portable Gas Detectors

CO-04 Cost Effective Personal Carbon Monoxide (CO) Monitor

Compact Low Cost Personal Carbon Monoxide (CO) Gas Detector with Long life CO sensor that has 3 year warranty

A portable gas monitor designed to measure Carbon Monoxide. Small and lightweight it is ideal for wearing in the "Breath Zone " around the head without interfering with work. It has 3-alarm levels which can be user set and a replaceable long-life sensor with a 3-year warranty. CO-04 is durable and tough and designed for harsh environments and to deliver many years trouble free operation. 

O4 series general features: 

  • Broad line up 10 models with more to follow. 
  • O2, CO, H2S, SO2, Dual O2 / CO, NH3, NO2, HCN, PH3 and CO-H2 models available now. 
  • CO2, CL2 and %LEL Models 2022. 
  • up to 9000 hours battery life.
  • IP 66/67 rated. 
  • Durable 7-meter drop test. 
  • ATEX. 

Series-04 Personal Single Gas Detectors

Product Features

Personal Single Gas Monitors : Models OX-04, CO-04, HS-04, SC-04 , CX-04

Riken Keiki Model CO-04 Represents the latest iteration of Robust yet cost effective Riken Single gas personal Monitors.

Facilities such as Oil Refineries, Petrochemical Storage Facilities, Water and Wastewater Treatment plants, Pharmaceutical labs, Utilities, Fire fighting and Chemical Plants are hazardous areas. Workers and Visitors need personal gas protection at all times without the addition of extra bulky equipment. Personal Single Gas Monitors are ideal for this.

Cost of Ownership

Disposable gas detectors are low cost but users can suffer high failure rates, this can result in safety concerns.  Users often find the cost of ownership often outweighs the small initial cost saving over a reliable renewable gas detector. Customers constantly have to replace failed units resulting in personnel down time and the lost productivity.

Personal Single Gas Monitors

The Riken Keiki 04 series are personal single gas monitors designed for protection from exposure to, Oxygen Deficiency, Hydrogen Sulfide (H2S), Carbon Monoxide (CO), Sulphur Dioxide ( SO2 ), Hydrogen Cyanide (HCN), Nitrogen Dioxide (NO2), Phosphine (PH3), Ammonia (NH3), Chlorine (CL2) (due 2022) and Carbon Dioxide (CO2) (due 2022). Users of the O4 Series find the units are robust, reliable, long-lasting, and cost effective. In addition they have a digital display, can be calibrated, and are dust and water-resistant (IP-68). The 04-Series has a replaceable rubber boot in addition users can data log from 5 to 300 hours with adjustable intervals.

Personal Single Gas Monitors

The 04 series personal single gas monitors have 3 preset alarms. The user can adjust the alarms to their own levels if desired.  Each version is equipped with visual, audible, and vibration alarms as standard. The replacement sensors are inexpensive. Users can replace the sensors in the field. Customers can expect Sensors to have a life expectancy of 3-5 years in addition they are interchangeable with other Riken Keiki monitors.


Category Portable gas detector
Type Single Gas
Gas type Toxic
Detection gas CO[CO-04]
CO(Reduced H2 interference)[CO-04(C-)]
Principle of detection Electrochemical type
Detection range 0-300ppm / 300-2000ppm
Alarm setpoints 1st 25ppm / 2nd 50ppm / 3rd 1200ppm / TWA 25ppm / STEL 200ppm
Sampling method Diffusion
Display of alarm Flashing light / buzzer / vibration
Explosion protected construction Intrinsically safe
IP rating IP66/67 
Approvals IECEx/ATEX/CE 
Power source AAA alkaline or Ni-MH(eneloop) batteries(x2)
Battery life Approx. 9000hours(AAA alkaline)/Approx. 6000hours(Ni-MH)[CO-04]
Approx. 6200hours(AAA alkaline)/Approx. 4200hours(Ni-MH)[CO-04(C-)]
Dimensions Approx. 54mm(W) x 67mm(H) x 24mm(D)(excluding projections)
Weight Approx. 93g
Operating temperature range -20℃ to +50℃ (no sudden changes)(Approx. 15-minute temporry use environment: -40℃ to +60℃[no sudden changes])
Operating humidity range 10 to 90%RH (no condensation)(Approx. 15-minute temporry use environment: 0 to 95%RH[no condensation])

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