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    Fixed Oxygen (O2) Gas Detector, 0 to 25% / 30% Vol

    5 out of 5 based on 3 reviews | Write a review
    Fixed gas detector for detecting oxygen concentration. Measuring range 0~25% or 0~30% for selection, output signal 4-20mA and RS485, high accuracy 3% F.S. O2 gas detector has sound and light alarm, real-time display, remote control, small size, lightweight, low price.
    SKU: GD300-O2
    30-day Returns
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    Delivery date: 6-12 days

    Fixed oxygen gas detector for sale. Optional measuring range 0~25% or 0~30%, output signal 4-20mA & RS485. The O2 gas detector can 24 hours online for oxygen concentration detecting, supports remote control, sound and light alarm, affordable price, reliable manufacturer.


    • Oxygen gas detector adopts high precision sensor for accurate gas leak detection.
    • Oxygen gas detector is equipped with 3-wire system 4-20mA analog output, relay output, RS485 output (optional).
    • The O2 gas detector is compatible with various controlled alarms, PLC, DCS and other control system, and can be remote monitored.
    • Explosion-proof design, fast, relaible and stable.
    • Infrared ray controller can remote control the alarm point settings, zero calibration, and address modification.
    • Two-stage alarm with sound and light, and the alarm point is settable.
    • The oxygen gas detector has self-calibration function, and three standard keys will be used to realize on-site maintenance.
    • The O2 gas detector can output one or two on-off signals, can drive ventilator, solenoid valve or other external devices.


    Model GD300-O2
    Detection Principle Electrochemistry
    Gas Oxygen (O2)
    Range (Optional) 0~30% Vol, 0~25% Vol
    Resolution 0.01%Vol
    Accuracy ≤±3% F.S.
    Responce Time ≤10s
    Repeatability ≤±1%
    Recovery Time ≤10s
    Linearity Error ≤±1%
    Zero Shift ≤±1% (F.S./year)
    Signal Output (Optional) Note 4-20mA and RS485
    Relay output: one group of relay output (1NO+1NC, 24V 100mA) for one alarm (default), or two groups of relay output (2NO+2NC, 24V 100mA) for high/low alarm (optional).
    Alarms Sound, light
    Display High light nixie tube display
    Installation Wall-mounted, piping type, flow-type (according to the detected environment)
    Connection G1/2 is the inlet and outlet for power and signal lines
    Pipe-mounted type: The installation thread size of the instrument is M45*P2.0
    Operating Time 24h
    Explosion-proof Grade Ex d llC T6
    Protection Grade IP65
    Certification CE, ATEX
    Working Voltage 12~36V DC
    Case Material Die-casting aluminum housing
    Operating Temperature -20℃~50℃
    Operating Humidity 0~95%RH (non-condensing)
    Dimension 206*179*90mm
    Weight ≤1.6kg
    Accessories Power adapter: Input 100-240VAC 50/60Hz, Output 24VDC 2A (Optional USA plug & Europe plug)

    Note: To measure confined spaces such as pipelines, please contact us and inform the detailed conditions of use.

    Fixed Oxygen (O2) Gas Detector Dimension (Unit: mm)

    Fixed gas detector with alarm dimension

    ***Other Common Gases and Ranges Available for Fixed Gas Detectors

    Gas Type Measure Range Resolution
    Ammonia (NH3) 0-50/100/200/500/1000ppm 0.01ppm/0.1ppm/1ppm
    Benzene (C6H6) 0-1/10/50/100/200/1000/2000/5000/10000ppm 0.001ppm/0.01ppm/0.1ppm/1ppm
    Carbon Dioxide (CO2) 0-1000/2000/5000/9999ppm, 0-1/5/100%VOL 0.1ppm/1ppm/0.001%VOL
    Carbon Monoxide (CO) 0-10/20/50/100/500/1000/2000ppm 0.01ppm/0.1ppm/1ppm
    Chlorine (Cl2) 0-10/20/50/100ppm 0.01ppm/0.1ppm
    Chlorine Dioxide (ClO2) 0-1/5/10/20/50/100ppm 0.001ppm/0.01ppm/0.1ppm
    Ethylene (C2H4) 0-50/100/500/1000/2000ppm 0.01ppm/0.1ppm/1ppm
    Formaldehyde (CH2O) 0-10/20/50/100ppm 0.01ppm/0.1ppm/1ppm
    Hydrocarbons (HC) 0-100%LEL 1%LEL
    Hydrogen (H2) 0-1000/2000/5000/9999ppm, 0-1/4%VOL 1ppm/0.001%VOL
    Hydrogen Chloride (HCL) 0-10/20/50/100/200ppm 0.01ppm/0.1ppm
    Hydrogen Cyanide (HCN) 0-10/20/50/100ppm 0.01ppm/0.1ppm
    Hydrogen Sulfide (H2S) 0-20/50/100/200ppm 0.01ppm/0.1ppm
    Methane (CH4) 0-50/100%VOL, 0-100%LEL 0.01/0.1%VOL/1%LEL
    Nitric Oxide (NO) 0-20/50/100/250/500/1000ppm 0.01ppm/0.1ppm/1ppm
    Nitrogen (N2) 0-100%VOL 0.01%VOL
    Nitrogen Dioxide (NO2) 0-20/50/100/500/1000ppm 0.01ppm/0.1ppm/1ppm
    Nitrogen Oxides (NOX) 0-1/5/10/20/50/100/250/500/1000ppm 0.001ppm/0.01ppm/0.1ppm/1ppm
    Oxygen (O2) 0-25/30%VOL 0.01%VOL
    Ozone (O3) 0-1/5/10/20/50/100ppm 0.001ppm/0.01ppm/0.1ppm
    Phosphine (PH3) 0-10/20/50/100/500/1000/2000/3000ppm 0.01ppm/0.1ppm/1ppm
    Sulfur Dioxide (SO2) 0-20/50/100/500/1000ppm 0.01ppm/0.1ppm/1ppm
    Volatile Organic Compounds (VOC) 0-1/5/10/20/50/100/200/500/1000/2000/5000/10000ppm 0.001ppm/0.01ppm/0.1ppm/1ppm
    Combustible Gas (EX) 0-100%LEL 1%LEL

    Note: Some common gases and the measuring ranges are listed in the above table. For more information, please feel free to contact us.


    Fixed Oxygen (02) Gas Detector Details

    Tips: Why you need an oxygen gas detector?

    Oxygen detection is very important for entering confined spaces and entering certain open spaces below the ground. Other gases with higher density than air (such as gasoline, hydrogen sulfide, etc.) will accumulate in the downward direction, thereby displacing O2 in the space. There are two concentration points to consider in the detection of oxygen concentration: one is that too low O2 concentration will cause suffocation, and the other is that excessive oxygen exceeding the constant may cause unimaginable acceleration and enhancement of combustion or other chemical reactions. The concentration of oxygen in normal air is about 20.9%, and the balance (over 78%) is mainly nitrogen, and the rest includes a small amount of water vapor, carbon monoxide and other gases.

    Most confined space standards and law enforcement agencies, such as OSHA, use the volumetric concentration of O2 to determine whether it is insufficient, and the usual lower limit is 19.5%. This is also the lowest alarm point set by most manufacturers on the oxygen gas detector. Some law enforcement agencies also use partial pressure of gas instead of concentration to indicate insufficient oxygen. In this case, if the O2 partial pressure is lower than 16.3 kPa or 122 mHg, it is deemed insufficient (16 kPa oxygen partial pressure is approximately equivalent to 16.3% oxygen concentration at sea level). The reason for using partial pressure is that the human body relies more on oxygen partial pressure rather than concentration for breathing.

    Gas Detector 3-Wire System

    In the realm of gas detection systems, the 3-wire configuration offers a robust wiring solution, especially for applications requiring analog output. This video will show you the 3-wire gas detector wiring.

    Gas Detector 4-Wire System

    The wiring of the 4-wire gas detector supports the RS485 interface Modbus RTU communication mode. This video will show you the 4-wire gas detector wiring.

    Using Cloud Data and 4G for Fixed Gas Detectors

    This video will show you about the applications of cloud data and 4G transmission for fixed gas detectors.

    Monitoring Combustible Gas in Pipelines

    This video will show you how to monitoring combustible gas in pipelines.

    Existing reviews of Fixed Oxygen (O2) Gas Detector, 0 to 25% / 30% Vol
    Good performance
    I recently acquired the Fixed Oxygen (O2) Gas Detector for our industrial facility, and I couldn't be more pleased with its performance. Its precision in monitoring oxygen levels within a broad measurement range, coupled with straightforward installation, has streamlined our safety protocols.
    From: Zephyr | Date: 16/10/2023
    Was this review helpful? Yes No (0/0)
    I have a question about your gas detector
    I am Watanabe from Japan and I'm a postgraduate student. I'm writing to you for the first time.
    I'm contacting you to enquire about <Gas-H2>.
    I'm interested in your product and I want to use it to measure H2 in the air. So I have questions about your product.
    Is this machine high precision? It's said that there is about 0.5‰H2 in the air, so I wonder whether this machine can measure by after the decimal point.
    From: Wong | Date: 28/09/2021
    Was this review helpful? Yes No (0/0)
    ATO Responded
    Yes, our gas detector can measure H2 in the air, and you can choose the measurement range 0-10 ppm (accuracy 0.001 ppm), or 0-500 ppm (accuracy 0.1 ppm).
    Can you help me find a suitable instrument for measuring formaldehyde gas?
    I want 7 of these units to be able to monitor from 0 to 100ppm of formaldehyde. We will use these inside a hatcher to monitor the levels as the chickens hatch out. I need to monitor for 3 days and I need the data to be able to be graphed out. Can you help me? Do you have a picture of the graph or does it just get exported to excel and then I have to do it myself?
    From: Bpayne | Date: 13/09/2021
    Was this review helpful? Yes No (0/0)
    ATO Responded
    1. The most common working time of our Portable Formaldehyde (CH2O) Gas Detector is 24 hours (after full charge). Therefore, if you want to exceed 72 hours working hours, then we recommend using fixed (CH2O) gas detectors, it can run continuously for a long time.
    2. Whether you will use our portable or fixed gas detector, you can only export the measurement data to the excel file without providing the historical graph.
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