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Series 3500/3510 EX

Explosion Proof Trace Oxygen Transmitter

Unmatched Technology & Value

Explosion-Proof Oxygen Transmitter with Long-Life Sensor 

Our ALPHA OMEGA INSTRUMENTS™ Series 3500/3510 EX™ Explosion Proof Trace Oxygen Transmitters are explosion proof blind transmitters designed to provide exceptional performance, accuracy, and stability.  The Series 3500/3510 EX Trace Oxygen Transmitter is designed to provide accurate and dependable trace oxygen measurements in a variety of background gases.  Measurement ranges available are from 0-10 PPM to 0-20,000 PPM.

The Series 3500/3510 EX Explosion Proof Trace Oxygen Transmitters enclosure features an explosion proof enclosure rated NEMA 7 for use in areas requiring compliances to Class. I. Div. 1 & 2 Groups B, C, & D; Class II. Div. 1 & 2 Groups E, F & G; and Class. III protection. The enclosure is UL Classified, CAS Certified and FM Class No. 3615 approved. It includes flame arrestors, a conduit seal wye fitting with can of sealing compound and fiber.  A 4-20 mADC output is provided that can be used with a data logger, recorder, PLC, DCS, etc. Options include pressure regulators, flow meters, sample filters. The Series 3500 is the loop powered version, and the Series 3510 is the AC powered (115/230 VAC, 50-60 Hz) counterpart and is recommended when AC power is available or preferred. Also, available in optional 24 VDC.


A nemesis for many conventional “fuel cell” type trace oxygen sensors are their inability to measure oxygen in gases. Carbon dioxide reacts with potassium hydroxide electrolyte to form carbonic acid and in short time destroys the sensor. Not anymore. We offer an optional CO2 tolerant trace oxygen sensor with proprietary electrolyte. The CO2 tolerant sensor is capable of providing accurate oxygen readings in gases containing up to 100% CO2 without shortening the life of the sensor.


    Here are some of the industries that use the Series 3500/3510 Trace Oxygen Transmitters:

    • Semiconductor Manufacturing: Used in semiconductor manufacturing processes to monitor oxygen levels in process gases and to ensure the purity of the gases used in production.
    • Food and Beverage: Used in the food and beverage industry to monitor oxygen levels in packaging and storage environments to extend the shelf life of products and to prevent spoilage.
    • Pharmaceutical: Used in the pharmaceutical industry to monitor oxygen levels in production processes and to ensure the stability and efficacy of drug products.
    • Petrochemical: Used in the petrochemical industry to monitor oxygen levels in refining and processing operations to optimize process efficiency and to prevent corrosion.
    • Aerospace: Used in aerospace applications to measure oxygen levels in welding applications where excess oxygen promotes poor welds due to oxidation.
    • Research: Can be used in research applications with glovebox or anaerobic chambers, such as studying the effect of oxygen levels on plant growth, and in testing the oxygen content of experimental gas mixtures.
    • Industrial processes: Can be used in various industrial processes that require accurate measurement and control of oxygen levels, such as welding, metal processing and chemical processing.

    • Long Life Trace Oxygen Sensor: Provides up to three times the functional life of most “fuel cell” type sensors. Reliability is dramatically increased while maintenance costs are reduced.
    •  Sealed Sensor: Eliminates handling potassium hydroxide (caustic), a hazardous material or having to frequently “recharge” the electrolyte.
    •  CO2 Resistant Sensor: Optional CO2 resistant sensor is designed to operate with sample gases containing up to 100% CO2. Conventional “fuel cell” type sensors using potassium hydroxide (KOH) electrolyte can be poisoned from CO2.
    •  Affordable: Affords savings of up to 30% and more over other manufacturers trace oxygen transmitters.
    •  Wide Measurement Range: Measure from under 1 PPM to as high as 20,000 PPM oxygen.
    •  Factory Calibration: A factory Certificate of Performance Verification and Calibration is included at no additional charge. The product performance is verified in accordance with manufacturing specifications using a National Institute of Standards and Technology (NIST) traceable transfer calibrated standard gas mix.
    •  NEMA 4 Enclosure: Greater installation flexibility with a dust and waterproof enclosure (may change with the addition of certain optional equipment).

    • Measurement Ranges: (parts per million) 0-10, 0-50, 0-100, 0-500, 0-1,000, 0-5,000, 0-10,000, and 0-20,000
    • Accuracy¹: ±1% of full scale (± 5% of full scale on ranges ≤ 0-5 ppm)
    • Linearity: ±1% of full scale.
    • Response Time: 90% of full-scale response in less than 10 seconds (typical). The response time for ranges of 0-50 PPM or less depend to a great extent on the design of the sample delivery system including the materials used.
    • Sensor Type: Long-life Ambient Temperature Electrochemical Sensor (Optional CO2 Resistant Sensor Available).
    • Temperature Compensation: Standard.
    • Operating Temperature Range: 40° to 104°F (5° to 40°C)
    • Warranty: Two years electronics one year sensor.

    • Enclosure: Polycarbonate, rated NEMA 4X (IP66) without optional equipment
    • Dimensions: 5.5 in (139.9 mm) height. 8.8 in (223.5 mm) width. 3.4 in (86.4 mm) deep. Note: All dimensions are without optional equipment
    • Gas Connections: 1/4” stainless steel compression fittings

    • Series 3500 Loop Powered Trace Oxygen Transmitter: Input power 14-32 VDC
    • Analog Output: 4-20 mADC with a loop resistance of 600 ohms @ 24 VDC (consult factory for other resistance values)

    • Sample Flow Rate: 1.0 to 2.0 standard cubic feet per hour (SCFH). 0.5 to 1.0 liters/ minute (LPM).
    • Sample Gas Temperature: 40° to 104°F (5° to 40°C)
    • Sample Gas Pressure Limits: 0.1 to 1.5 psig (0.007 to 0.1 kg/cm2).
    • Entrained Solids: <3 mg/ft³: no in-line filter required >3 mg/ft³: in-line filter is required
    • Hydrocarbon Mist: <0.7 mg/ft³: no in-line filter required >0.7 mg/ft³: in-line filter is required

    We Care About Safety

    If you are concerned over unsafe levels of oxygen explore a complete line of oxygen deficiency monitors and accessories. We supply many instruments to medical, aerospace, and municipalities.  Occupational Safety and Health Administration (OSHA) defines an oxygen deficient environment when oxygen levels fall below 19.5 percent.  Oxygen deficient environments require accurate and reliable instrumentation. Oxygen levels below 16% is dangerous to human life.

    Explore why safety monitoring matters.

  • rohs-reach


Need service on your oxygen analyzer?  No problem.   We are ready to assist you with any technical or service-related inquiries.  Just complete our Oxygen Monitor RMA.


  • Improved reliability
  • Lower cost of ownership 
  • Improved product quality
  • Efficiency
  • Meet compliance requirements
  • Backed by global service and support

Process Insights is committed to solving our customers’ most complex analytical and process challenges.  


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Series 1000™

Series 1300 replaces the Series 1000
Series 1300 replaces the Series 1000

Series 1300™

ALPHA OMEGA INSTRUMENTS™ Oxygen Deficiency Monitor
Process Insights_Series 1300 Oxygen Monitor

ZRO 2000™

ALPHA OMEGA INSTRUMENTS™ Trace Zirconia Oxygen Analyzer PPM to 100%
Process Insights_AOI ZRO 2000 oxygen analyzer


ALPHA OMEGA INSTRUMENTS™ Percent Oxygen Analyzer 0-100% and 0-25%
Process Insights_AOI-OXY-SEN oxygen analyzer

Series 2000™

ALPHA OMEGA INSTRUMENTS™ Percent Oxygen Analyzer 0-1 to 0-100%
Process Insights_AOI_Series 2000 oxygen analyzer

Series 2500/2510™

ALPHA OMEGA INSTRUMENTS™ Percent Oxygen Transmitter 0-2% to 0-100%
Process Insights_AOI_ Series 2510-Percent-Oxygen-Transmitter

Series 2500/2510 EX™

ALPHA OMEGA INSTRUMENTS™ Percent Oxygen Transmitters Explosion Proof
Process Insights_AOI_ Series 2510-Percent-Oxygen-Transmitter

Series 2520™

ALPHA OMEGA INSTRUMENTS™ Portable Percent Oxygen Analyzer 0-5, 0-10, 0-25, 0-50, and 0-100%
rocess Insights_AOI_Series 2520 portable oxygen analyzer

Series 3000™

ALPHA OMEGA INSTRUMENTS™ Trace Oxygen Analyzer 0-1 PPM to 0-10,000 PPM
Process Insights_Series 3000 Oxygen Monitor

Series 3500/3510™

ALPHA OMEGA INSTRUMENTS™ Trace Oxygen Blind Transmitter 0-10 PPM to 0-20,000 PPM
Process Insights_Series 3500 Oxygen Monitor

Series 3500/3510™ EX

ALPHA OMEGA INSTRUMENTS™ Trace Oxygen Blind Transmitter Explosion Proof 0-10 PPM to 0-20,000 PPM
Process Insights_AOI_35003510 Explosion Proof Transmitter

Series 3520™

ALPHA OMEGA INSTRUMENTS™ Portable Battery-Operated Trace Oxygen Analyzer
Process Insights_Series 3520_oxygen monitor


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