Series 3500 Trace Oxygen Transmitter

Series 3500 Percent Oxygen Transmitter with a single range of 0-500, 0-1,000, or 0-10,000 ppm available online. Looped powered at 14-32 VDC.

Series 3500 includes the following:

  1. Accurate and dependable trace oxygen measurements in a variety of background gases
  2. Long-life Ambient Temperature Electrochemical Sensor
  3. NEMA 4 Enclosure
  4. 4-10 mADC output
  5. Factory calibration, NIST calibration certificates available upon request

For a full list of product Specifications and Resources click here.

Standard Lead Time: Due to increased demand, current lead time is 5 weeks.

*Select a model from the drop down list to see included features.

Other Configurations Available: Request a Quote

SKU: 3500 Category:


The Series 3500 Trace Oxygen Transmitter is a true loop powered (14-32 VDC) trace oxygen transmitter 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 enclosure is made from durable polycarbonate, and is rated for NEMA 4 (IP 66) service (may change with the addition of certain optional equipment).  A 4-20 mADC output is provided that can be used with a data logger, recorder, PLC, DCS, etc.

The Series 3500 Trace Oxygen Transmitter features  Alpha Omega Instrument’s long-life ambient temperature electrochemical sensor that has a functional life of up to three times that of most “fuel cell” type sensors.

The enhanced mechanical design of the sensor ensures longer life, and virtually eliminates leakage of caustic electrolyte, a nagging (and expensive) problem associated with sensors that require periodic electrolyte maintenance. And, because the sensor is sealed, it is not position sensitive. In addition, unlike some electrochemical sensors, Alpha Omega Instruments readings from the Series 3500 do not require manual adjustment based on changes in the molecular weights of the sample gas i.e. helium, hydrogen, etc. a major advantage for continuous measuring applications. The output from the sensor is both linear and temperature compensated to provide optimum performance.


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.

Economically priced

Affords savings of up to 30% and more over other manufacturers trace oxygen transmitters.

Wide Measurement Ranges

Measure from under 1 PPM to as high as 20,000 PPM oxygen.

Factory Calibration

Factory calibration included at no additional charge. Upon request, NIST calibration certificates available

NEMA 4 Enclosure

Greater installation flexibility with a dust and waterproof enclosure.


  • 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. ¹Stated at constant temperature and pressure
  • 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) <40° F (<5° C) use heated sensor enclosure >104° F (>40° C) cooling of sample gas/sensor required
  • Warranty: Two years electronics one year sensor.


  • 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


  • 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.


Additional information

Weight 6 lbs
Dimensions 20 × 15 × 9 in


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