Model OT-3

O2 in Natural Gas Analyzer​


The Model OT-3 is designed to run continuously for years with minimal maintenance and streamline the work of field technicians. This innovative instrument utilizes new sensor technology engineered with CO2 resistant electrolytes. In addition, the sensor has a built-in acid gas scrubber (patent pending).

The System

The OT-3 natural gas oxygen measurement system accurately monitors trace oxygen levels in a variety of gases at the ppm level. The transmitter is equipped with two user-selectable oxygen analysis ranges and is acceptable for operation in Class I, Division 2, Groups B, C and D hazardous environments when used in   conjunction with a non-incentive power source.

The system is housed in a weatherproof NEMA-4 case with a front door that swings open for easy access to the Micro-fuel Cell and transmitter controls. The OT-3 is designed to work with a variety of Flow Computers, such as TotalFlow or FlowBoss, and the system can be ordered in either AC or DC powered versions.

The Sensor

The heart of the system is Teledyne’s own A-2CNG Micro-fuel Cell oxygen sensor. This cell is a sealed electrochemical device which translates the amount of oxygen present in a sample into an electrical current. Unlike other sensors on the market, it comes complete with a built-in acid gas scrubber. By restructuring this sensor to accommodate the scrubber simplifies upkeep while minimizing the instrument size.

Additional Features

  • Two analysis ranges, user-selectable

  • Designed to work in tandem with the predominant FCUs in the industry

  • Operates at as low as 10 VDC

  • High sensitivity (0.5% FS)

  •  High accuracy (± 2% of FS at constant temperature

  • Insensitive to flow variation

  • Fast response and recovery

  • Long-life maintenance-free Micro-fuel Cell sensor

  • Unaffected by reducing agents (HCs, CO, SO2, etc.)

  • Easy to calibrate; no zero gas required

  • Rugged NEMA-4 bulkhead mount enclosure

  • Stainless steel sample system

  • H2S scrubber

  • Optional heater​


  • Ranges: Two user selectable ranges can be set between 0-10 ppm and 0-9999 ppm O2

  • Signal output: Voltage: 0–10 VDC, negative ground Current: 4-20 mA, negative ground

  • Range ID: 0-10 VDC

  • Alarms: Two user-settable non-latching alarms, with user adjustable programmable 0-20 min delay; one power failure relay (All are failsafe.)

  • Sample system: Pressure regulator to control inlet sample pressures 5-2000 PSIG

  • Coalescing filter, H2S Scrubber, Manual Span

  • Gas Valve Sensor: InstaTrace CO2: Trace Oxygen sensor for CO2 containing backgrounds

  • Accuracy: ± 2% of full scale at constant temperature; ± 5% of full scale through operating temperature range (at 100 ppm and higher user defined ranges) once temperature equilibrium is reached

  • ± 1 ppm for 10 ppm range under above conditions

  • Response time: 90% in less than 65 seconds at 68°F (25°C)

  • System power requirement: AC (100-240 VAC, 50/60Hz @ 2.8W), or DC (10-36 VDC @ 2.8W)

  • System enclosure: NEMA-4 enclosure. 15.85" x 11.8" x 8.1" (40 x 30 x 20.6 cm)​



​Two user-selectable ranges between 0-10 ppm and 0-9,999 ppm oxygen and a 0-25% (nominal) air calibration range
Range​ ID: 0-10 VDC

​Sensor Type

​A-2C or A-2C InstaTrace / B-2C or B-2C InstaTrace for low CO2 streams

​Signal Output

Voltage:      0-10 VDC, negative ground
Current:     4-20 mA, negative ground


​± 2% of FS at constant temperature
​± 5% of FS through operating temperature range (at 100 ppm and higher) once temperature equilibrium is reached​
± 1 ppm for 10 ppm range under above conditions


0.5% of FS


​Light emitting diode (LED) display


​32° to 122°F (0° to 50°C)

​Response Time

90% in less than 65 seconds at 77°F (25°C)


​AC:   100-240 VAC, 50/60 Hz at 2.8 W)
DC:   10-36 VDC at 2.8 W


​Two user-selectable non-latching alarms, with user adjustable programmable 0-20 min delay
One power failure relay (all are failsafe)


​NEMA-4 enclosure; suitable for use in Class 1, Div 2 as long as they relay ratings are followed:
DC Rating:    0-30 VDC maximum at 0.9 amps maximum
AC Rating:    125 VAC maximum at 0.2 amps maximum;
                       Minimum reliable switching rating: 10 +  ​A at 10 mV


​15.8"H x 11.8"W x 8.1"D (40 x 30 x 20.6 cm)
30.9 lbs​ (14 kg)



​File Size​

Model OT-3 Brochure​


Model OT-3 M​anual​