Model 3350​​​

Control Room Oxygen Monitor​​​​​​​


​The Model 3350 accurately measures the concentration of oxygen in control rooms, closed atmospheres, critical breathing circuits and other applications that require the fail-safe monitoring of breathable, ambient air. It is a microprocessor-based oxygen alarm monitor for real-time measurement of the oxygen content of the atmosphere surrounding the sensor as well as shoulders the burden of personal safety with the quality and reliability offered by the Teledyne name.


Dual Oxygen Analyzers 

The alarm set-points provide an operational band that covers all acceptable oxygen concentrations. If the oxygen level at the sensor crosses the adjusted set-point of one of the alarms, that alarm will cause the switching of relay contacts. The standard factory setting of the two alarms provides a CAUTION alarm at 20% oxygen and a DANGER alarm at 19.5% oxygen. To cover special situations, a limited amount of adjustment is possible. Both alarm set-points are factory set (internal) to prevent tampering or resetting by    unauthorized personnel. When insufficient oxygen concentration triggers either alarm, a red panel light and an audible annunciator are energized. The alarms remain energized until the oxygen concentration has been elevated above the trigger point.

Battery Backed Standby Power

An optional battery backed standby power configuration is offered for potential power failure or “brown out” conditions. With this feature, power outages will not interfere with a proper working alarm. The standby power source uses a rechargeable lead acid battery. If the AC power is interrupted, the stand-by power supply automatically supports analyzer operation. Periodic testing of the battery pack is possible through a simple pushbutton inside the instrument’s control panel.

Easy to Install

The unit is designed for easy installation. Mount the unit to a wall or bulkhead, connect AC power and the installation is complete. The unit is lightweight with a slim profile, eliminating the need for special reinforcement in most installations.

Maintenance Free Sensor

The 3350 uses a patented Micro-fuel Cell to measure the concentration of oxygen in breathable air. This sensor is a sealed electrochemical transducer with no electrolyte to change or electrodes to clean, so it is virtually maintenance free. When it reaches the end of its useful life, it is easily replaced.

Simple Calibration

Periodic calibration is quickly and easily accomplished with no specialty gas requirements. The Micro-fuel Cell produces a linear output from 0 to 100% oxygen so ambient air or readily available instrument grade air (20.9% oxygen) can be economical used for calibration. Also, since the Micro-fuel Cell has an absolute zero, no zero gases are needed.

Remote Probe

A special version of the unit is available with a remote-mountable oxygen probe. This option permits the user to install the oxygen probe inside the control room, while the control unit is mounted outside. This allows personnel to see the analyzer and confirm a safe level of ambient oxygen is present before entering the control room.​


  • ​Battery back-up

  • Power requirement: 100 / 220 VAC, 50 / 60 Hz

  • Special Ranges

  • Special Remote Probe

  • Provisions for conduit in power connection​


  • ​Large, bright, LED meter readout

  • Nylon cell holder

  • Audible and visual alarm indicators

  • Simple pushbutton controls

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

  • Unaffected by oxidizing gases

  • Fast response and recovery time

  • Microprocessor based electronics

  • CE Mark approval

  • Air calibration range for convenient spanning at 20.9% oxygen

  • Two factory present alarms, Form C relay contacts, configured as failsafe and non-failsafe

  • Two analog outputs: two for measurement (0-10 VDC and negative ground 4-20 mA)

  • Compact and rugged, wall mounted NEMA-4 rated enclosure​​



​0-25% oxygen


​0-5% of FS


​± 2% of FS at contant temperature
± 5% of FS (over operating temperature range, once the system has reached equilibrium at a contstant temperature)

Response Time

​90% in less than 20 seconds at 77°F (25°C)


​32° to 122°F (0° to 50°C)

​Relative Humidity

0-95% non-condensing

​Maximum Altitude

​6,562 feet (2,000 meters)


​± 1% of FS

​Sensor Type

​B-3 class Micro0fuel Cell

​Battery Life

48 hours (non-alarm conditions) non-failsafe
17 hours (non-alarm conditions) failsafe


​AV 100 to 240 VAC at 50/60 Hz, 0.3A Max
Battery back up version charges and maintains at 12 VDC lead acid battery

​Signal Output

​Voltage:      0-10 VDC, negative ground (10 mA max)
Current:     4-20 mA, negative ground (15V max open circuit) 10 VDC / 500 ohms maximum
                    operating range


12-15 VDC, 4.3 mA max
Factory set:           Caution - 20%
                                Danger - 19.5%
Sensor Failure:     Audible - buzzer
                                Visual - red indicator lamps


​Wall mounting, NEMA-4 enclosure


​8"W x 10"H x 6"D
(20.3 x 25.4 x 15.2 cm)



​​File S​ize​​​​

Model 3350 Brochure​


Model 3​350 Instruction Manual