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Explosion Proof Oxygen Monitor, 0-25%, Incl 10+ Year Sensor
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Explosion Proof Oxygen Monitor, 0-25%, Incl 10+ Year Sensor

Available Product Options. Please choose from the menu below | In stock

$3,745.00 – $4,835.00

Product Summary

PureAire’s Explosion Proof Oxygen Deficiency Monitor is engineered for high-risk environments where inert gases such as nitrogen, helium, or argon are used. Designed with a rugged, explosion-proof enclosure, this monitor prevents ignition in areas with flammable dust, gases, or fibers—making it ideal for grain processing facilities, powder coating plants, oil and gas refineries, and similar hazardous locations.

Built to perform in extreme conditions, the monitor remains accurate in temperatures as low as -40°C. At its core is PureAire’s long-life zirconium oxide sensor, which delivers reliable, non-depleting performance for over 10 years in typical use—eliminating the need for frequent sensor replacement and reducing long-term maintenance costs.

Two-Year Extended Warranty Available for this product in the US, Canada, and Mexico
  • 99132 – Suitable for Class 1, Div 1 & 2, Groups B, C, D, Zones 1 & 2, Groups IIB+H2, IIA, IP66
  • 99133 – Suitable for Class 2, Div 1 & 2  Groups E, F, G, IP66
  • 99134 – NO Sample Draw Pump – Suitable for Class 1, Div 1 & 2, Groups B, C, D, Zones 1 & 2, Groups IIB+H2, IIA, IP66
  • 99136 – Suitable for Class 2, Div 1 & 2  Groups E, F, G/Includes RS-485 Serial Communication, IP66
  • Long-life 10+ year average sensor life
  • Two-alarm relay setpoints available or alarm defaults are set for 19.5% and 18.0%
  • No scheduled maintenance required
  • 3-year warranty
  • Digital display
  • 4-20mA analog output (Active)
  • No Drift due to thunderstorms or barometric pressure changes
  • Wall mounting brackets
  • Built-in flow sample pump up to 100ft (99132, 99133, 99136)
  • CE, UL, and C UL approval on enclosure

The Explosion Proof Oxygen Monitor offers long-lasting O2 deficiency detection. PureAire’s oxygen monitors are reliable, affordable, low maintenance, and provide continuous monitoring for an average of 10 years and more.

Ideal for use in electrically classified locations, confined spaces, analyzer shelters, petrochemical plants, cryogenic gas storage, and locations requiring remote sampling. The EX oxygen monitor can detect leaks of inert gases such as nitrogen, helium, and argon. The explosion-proof oxygen monitor can detect gas leaks at temperatures as low as -40°C.

The monitor features an easy-to-read local display, visual LEDs, and an audible alarm. The oxygen monitor can be linked to fire alarm systems for notification of all employees.

The operator interface is via a menu-driven magnetic keypad, allowing full access without opening the enclosure.

The optional RS-485 feature provides serial communication between a PLC or PC and the monitor, which enables the monitor to transmit current relay and fault status.

The zirconia sensor is not sensitive to temperature, humidity, or barometric pressure changes (including thunderstorms). Unlike other oxygen monitors, replacement sensors are not required, since we use a zirconium sensor, rather than a disposable electrochemical sensor lasting 1-2 years on average. “Supervised watchdog,” software runs 24/7 checking electronics and components. Any errors or inconsistencies are reported on the display.

By installing PureAire’s explosion-proof oxygen monitor, you can save as much as $400 annually and reduce the time-intensive cycle of replacing sensors.

 

Sampling Method Sample Draw
Range 0 – 25 %
Accuracy Delivers ±0.2% O2 accuracy (± 1% of full range)
Operating Temperature -40° to 140°F (-40° to +60ºC)
Display 3/4” backlit digital display
Sensor Type Long-life zirconium oxide sensor cell
Sensor Life 10+ years under normal conditions
Signal Outputs 4-20 mA Analog Output (Active)
Dual-Level Alarm Relay Contacts
Power Requirements 24 VDC
300 mA
Dimensions 99132/99134 – 6.69″(W) x 7.56″(L) x 9.45″(H)-169.92mm x 192.02mm x 240.03mm
99133/99136 – 6.69″(W) x 7.56″(L) x 9.45″(H)-169.92mm x 192.02mm x 254mm
Weight  16 lb
7.3 kg
Enclosure 99132/99134 – Explosion-proof Class 1, Div 1 & 2, Groups B,C, & D, Zones 1 & 2, Groups IIB+H2, IIA, IP66
99133/99136 – Explosion-proof Class 2, Div 1 & 2, Groups E, F, G99212Q – Explosion-proof Class 2, Div 1 & 2, Groups E, F, G, IP66
Calibration Calibration is not required. Periodic span adjustment as needed.
Country of Origin USA
Harmonized Tariff Code 8531.10.0045

 

Additional O2 Monitor Accessories List Price
8 Channel Controller US (P/N # 99196)
Horn and Strobe  US (P/N # 42012,42013,42014
Remote Display US (P/N # 99091)

Connects to DCS and PLC Controls

PureAire’s Explosion-Proof Oxygen Monitor continually checks oxygen concentration levels and relays information to the distributive control system, PureAire’s single or multichannel controllers, or a programmable logic controller. It can be operated remotely over a 0.6-mile or 1,000-meter radius.

Improved Oxygen Sensor Cell

Rather than the electrochemical sensor used by most companies, PureAire uses a current-limiting zirconium oxide sensor. This sensor runs reliably without a reference gas, so it can be used in all-nitrogen environments. The Earth provides calibrated oxygen. When everything is at an ambient state, the sensor is challenged by approximately 20.9% oxygen. PureAire’s Explosion-Proof Oxygen Monitor checks oxygen levels from 0 to 25% and can operate at lower temperatures than the competition.

One-Step Sensor Adjustment

PureAire Oxygen Deficiency Monitors require occasional testing with nitrogen to validate the sensor’s response to low oxygen levels. While calibration is not necessary for our monitors to accurately measure oxygen depletion levels1, annual fine-tuning might be needed to ensure the sensor’s span accurately corresponds to the standard 20.9% oxygen concentrations.

PureAire’s Auto-Span not only simplifies the process of adjusting the span of the oxygen sensor but also provides a quick check of the sensor and the monitor’s response to an oxygen-deficient atmosphere. With the press of a button, this feature saves you time and money, protects your facilities and employees, and, most importantly, provides you with the reassurance of consistently reliable performance, making it a valuable addition to your safety measures.

1Please follow your facility’s safety guidelines and state and local regulations regarding calibration requirements for safety equipment.

Features of the Explosion-Proof Oxygen Monitor 

PureAire’s Explosion-Proof Oxygen Monitor comes in several configurations. All units have a built-in CPU and a low-cost, basic display-only monitor. For additional capabilities, a full-featured dual-level monitor is available. The unit features built-in alarm relays and an air check program that monitors sample flow, sensor cell, and electronics. For full transparency, fault information is transmitted to the alarm relay, front panel LED, and mA output.

Explosion-Proof Oxygen Monitor Literature

O2 Sample Draw Monitor Manual – Rev 5.06 

Safety Risks of Oxygen Deficiency 

NIH – Protocol for Use & Maintenance of Oxygen Monitoring Devices 2021

O2 EX Monitor Relays and Remote

O2 Flame Arrestor Class II

Comparison O2 Zirconium Oxide vs EC cell

Comparison of 10-Year Sensor vs. Electrochemical

O2 Test Against other Companies

Oxygen Monitor Sales Presentation

Remote Digital Display p/n 99091

Flameproof / Hazardous Location Strobe with Optional Horn

CloudConnect

 

8-Channel Touch Screen Programmable Controller

Domestic 24VDC Power Supply 45101

 

International 220V Power Supply 45102

 

Replacement Filter 90115

 

Explosion-Proof Design

Built for hazardous or classified environments.

O₂ Deficiency Safety

Helps identify oxygen displacement risk in inert-gas operations.

Continuous Monitoring

Designed for around-the-clock oxygen status visibility.

Facility Readiness

Supports safety monitoring in industrial and process environments.

Oxygen deprivation is a silent killer. Oxygen-depleting gases, such as nitrogen, argon, and helium, are odorless and colorless, making leaks impossible to detect, unless appropriate monitoring is in place.

PureAire oxygen deficiency monitors can be used to monitor nitrogen, argon, and helium. Carbon dioxide can also be monitored with PureAire’s dual oxygen/carbon dioxide monitor.

PureAire uses a proprietary, non-depleting, zirconium oxide sensor that will last up to 10 years in a normal environment without needing to be replaced.

PureAire’s sensors do not operate under partial pressure, meaning that a PureAire sensor will not need to be adjusted to account for different elevations. Additionally, the sensors will not drift due to changes in barometric pressure.

In contrast, other gas detection companies use depleting, electrochemical sensors. These sensors, because they are depleting, operate for 1-2 years before needing to be replaced. Electrochemical sensors do not offer long-term solutions to companies committed to safety.

PureAire sensors are built to last 10 years. Often, the sensors work much longer. In fact, some of our first customers who started using PureAire products in 1997 report that the sensors are still in operation today.

On the other hand, an oxygen monitor that uses a depleting, electrochemical sensor is like a battery in that, as the sensor depletes, it begins to lose its power and responsiveness. In order to operate accurately, electrochemical sensors must be calibrated frequently.

PureAire sensors are made of non-depleting zirconium oxide, and calibration is typically not required.

However, a visual check of the monitor should be done once a year to verify that the sensor is functioning properly, and span adjustments should be done, as necessary. The sensor requires periodic testing with nitrogen to verify the sensor’s response to low oxygen levels.

In contrast, electrochemical sensors, because they deplete over time, will need to be calibrated every 2-3 months and totally replaced every 1-2 years.

Switching to a PureAire non-depleting, zirconium oxide sensor will save you time and money, while ensuring the safety of your workers and facility.

Electrochemical sensors offered by other gas detection companies lose accuracy over time and must be calibrated. Calibration recharges and resets the monitor to get an accurate reading. It is important to note that an electrochemical sensor can only be calibrated a finite number of times before it must be discarded.

PureAire’s non-depleting zirconium oxide sensor will not experience drift. Oxygen sensors from PureAire will provide long-lasting, reliable, and accurate monitoring for an average of10+ years.

The oxygen monitor covers an area of approximately 692 square feet when mounted on a wall and should be placed no more than 21 feet from potential leak sources such as gas lines, gas cylinders, or any areas where a gas leak might be expected to occur.

To ensure safety, the maximum distance between two monitors mounted to the same wall, should not exceed 30 feet. However, since cryogenic gases, such as argon, helium, and nitrogen, are unpredictable, we encourage you to contact PureAire for additional guidance specific to your needs.

In most circumstances, PureAire recommends that oxygen monitors be installed 3-5 feet away from gas cylinders or cryogenic gas lines. To enable employees to see the monitor display and verify its performance, PureAire recommends mounting an oxygen monitor 3-5 feet off the ground.

There are other options for mounting an oxygen monitor. For instance, PureAire sensors can sample the air from up to 100 feet away, or be installed within a glovebox, freezer, sealed chamber, or even underground. PureAire monitors can also work in environments that require KF-25 flanges, as well as in nitrogen/argon enriched environments.

PureAire’s Sample Draw Monitors pull a sample flow at a rate of 250 ccs per minute. We recommend using 1/4” OD x 3/16” ID polypropylene sample tubing. Using this internal tubing dimension, to calculate transport (response) time, add 2 seconds per foot of sample tubing. For example, if the sample tube is 10 feet long, the initial response time would be 20 seconds (10ft x 2seconds=20seconds) at 15 feet the response time would be 30 seconds (15ft x 2seconds=30seconds), etc.

The response time when using the entire 100 feet of sample tube will take 3.5 minutes (100ft x 2seconds=200seconds or 3.5minutes) for the sample to reach the monitor.