An oxygen deficiency monitor continuously measures oxygen levels in an indoor space and alerts personnel when oxygen concentrations fall to potentially dangerous levels.
These monitors are especially important in facilities that use or store liquid nitrogen, liquid helium, argon and other cryogenic or inert gases that can displace oxygen if released.
Cryogenic gases are also widely used in laboratories, medical facilities, pharmaceutical operations, food processing, manufacturing, research facilities and other industrial applications. While many of these gases are not toxic, a leak or release can displace the oxygen in the surrounding air and create an oxygen-deficient atmosphere.
Because gases such as nitrogen, helium and argon are colorless and odorless, workers may have little or no warning that oxygen levels are falling. A properly installed oxygen deficiency monitor and alarm provides continuous O2 monitoring and can warn personnel before they enter an unsafe area.
What is an Oxygen Deficiency Monitor?
An oxygen deficiency monitor, sometimes called an O2 deficiency monitor, oxygen depletion monitor or low oxygen alarm, continuously measures the percentage of oxygen in the surrounding air.
Normal atmospheric air contains approximately 20.9% oxygen. OSHA defines an oxygen-deficient atmosphere as one containing less than 19.5% oxygen by volume.
When oxygen concentrations fall below a configured alarm threshold, an oxygen deficiency monitoring system can provide audible and visual warnings to alert employees and prevent entry into a potentially hazardous area.
Depending on the system and facility design, fixed oxygen monitors may also integrate with:
- Remote displays
- Horns/Strobes (Visual Alarms)
- Ventilation or exhaust systems
- Building management systems
- Gas shutoff equipment
- Central monitoring systems
- Power monitoring units
These capabilities make fixed oxygen monitoring especially useful in areas where cryogenic gases are routinely stored, transferred or used.
Why Cryogenic Gases Can Cause Oxygen Deficiency
Cryogenic liquids are gases that have been cooled to extremely low temperatures so they can be stored and transported in liquid form.
Common cryogenic liquids include:
- Liquid nitrogen (LN2)
- Liquid helium
- Liquid argon
- Liquid oxygen
- Liquid carbon dioxide
- Other industrial cryogenic gases
When many cryogenic liquids warm and vaporize, they expand dramatically. If a significant release occurs inside a room or enclosed area, the expanding gas can displace normal atmospheric air.
This is especially dangerous with gases such as nitrogen, helium and argon, which can act as simple asphyxiants. These gases may not be toxic themselves, but they can reduce the concentration of oxygen available for breathing.
That is why oxygen monitoring is an important component of cryogenic gas safety.
What Oxygen Level Is Considered Dangerous?
Normal atmospheric oxygen is approximately20.9% by volume.
OSHA defines an oxygen-deficient atmosphere as less than 19.5% oxygen by volume. Facilities using compressed or cryogenic gases should evaluate whether a gas release could reduce oxygen below safe levels and implement appropriate engineering controls, ventilation, monitoring and emergency procedures.
As oxygen levels continue to fall, the potential for impaired physical and cognitive performance and other serious health effects increases.
An oxygen deficiency alarm provides an early warning when oxygen levels move outside configured safety limits, allowing personnel to follow their facility's emergency procedures rather than unknowingly entering an unsafe environment.
Alarm setpoints, system design and response procedures should always be based on applicable regulations, codes, manufacturer instructions and a facility-specific hazard assessment.
Cryogenic Applications for Oxygen Deficiency Monitors
Oxygen deficiency monitoring is used across many industries where cryogenic or inert gases are stored or used.
Below we highlight and list the most common applications.
1. Laboratories and Research Facilities
Laboratories commonly use liquid nitrogen, helium and other gases for sample preservation, analytical equipment, research and cooling applications. A release inside a laboratory, storage room or enclosed space can create an oxygen-deficiency hazard.
2. Medical and Healthcare Facilities
Cryogenic gases are used in medical research, MRI and NMR applications, fertility and reproductive medicine, tissue storage and other healthcare applications.
Facilities that store large quantities of liquid nitrogen or other cryogenic gases should evaluate ventilation and oxygen monitoring requirements for areas where a release could displace oxygen.
3. Cryotherapy and Cryosurgery
Cryogenic gases may also be used in specialized medical and therapeutic applications. Because these systems can involve extremely cold gases or liquids, facilities must consider both the physical hazards associated with cryogenic temperatures and the atmospheric hazards associated with gas releases.
4. Food Processing and Cryogenic Freezing
Liquid nitrogen and carbon dioxide are used in some food-processing and rapid-freezing applications. Rapid cryogenic freezing can help reduce changes to food products during the freezing process.
The quantity of gas, room volume, ventilation and type of gas being used should all be considered when determining the appropriate gas detection strategy.
5. Pharmaceutical and Biotechnology Facilities
Pharmaceutical, biotechnology and life-science facilities frequently rely on cryogenic storage for samples, biological materials and temperature-sensitive products. Continuous oxygen monitoring can provide another layer of protection in rooms containing cryogenic freezers, dewars or bulk gas systems.
Where Are Oxygen Deficiency Monitors Required or Recommended?
An oxygen deficiency monitor combines an oxygen sensor with a remote monitor and staff can be warned before they enter an area that has depleted oxygen levels.
They can also monitor areas remotely. The oxygen deficiency monitor and alarm can be connected to the facility’s HVAC system, or can notify emergency first responders of a gas leak.
By providing unique, high quality, detection devices, analyzers, and sensors; CO2Meter strives in each customer interaction to provide education about gas detection and monitoring, and to ensure the health, welfare, and safety of the public. Contact our team of experts today.
Frequently Asked Questions about Oxygen Deficiency Monitors
What is an oxygen deficiency monitor?
An oxygen deficiency monitor is a gas safety device that continuously measures the concentration of oxygen in an area. It can activate audible and visual alarms when oxygen reaches configured low or high alarm thresholds.
What oxygen level is considered oxygen deficient?
OSHA defines an oxygen-deficient atmosphere as an atmosphere containing less than 19.5% oxygen by volume.
Why do I need an oxygen monitor around liquid nitrogen?
Liquid nitrogen rapidly expands into nitrogen gas as it warms. In an enclosed or inadequately ventilated space, released nitrogen can displace oxygen and create an oxygen-deficient atmosphere. Continuous oxygen monitoring can warn personnel when O2 concentrations fall to unsafe levels.
Can you smell an oxygen deficiency?
No. Oxygen deficiency itself has no smell. Inert gases commonly associated with oxygen displacement, including nitrogen, helium and argon, are also colorless and odorless. Workers should not rely on their senses to identify an oxygen-deficient atmosphere.
Where should an oxygen deficiency monitor be installed?
Monitor and sensor placement depends on the gas being used, potential leak sources, room configuration, ventilation and manufacturer requirements. A facility-specific risk assessment should be performed to determine the appropriate number and placement of sensors, displays and alarms.
Do laboratories need oxygen deficiency monitors?
Laboratories that use or store compressed gases or cryogenic liquids should evaluate their potential for oxygen displacement. Monitoring requirements can depend on gas quantities, ventilation, room size, applicable codes and the facility's risk assessment.
Do I need an oxygen monitor for liquid nitrogen?
Facilities using or storing liquid nitrogen should evaluate the potential for nitrogen releases to displace oxygen. In enclosed rooms, cryogenic freezer areas, laboratories and similar spaces, fixed oxygen monitoring may be required or recommended depending on the application, gas quantity, ventilation and applicable requirements.
Is a portable oxygen monitor enough for cryogenic safety?
Portable monitors can provide personal protection, but they do not continuously monitor a room when personnel are outside it. A fixed oxygen deficiency monitoring system can detect hazardous conditions before someone enters the affected area and can provide remote audible and visual alarms.
Does an oxygen deficiency monitor detect nitrogen leaks?
An oxygen deficiency monitor generally does not measure nitrogen directly. Instead, it detects the decrease in oxygen concentration caused when nitrogen or another inert gas displaces normal air.
Is an oxygen monitor the same as a CO2 monitor?
No. An oxygen monitor measures oxygen concentration, while a CO2 monitor directly measures carbon dioxide. The correct monitor depends on the gas hazard. Facilities using CO2 or dry ice may require direct CO2 detection rather than relying solely on an oxygen deficiency monitor.
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