Within the air, a normal concentration of oxygen is 21%, while nitrogen makes up 78% of the rest of the atmosphere along with some trace gases. Inert gases such as nitrogen, argon and helium although aren’t toxic, they do not help to support human breathing. These are odourless, colourless and tasteless making them undetectable. An increase in the volume of any other gases that are not oxygen can lead to a circumstance in which individuals may be at risk of asphyxiation which can cause serious injury or even death. This removal of oxygen gas in the air we breathe makes having an oxygen depletion sensor not just useful, but essential to maintaining life.

How is Nitrogen used to control oxygen levels?

Nitrogen (N2) can be used to control levels of oxygen in a laboratory. When carrying out tasks within the pharmaceutical industry, when transferring products or packaging process, nitrogen is used. Nitrogen is used to take oxygen away from the packaging prior to it being sealed, to make certain the product is preserved. As a result of this the need for an oxygen deficiency monitor is very important. Fixed or portable devices have the ability to detect oxygen levels within a laboratory, plant or utility room. Fixed gas detection systems are suitable for monitoring an area or room, whereas a portable gas detector is designed to be worn on the person within your breathing area.

What are the Risks of Oxygen depletion?

There are three main reasons why monitors are needed; it is essential to detect oxygen deficiencies or enrichment as too little oxygen can prevent the human body from functioning leading to the worker losing consciousness. Unless the oxygen level can be restored to a normal level the worker is at risk of potential death. An atmosphere is deficient when the concentration of O2 is less than 19.5%. Consequently, an environment that has too much oxygen in it is equally dangerous as this constitutes a greatly increased risk of fire and explosion, this is considered when the concentration level of O2 is over 23.5%.

In the absence of adequate ventilation, the level of oxygen can be reduced surprisingly quickly by breathing and combustion processes. Oxygen levels may also be depleted due to dilution by other gases such as carbon dioxide (also a toxic gas), nitrogen or helium, and chemical absorption by corrosion processes and similar reactions. Oxygen sensors should be used in environments where any of these potential risks exist. When locating oxygen sensors, consideration needs to be given to the density of the diluting gas and the “breathing” zone (nose level). For example, helium is lighter than air and will displace the oxygen from the ceiling downwards whereas carbon dioxide, being heavier than air, will predominately displace the oxygen below the breathing zone. Ventilation patterns must also be considered when locating sensors.

Oxygen monitors usually provide a first-level alarm when the oxygen concentration has dropped to 19% volume. Most people will begin to behave abnormally when the level reaches 17%, and hence a second alarm is usually set at this threshold. Exposure to atmospheres containing between 10% and 13% oxygen can bring about unconsciousness very rapidly; death comes very quickly if the oxygen level drops below 6% volume. Oxygen sensors are often installed in laboratories where inert gases (e.g., nitrogen) are stored in enclosed areas.

How do Fixed or Portable Devices Detect Oxygen?

Crowcon offer a range of portable monitors; Gas-Pro portable multi gas detector offers detection of up to 5 gases in a compact and rugged solution. It has an easy-to-read top mount display making it easy to use and optimal for confined space gas detection. An optional internal pump, activated with the flow plate, takes the pain out of pre-entry testing and allows Gas-Pro to be worn either in pumped or diffusion modes.

T4 portable 4-in-1 gas detector provides effective protection against oxygen depletion. T4 multi gas detector now comes with improved detection of pentane, hexane and other long chain hydrocarbons. Offering you compliance, robustness and low cost of ownership in a simple to use solution. T4 contains a wide range of powerful features to make everyday use easier and safer.

Crowcon’s fixed detector XgardIQ is an intelligent and versatile fixed detector and transmitter compatible with Crowcon’s full range of sensor technologies. Available fitted with a variety of sensors for fixed flammable, toxic, oxygen or H2S gas detection. Providing analogue 4-20mA and RS-485 Modbus signals as standard, XgardIQ is optionally available with Alarm and Fault relays and HART communications. The 316 stainless steels are available with three M20 or 1/2“NPT cable entries. This device is also (SIL-2) Safety integrity level 2 certified fixed detector.