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FAQ about oxygen reduction

Everything you need to know about fire prevention through oxygen reduction

According to statistics, a fire breaks out every two minutes in Germany and often causes considerable damage. Whether warehouses, data centers or archives - all businesses depend on absolutely reliable fire protection. No company can afford downtime. That's why, in the event of a fire - in addition to personal protection - maintaining operational processes has top priority.

Traditional fire protection systems are passive, i.e. they only react once a fire has already broken out. Our preventive oxygen reduction system OxyReduct®, on the other hand, starts before a fire starts and thus actively ensures maximum safety. Consequential damage, as occurs after extinguishing with water or other extinguishing agents such as foam, is avoided. Through a controlled supply of nitrogen to a protected area, the oxygen level is continuously maintained at a lowered level below the ignition limit of a fire. The result: the risk of an open fire is greatly reduced.

We have summarized the most important and frequently asked questions on the subject of fire prevention through oxygen reduction for you here:

Oxygen reduction is a fire prevention technology designed to help fully achieve individual protection goals in specific application scenarios. Depending on the materials stored or installed or the equipment to be protected, the oxygen concentration of the ambient air in the protected area is reduced to a defined level.

Conventional fire protection systems (extinguishing systems) are passive, i.e. they only react once a fire has already started. An oxygen reduction system is active (preventive) and kicks in before a fire starts. It creates an atmosphere in enclosed spaces in which there is no risk of a full-scale fire starting and spreading under defined conditions.

For a fire to start, three components must be present: oxygen, thermal energy and fuel. If one of these components is removed, a fire has no chance of developing and spreading further. Fire prevention technology is based on this principle: By reducing the amount of oxygen, the fire is literally "deprived of the air it needs to breathe".

For almost all fuels, their flammability is directly related to the oxygen concentration in the ambient air and decreases accordingly as the concentration decreases. Below a limit value of the oxygen concentration in the ambient air, independent burning of the substances is no longer possible. This value, known as the ignition limit, is substance-specific. For cardboard/board packaging, for example, the specific ignition limit is 15.0% by volume. The normal oxygen content in air is 20.95% by volume.

Specific ignition limits are determined in a standardized VdS test procedure (VdS Guideline 3527). The oxygen concentration, which is important for the design of a plant, must be reduced by a necessary safety margin, e.g. for cartonboard/cardboard packaging the design concentration is 14.0 vol.-% (according to VdS guideline 3527), which corresponds to an operating concentration of 13.7 vol.-%.

The use of this technology is directly related to the fire risks in the area to be protected and the defined protection goals. In today's market, protection goals that go beyond the legal guidelines, i.e. the protection of people and the environment, as well as insurance requirements, are increasingly common. Certain protection goals derived from individual risk awareness, such as protection of irretrievable values or high value concentrations, protection of goods availability, delivery capability as well as operational capability, can only be achieved with the help of oxygen reduction. Typical applications for this are:

  • Cold storage
  • Automated high-bay warehouses
  • Automated compact container storage
  • Hazardous materials storage
  • Museums, art collections and archives
  • Storage of lithium-ion batteries

The healthy person can live and work for a certain period of time with less oxygen without restriction. The stay in an oxygen-reduced atmosphere is comparable to a stay at altitude: Humans are used to getting by with less oxygen than is present in the air they breathe (20.9%). The decreasing partial pressure of the air with increasing geodetic altitude leads to a reduced intake of oxygen of each breath, such as on mountains or in airplanes.

Nitrogen generation is a physical process by which air is broken down into its components on site. There are various methods by which nitrogen can be generated from ambient air. The most common methods are the use of membrane technology or activated carbon.

Membrane technology: In the principle of membrane technology, the ambient air is forced under pressure through a bundle of polymer fibers. The separation of oxygen and nitrogen molecules takes place in these fibers. The oxygen molecules diffuse through the fiber walls, while the larger nitrogen molecules flow through the fiber. The extracted nitrogen is introduced into the protected area via a network of pipes. Due to this type of separation of oxygen and nitrogen molecules, a continuous volume flow prevails in membrane technology.

Activated carbon: In the activated carbon principle, the oxygen and nitrogen molecules in the ambient air are separated from each other by means of carbon molecular sieves (CMS). Air is forced through the CMS bed (filter) at a slight overpressure in two identical vessels. This process is also known as Vacuum Pressure Swing Adsorption (VPSA) or Pressure Swing Adsorption (PSA).

Conventional nitrogen generators need energy. Since the development of the first oxygen reduction plants began, the market-leading companies have reduced the energy requirements of these systems by 80 %. This trend will continue all the way to CO2 neutrality. Fire protection is environmental protection - this also applies to resource requirements.

In the planning phase, the question of the better solution must first be answered, i.e., which solution will achieve my individual protection goals while taking into account the specific risks. If this consideration shows that two different types of plant fire protection are in fact equally possible (e.g. sprinklers vs. oxygen reduction), the question of cost can be decisive. Experience shows that in the case of complex structural requirements and, for example, very dense and high high-bay warehouses, an oxygen reduction system offers significant cost advantages compared to a sprinkler system.

A maintenance contract (including service and emergency service) must be offered by the specialist installer and is also mandatory. Here, there is no higher effort compared to other safety-relevant fire protection systems.

The increasing degree of automation, increasingly dense storage forms, such as the compact container warehouse, increasing concentrations of value and protection goals that focus not only on the protection of persons and buildings, but also on protection against business interruptions and the preservation of delivery capability also indicate a trend in the insurance market. These risks and protection goals lead to an increasing relevance of oxygen reduction plants.

Oxygen reduction is not suitable for explosive substances. Detailed information on which substances are excluded or problematic can be found at the VdS in the project planning guideline VdS 3527 as well as in ISO 20338 and EN 16750 for oxygen reduction systems.

A clever mix of fire detection, fire prevention, fire fighting, for example in the form of two-stage concepts, and elements of organizational fire protection can also provide solutions that lead to the achievement of the defined protection goals even for these materials.

Are there any other questions you would like to ask? - Feel free to contact us!

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