Associate and manager of the fire protection services team at Norman Disney & Young, Damian Condello, outlines the role of a new technology recently introduced to the Australian market - Oxygen Reduction Systems.
As a fire industry, what is the reason we design and install fire suppression and detection systems to building environments? The answer is to initially detect a fire in its infant stages and to provide warning to occupants. Then, if a suppression system is installed, to extinguish the fire or limit the fire from spreading.
All current forms of fire detection and fire suppression systems rely on one simple fact, a fire must have already started for its design to be utilised. Fire is every business’ nightmare. Even a small fire can lead to considerable damage and downtime making it a serious risk to the business.
However, there is now a revolutionary fire prevention technology relatively new to the Australian market which prevents a fire from starting in the first place. Unlike your conventional fire suppression systems, which suppress or limit the spread of a fire after ignition, an Oxygen Reduction System is a fire protection technique that is not designed to extinguish a fire.
It is designed to prevent a fire from originating in the first instance and therefore can prevent damage from occurring.
The way that this product achieves this is by its ability to create an oxygen reduced or hypoxic environment, which prevents flame ignition by maintaining the oxygen levels in the protected space at non combustible levels and at the same time is safe for human occupants.
Inert gas suppression systems have been utilising this principle successfully for many years, by reducing the oxygen level in the room following a discharge after the fire has occurred. Fire will become impossible when the oxygen content of air is reduced by just a few percent.
An Oxygen Reduction System employs innovative technology that reduces the oxygen level in the room. Air with a reduced oxygen content (an oxygen content of approximately 15 per cent is standard for Oxygen Reduction Systems) is injected into the room to lower the normal oxygen content in the space from a normal ambient oxygen level of 20.9 per cent.
A space with an oxygen content of 15 per cent is perfectly suitable for human life but is not sufficient to support combustion or an ignition source, as most flammable solid materials and liquids cannot ignite in environments with an oxygen level lower than 16 per cent. Therefore, an environment of 15 per cent oxygen content will prevent an outbreak of a fire. Scientific research has shown that working in such hypoxic conditions does not impose any health hazards on healthy human beings.
It is important to note, however, that the manufacturers of these systems recommend that a person not be exposed to this hypoxic environment for more than four hours at any one time.
After four hours, the person should take a 30 minute break from the hypoxic environment before entering the protected space again.
There are various manufacturers of these systems available on the Australian market today. However, no specific manufacturer or supplier is referenced in this article.
The actual system set up varies slightly between manufacturers. However, the Oxygen Reduction Systems are essentially made up of compressor units, generator units, filters, buffer vessels, control unit or control centre and sensing elements in the protected space.
The control unit can be set up directly outside the protected space or at an alternate remote location if so desired by the client. The systems also have inbuilt batteries to ensure system operation even in the event of power failure. The plant requirements consume little space compared to conventional fire suppression systems.
There are basically two types of systems available. One reduces the oxygen content of the air in the protected space by the controlled injection of nitrogen, which is monitored by the sensing elements in the protected space. The other type of system draws ambient air at 20.9 per cent oxygen content into the hypoxic generator where it is purified and turned hypoxic.
It is this hypoxic air (approximately 15 per cent oxygen content) which is then discharged into the protected space where it is monitored by sensing elements. With all Oxygen Reduction systems, a control unit or control centre monitors the protected space with oxygen sensor elements to allow the oxygen level to be maintained at the desired level.
If, for whatever reason, the oxygen level in the room changes to a level which would cause concern, an alarm will generate on the control unit or control centre, ensuring that any issue can be rectified. The systems automatically monitor for faults. The equipment for an oxygen reduction system can also be monitored at the Fire Indicator Panel for the building and the BMS for alarms such as low oxygen fault, general fault and so on.
The system can also be monitored via text messages to dedicated mobile phone numbers if so desired. All systems can be configured as twin-systems, offering full redundancy by installing a second compressor and generator units, which will provide a N+1 arrangement to improve failure safety. This is important for rooms containing sensitive equipment.
It is important to point out right from the start that there is no Australian standard or Australian legislation for this type of system. However, it can be utilised in sensitive environments where a client may not want a fire to start in the first instance, as a complementary or supplementary fire prevention option above the traditional fire detection and suppression systems as required by the National Construction Code of Australia.
In any installation, at the very least, the protected space should also be equipped with sensitive smoke detection. This set up over and above the requirements of the National Construction Code of Australia is beneficial to clients who do not want any down time for their business. The system can easily be installed in already existing premises as well as in newly built spaces.
The system is extremely environmentally friendly as it only uses natural ambient air as its source, therefore no additional gases or chemicals are used. It is safe for people as it utilises breathable air avoiding any hazard to human occupants and any damage to protected rooms and its content.
This reduced oxygen content of 15 per cent is similar to what anybody travelling on a modern passenger airplane would experience, or what millions of residents experience in various cities across the world when living at altitudes of around 2700m or higher. The only waste product generated from an Oxygen Reduction System is a small amount of water.
Applications where this type of system may be beneficial are archive storages, frozen food storages, art galleries, data centres, electrical switch rooms and server rooms. It is important to understand that, similar to a gas suppression system, an Oxygen Reduction System requires the protected room or space to be sealed as well as possible and reasonably structurally sound to ensure the system can operate efficiently by minimising the permanent leakage of air in and out of the room.
If the room has substantial leakage, then the system has to work harder to maintain the oxygen content to the desired level as air is constantly leaking out of the protected space. A better sealed room means smaller equipment and therefore lower running costs.
All protected spaces proposed to have an Oxygen Reduction System installed must have split-type air conditioning systems or closed dedicated recirculating air conditioning systems. Ducted mechanical ventilation systems cannot be used in rooms containing an Oxygen Reduction System as the air change rate in the room would be constant, therefore making it extremely difficult, if not impossible, to maintain the oxygen level in the room at 15 per cent.
The initial outlay cost for an Oxygen Reduction System is greater than what would traditionally be budgeted for a fire suppression system. However, ongoing maintenance is less frequent and subsequently less costly than traditional fire suppression systems.