Reprinted from FIRE AUSTRALIA Summer 2015
Since its creation in 2007, Canberra Data Centres (CDC) in the Australian Capital Territory has used the latest technology to be as efficient, green, secure and reliable as possible.
When it came to choosing a fire-suppression system to install across multiple zones, the company wanted a solution that was in keeping with its green ethos, cost-effective, would cause minimal disruption in the event of any incident and would not affect the facility’s excellent up-time record during installation.
The Victaulic Vortex 1500 Hybrid Fire Suppression System has been their solution and is now provided as a base service to all the data centre’s clients.
“This system demonstrated the qualities that are needed for fire suppression in an ICT environment,” said Peter Henson, Chief Technology Officer at CDC. “Additionally it meets the ‘value for money’ criterion we were looking for.
“The ‘stand up’ time from an incident to business as usual is significantly reduced compared to traditional fire suppression,” said Mr Henson. “In testing, it has been demonstrated there is no damage or residue following deployment.”
Equipment enclosures, commonly found in data centre and electronics facilities, present significant fire suppression challenges and are considered local application hazards. Traditional single-agent water mist systems often need to be installed directly within an enclosure to suppress a fire. An internal installation would require the equipment to be de-energised before a water-mist system discharge occurs in order to prevent damage and injury.
If fire suppression is required in a larger area, where multiple enclosures or pieces of equipment may need to be protected, this is considered a total flooding application. In a total flooding scenario, the water mist concentration that enters an enclosure will not be great enough to cool and suppress the fire.
In either scenario the equipment inside the enclosure would be subject to extreme wetting conditions along with possible damage.
The system CDC now uses delivers a blend of water and nitrogen to suppress and extinguish local application and total flooding fires. It is effective for small, smouldering enclosed fires and large, heat-releasing fires in open spaces.
With nearly zero wetting, the system is especially suited to the CDC’s requirements.
Although the preconception exists that water cannot be used in information technology equipment areas, testing has shown that water can be deployed in this hybrid nitrogen-style discharge and be extremely effective, even in very small amounts, using very tiny particles. In tests, data was not lost and no hard drives were damaged by the discharge from the suppression system.
Much of the system’s innovations lie in the emitter. Using proprietary supersonic atomisation technology, the emitter atomises the water, forming a dense homogeneous suspension of nitrogen and water. The average droplet size is around 10 ?m, and the minimal amount of water released per emitter—as little as a gallon/min or 1 L/min—essentially eliminates any wetting in a space.
The system uses 97% less water than high-pressure water mist systems. The tiny droplet size means there is a hugely increased heat-absorbing water droplet surface area.
The system was installed by Wormald Fire Systems (ACT), which works closely with Fire Protection Technologies, Victaulic’s international distributor of Vortex in Australasia.
Since the system extinguishes fires in open, naturally ventilated areas, maintaining room integrity is not essential and annual fan testing of the enclosures is not required.
This feature made installation easier and there was no disruption to ongoing data centre operations. Proper room integrity for many inert gas systems requires custom construction to control airflow. Sealing a room to meet specified leak rates can be a challenge for facility owners and contractors.
When a system is installed in data centres, system emitters should be placed so that they do not directly impinge on the device. The preferred installation practice is for emitters mounted in a sidewall configuration and arranged so that the blended suspension of water and nitrogen will be directed down hot and cold aisles.
High velocity and low pressure creates a uniform blend of water and nitrogen. Water is introduced to a jet stream of nitrogen at supersonic speed then delivered with the nitrogen into the protected space at 65 km/hour. This swirling, vortex-like distribution fills the hazard space and quickly extinguishes the fire with little or no water residue. Electronics are kept dry and there are no toxic agents or chemicals involved.
The system’s green credentials also appealed to CDC. “Our approach to data centre delivery is that it should constantly strive to be as green as possible,” said Mr Henson. “All our site improvements are delivered to meet this green goal. The system discharge has no greenhouse [gas] footprint at deployment as it consists of water and nitrogen only. This fits in with CDC’s green and clean environmental philosophy and was certainly a contributing factor to its selection.”
The centre keeps spare nitrogen bottles on site so that any of the four cylinder banks can be quickly put back on line in the event of a system discharge. Empty nitrogen cylinders can then be quickly recharged at any local industrial gas supplier.
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