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November 22, 2011

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Fire safety – For your information

It used to be said that money makes the world go round but now that we are firmly in the age of information technology, data has taken over as the globe’s primary rotational engine. It is therefore crucial, explains Udo Meinhold, to protect data centres from their greatest threat – fire.

Data, be it corporate, customer, employee, or personal information, are the lifeblood of an organisation. Reliable and continuous access to information allows companies to conduct their daily operations – selling their products, systems and services, responding to customers’ enquiries, collaborating with business partners, and keeping employees informed.

Consequently, protecting data to minimise service interruptions is crucial. Few companies are willing – or financially able – to house their own data so storage is usually outsourced to data centres. Here, it is not only obvious threats – such as hardware failures and power outages – that have to be guarded against but also physical hazards, such as sabotage and, particularly, fire.

Housing, as they do, such sensitive and vital information systems, which are essential to the survival of their clients, the threat of fire should not be under-estimated. More than most other structures, data centres require absolute protection but also present a greater level of risk of fire. About 6 per cent of infrastructure failures in data centres are related to fire.

The electrical power and extensive cabling that drive the computing systems provide a constant source of potential ignition, particularly under raised floors, and the many thousands of plastic components used in data-centre infrastructure supply a plentiful source of combustible material.

Both passive and active fire protection is therefore particularly relevant in such vulnerable locations. Even a smouldering fire, without flames, can damage hardware through soot, corrosion and the release of toxic gases, so the time between the initial outbreak of fire and successful extinguishing after detection is the critical factor in preventing operational failure of a data centre.

One of the main causes of fire-safety system failure is problems in the interaction of detection, alarm, control and extinguishing systems, so such systems must be fully compatible with each other. A system with real interoperability from a single source is ideal.

In data centres, heavy power loads, or a defective piece of equipment, can quickly lead to overheating, or a short circuit. A typical fire will start slowly, with a long period of overheating and smouldering before flames break out. To avoid this, early smoke detection is required. However, a specific issue in data centres is that, with the level of data growing all the time, the layout of equipment in data centres is becoming more dense. This means that servers require comprehensive cooling – up to 8600 watts/m2.

The upshot of this is that the greater level of air exchange will partly remove any smoke within the airflow, thus making early detection by traditional systems more difficult. It also increases the risk of the fast spread of fire to other areas.

Consequently, aspirating smoke detection will provide the earliest possible warning, even when the smoke is barely discernible to the naked eye – or nostril! Air samples can be continuously taken at danger spots (usually in the circular airflow, and among the server racks) and, as soon as smoke particles are detected by the sampling device, a pre-alarm or alarm – depending on the smoke concentration – is triggered.

Shutting down equipment at the earliest indication of fire will stop the development of corrosive combustion gases. In a ‘gentle’ shutdown, intelligent server management will be activated to divert valuable data to neighbouring server racks. Final shutdown of power occurs only when the transfer of data is complete.

To prevent false alarms, two separate detectors should sound an alarm before the extinguishing system is activated (a single detector will mean the system only goes into a state of pre-alarm). In case of fire, standard alarm sounders and sounder beacons should be used to alert the building’s occupants. A voice-alarm system with messages automatically activated by the fire-detection system will ensure precise information and instructions for are provided.

The choice of extinguishing agent and the method of its delivery are important factors in optimising protection in data centres. Because of the sensitivity of the IT infrastructure, a dry extinguishing system is essential. Water is generally not used as an extinguishing agent in data centres – the only exception being in generator rooms, where a combination of gas and water is used because of the thermal risk.

The two most suitable types of gas extinguishing solutions for data centres are inert gas and chemical extinguishing agents. For medium to large-sized centres, a constant-discharge inert-gas system works well, as it will allow efficient extinguishing without pressure peaks. Chemical extinguishing systems, using fire protection fluid, are more suitable for small to medium-sized centres. The fluid floods the room in seconds and starts extinguishing the fire before any electronic equipment is severely damaged.

With fire-protection fluid extinguishing systems, nozzle pressure and height are important. A minimum pressure of 10 bar ensures the best evaporation and even distribution of the extinguishing agent – this is essential, as although the fluid is in liquid form the extinguishing takes place in the gas phase. A minimum pressure of 10 bar is also recommended when extinguishing with inert gases, as this will mean an ideal mixture of the extinguishing agent with the surrounding air, leading to fast and reliable extinguishing.

In rooms with ceilings higher than five metres, installing a second pipe layer with nozzles is recommended, to ensure a fast and even distribution of the extinguishing agent. The maximum recommended coverage of nozzles is 30m2. In rooms with an area greater than this, there is a danger of ‘swirling’ of the extinguishing agent. Large areas of nozzles can also mean more agent is released. If chemical extinguishing agents are being used, a very high discharge volume per nozzle can prevent complete evaporation of the agent.

Summary
Data centres are the beating heart of many companies’ information infrastructures, so it is crucial that they are protected to the highest possible level, particularly from the threat of fire. A complete solution, in which detection, alarming, evacuation and extinguishing are fully integrated and suitable for the electronic equipment-heavy and power-dependent environment, is the key to robust danger management in these power-houses of today’s world.    

[PANEL]

Case study – SafeHost

Geneva-based data-centre manager SafeHost began operations in 2002 and is now one of the leading providers of data-centre and workplace-recovery services in Switzerland. Its portfolio includes comprehensive IT services, ranging from simple dedicated servers to business continuity and managed IT services.

SafeHost’s 5000m2 Tier III data centre in Geneva now houses some 12,000 servers and storage devices, containing the data of more than 140 customers, who include international aid organisations such as the UN and the Red Cross, banks HSBC and Barclays, and telecoms giants IBM and Swisscom. In total, SafeHost currently stores more than 1 Petabyte (1000 Terabytes, or 1 million Gigabytes!) of data.

Five of the six storeys in the SafeHost building are occupied almost entirely by IT equipment. The building is divided into 350 fire-detection zones, with some 830 highly-sensitive detectors from Siemens’ Sinteso and AlgoRex ranges in use. These are supported by around 30 aspirating smoke detectors, which continuously analyse the room for smoke particles. In addition, some 50 manual call points are installed in strategic locations throughout the building. In an emergency, 65 alarm sounders make sure the building is evacuated quickly.

In terms of extinguishing, the building is divided into 21 sectors, each equipped with its own extinguishing system, comprising gas tanks, a piping network, and an extinguishing control panel. SafeHost uses the Siemens Sinorix N2 gas system. If the detectors detect and confirm a fire, the system automatically activates the extinguishing process. Valves on the gas tanks in the basement of the building are opened and nitrogen – an inert natural gas – flows through a complex piping network to the room where it is needed. There, the nitrogen displaces oxygen, thus robbing the fire of one of its essential components.

Says SafeHost CEO, Gérard Sikias: “Our highly-secure building and our protected IT infrastructure allow us to offer our customers business-continuity services on site. If a customer’s IT, or building is no longer usable after an extraordinary incident, their employees can temporarily move into our building. Since we have the necessary infrastructure, and the customers’ data are already here in the form of back-ups, the customer can resume their business activities within a very short period of time. In some industries, this service can ensure a company’s economic survival.”


Udo Meinhold is senior marketing manager for the Fire Safety and Security Business Unit at Siemens Building Technologies Division.

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