By Katharina Buehmann. Permanent availability of data, 24/7, for 365 days of the year: For data centre operators and their customers, this commitment is highly significant. Restrictions or interruptions in data availability can result in business losses and enormous damage to the company’s image. The design specification, as per VdS guideline 2380, stipulates that, in the event of fire, all energy sources and operating equipment such as air conditioning systems, must be switched off, unless suitable measures are taken to minimise the risk of reignition. In this case, data availability is interrupted and the processes are stopped abruptly.
Data centres seek to prevent this, even if the data is also kept and processed redundantly. This means that if data centre operators do not want to, or cannot afford to allow interruptions under any circumstances, they will need a suitable solution, for reliable fire protection – without having to switch off the power and without the risk of reignition. The WAGNER Group offers a fire protection solution with the highest possible safety level: with the earliest possible detection of fires and regular checking of room integrity, an extinguishing oxygen concentration that can be maintained for as long as required, and with on-site refilling of the gas extinguishing cylinders with nitrogen.
Notifications can also be sent to the smartphone of the person responsible.
Prevent fire reignitions without switching off the power
Current fire protection solutions in data centres are generally based on gas extinguishing systems. These are mostly designed and installed with safety reserves greatly in excess of the actual number of nitrogen cylinders needed to extinguish a fire. An additional extinguishing capacity of around 40% of the calculated requirement is generally provided. This ensures that a sufficient concentration for extinguishing can be achieved for a limited time – even if the protected area has leaks, resulting from structural work, for example. The drawback with this solution, however, is that reignition cannot be effectively and reliably prevented, unless the power is disconnected, particularly after the end of the ten-minute hold time for the extinguishing concentration stipulated by VdS. In the worst case, the fire could reach its previous level again and may even spread further. This solution was one the data-centre operator Telehouse Deutschland GmbH was not willing to implement. They searched for a better alternative – and found it.
Frankfurt am Main is home to one of the largest data hubs in the world: the Deutsche Commercial Internet Exchange (DECIX) with peak data volumes of 6,7 terabyte per second. Telehouse Deutschland GmbH operates one of the largest data centres in Frankfurt, which has a direct connection with DECIX. The site is subject to the highest security requirements, as countless transactions of Cloud providers, online providers, travel agencies, insurance companies etc. must still run smoothly even in the event of a fire.
The Telehouse decision makers want to make sure that the highest security requirements are met. This applies to all aspects of security technology, right through to fire prevention. An interruption in data availability due to loss of power caused by fire would have severe consequences – for Telehouse customers, their customers and for the data centre operator itself.
Colocation service is used by sector giants
As a colocation provider, Telehouse Deutschland GmbH provides its customers with a data centre space with the corresponding physical infrastructure. This includes all electrical and air conditioning facilities, property management, security and fire prevention. The customers, who are mainly international Cloud providers, sector giants in the field of E-Commerce and entertainment, as well as other large service and industrial companies, use their own IT racks in the data centre. And these aren’t just a significant addition in terms of weight - a server rack can weigh up to two tonnes: "A rack can easily cost one million Euro. But the data stored on it is several times more valuable", explains Asko Hamberger, Safety and Security Management at Telehouse GmbH. "It is therefore extremely important that we keep our customers’ servers in operation 24/7". And individual fire prevention is a major part of this. "In environments with a high level of technology, always something can go wrong."
Fire prevention for technology buildings was not covered by legal requirements
When planning new data centre areas in an existing Telehouse building three years ago, Telehouse had its own technology building built for the required technical infrastructure. The technology building is connected to the existing building, via two central supply corridors. The supply lines for air conditioning and power supply, which are essential for operation, are located in two mezzanines of the building with room volumes of 730 and 1,700 m3. The Telehouse data centre uses as much electricity per year as a town of 30,000 inhabitants. Yet, despite the high volumes of electricity flowing from one building into the other, the fire prevention concept for the technology building did not include fire prevention – neither detection, nor extinguishing measures, not even for the two highly sensitive mezzanines. „But that is an extremely important part of our site. If a fire breaks out, the consequential damages for us and our customers would be enormous", says Hamberger.
Two-stage oxygen reduction concept
Telehouse therefore searched for a suitable fire prevention solution for the two essential mezzanines on its own. The first idea was active fire prevention through oxygen reduction. However: "A fire prevention solution with a permanently reduced oxygen level, didn’t seem like the optimal solution for us, as this would mean that the area can only be accessed by health-medically examined personnel", explains Hamberger. "We had to find an alternative, which also had to cover the following security goals: Constant accessibility (for planned maintenance work, repairs, searching for causes), no switching off the power in the event of a fire, fire prevention in place at all times (systems not switched off for maintenance work, for example) and a high level of security against false alarms." Eventually, Telehouse drew the planner’s attention to the WAGNER Group, which offered an intelligent solution: the two-stage concept. „That was exactly what we were looking for", said Hamberger, who was convinced by the demonstration of the solution in the WAGNER Group fire laboratory.
Strong connection: Proven gas extinguishing technology with oxygen reduction
The two-stage concept combines gas extinguishing technology with oxygen reduction and earliest possible fire detection to create an intelligent fire prevention solution with maximum safety. If the highly sensitive TITANUS® air sampling smoke detectors detect a fire in the earliest stages, the oxygen level is reduced first of all from 20.9 vol.-% to 17 vol.-% by gently introducing nitrogen from stored pressurized vessels. Reducing the oxygen concentration significantly reduces the fire behaviour, meaning that the fire should ideally go out at this stage. An OxyReduct® P-Line then maintains the lowered oxygen level of 17 vol.-% for as long as necessary by generating nitrogen on site. This means that Telehouse employees can look for the cause of the fire and remove it thanks to the freely accessible protected area. If the TITANUS® devices still detect a fire, the oxygen concentration is lowered once again; this time to 13.8 vol.-%.
At this oxygen level too, Telehouse employees can still access the protected area to remove the cause of the fire. The OxyReduct® P-Line maintains this level for as long as necessary.
The functioning of the two-stage lowering to the minimum oxygen level of 13.8 vol.-% was verified with mock flood drills, reports Project Manager Marco Bachmann. And the test can be repeated at any time using the installed solution.
On-site refills: Minimum expense, maximum security
The gas extinguishing vessels emptied during the mock flood drills can also be refilled on site in the future. The nitrogen generator (P-Line) is used for this, which generates the required inert gas with maximum purity and fills it into the emptied gas extinguishing vessels via a high-pressure compressor. "With the number of vessels we have, having them filled externally would cost around 75,000 Euro. We wouldn‘t be carrying out a mock flood drill at that cost, explains Hamberger. With the N2FILL solution, the mock flood drills incur no extra cost and the fire prevention system also doesn’t need to be switched off.
This guarantees maximum protection for the assets of both Telehouse and its customers at all times. "It’s an all-round great solution that completely fulfils our requirements", underlines Hamberger, who, by the way, is also privately involved with the subject of fire: He takes a leading position in the volunteer fire brigade of his hometown.
Advantages of the two-stage fire protection for data centres
- Almost no energy costs in normal operation
- No power shutdown necessary
- Top reliability thanks to regular checking of the leak-tightness of the overall system
- Highly effective fire suppression at all times
Katharina Buehmann: Qualified social scientist, newspaper editor, marketing editor for WAGNER Group GmbH
The article was published in FeuerTrutz International, issue 1.2019 (January 2019).
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