Mission Critical Fire Safety
Best practices for installing fire suppression systems in data centers.
The data collection and cloud computing industry has seen tremendous growth in recent years, and that growth has been a boon to the construction industry, which is being called upon to design and build these structures to accommodate complex mechanical needs. Chief among these needs is a reliable and effective fire protection system that will ensure mission-critical technology like servers are always operational.
The challenge, however, is that owners and contractors often fail to consider fire protection installation until late into a project. That may not be a big problem for a relatively simple construction project, such as an open-air shopping center, but in a data center that is holding millions of dollars of equipment, with a labyrinth of mechanical elements above the ceiling and beneath the floors, it is especially important to consider the installation of fire protection early in the design process.
When proper planning and preparation is not practiced, we often see one or more of the following scenarios play out.
- Last minute changes to the fire protection system requested by the owner leads to project delays and unexpected costs
- The layout of the building, including how tenants are oriented in the space, changes from the initial design specification, resulting in major alterations that need to be made to the fire protection system
- Rework is required because the proper amount of room was not allotted for the fire protection system in the ceiling plenum
- A backlog at the approving authority’s office delays regulatory approval of the as-built documentation, putting the project on hold, and delaying project completion
Fortunately, there are ways to avoid these pitfalls through planning, awareness, and coordination in a few specific areas.
INCLUDE A FIRE SUPPRESSION CONTRACTOR IN THE DESIGN PHASE
Fire suppression is often one of the last trades to be considered and one of the last contracts awarded. This is probably the biggest reason for problems in installation of such systems. Indeed, fire suppression and fire alarm documents are generally “deferred submittals,” documents that are not submitted to regulators when the main building permit is submitted. A better way to handle this is to have architects and engineers include fire suppression contractors in the initial design process. During this process, they should look at the access doors in the ceiling, the locations of mechanical/fire riser rooms, locations of drains, and building blocking and stacking.
Other important questions to ask at this phase include:
- What is your fire vs. supervisor alarming method?
- When will you require evacuation and is your strategy code compliant?
- Have you allowed enough space for all of the required fire protection devices, lighting, and HVAC?
Several data centers install wet pipe sprinkler systems during the core and shell phase of a project. The wet system fire riser assemblies are converted to double interlock pre-action systems during the tenant finish out phase. There must be a well-defined plan on how to maintain other portions of the building when the conversion of the system takes place.
When a building has several pre-action systems due to segregation of spaces, the fire riser room should be located as close to the center of the areas being protected as possible. This location selection will help mitigate the possibility of not meeting system trip times (commissioning as required by NFPA 13).
HAVE A CLEAR UNDERSTANDING OF THE REGULATORY LANDSCAPE
Each regulatory agency, also known as Authorities Having Jurisdiction (AHJ), has a unique set of rules and regulations governing fire protection. They usually follow a base set of guidelines that are fairly consistent across the country. But they also include unique requirements based on the needs of their jurisdiction. It is these unique requirements that often catch builders by surprise.
An example of such a situation is the hazard classification of the area being protected by the fire suppression system. One jurisdiction may allow a data center to be considered a “light hazard,” while another may deem the same data center an “ordinary hazard group I.” The difference has a significant impact: it would increase the required pipe size, the number of sprinklers, and the sprinkler location. Larger pipe sizes have a significant impact on a key area of the system — the time it takes to trip the system since the volume of air in the system can prolong the time it takes to trip the system into action.
EMPLOY BEST PRACTICES FOR CLEAN AGENT AND PRE-ACTION SYSTEMS
Most high value data centers will use a two-pronged fire suppression solution. The first line of defense will often be a clean agent system utilizing a non-corrosive gaseous means of suppressing a fire. The second line of defense is generally a double interlock pre-action system. In addition to the fire suppression and fire alarm systems are the mechanical and electrical systems. The coordination between these systems and the owner’s needs is critical.
For clean agent systems, make sure you choose the right edition. Clean agent system design has several areas of potential impact. It is important to verify which edition of NFPA 2001 (Standard on Clean Agent Fire Agent Fire Extinguishing) is applicable as there are differences in the requirements from year to year.
One of the most extreme examples of these changes includes the increase in design concentration from the 2008 to the 2012. The location of the clean agent notification devices should also be discussed with the enduser and AHJ to accommodate any visual obstructions related to their operations. For example, if you only have a few egress doors, you may need more strobes to meet operational needs. Also, do the abort stations meet the safety needs of the facility?
The location of the clean agent tanks can drastically impact the number of clean agent tanks required. The location of the clean agent discharge nozzles is also important as related to the heat containment configuration. If the nozzle placement is not checked against the actual operation and configuration, the design concentrations may not be met. When clean agent system nozzles are required above the ceiling, bracing can present new challenges. Is the clean agent wiring the responsibility of the fire alarm contractor or clean agent contractor? Although they are simple, scope gap can create project chaos.
The server cooling method also must be clearly defined. There are a variety of heat containment designs. These designs affect the location of the clean agent notification devices and abort switches and the amount of clean agent. The different designs have different airflows and air changes causing impacts to the gaseous protection. Has the removal of the clean agent gas after discharge so that the area can be placed back in service been considered? What is the design objective and how quickly is this gas evacuation to occur?
MAKE SURE THE INSTALLATION RESPECTS TENANT BOUNDARIES
Every data center has critical design requirements such as pipe routing and fire riser assembly location. The routing of the sprinkler systems must be coordinated with potential tenant boundaries. Tenant boundaries are less susceptible to change in data centers than they are in areas such as malls or retail spaces, but must be considered. It is important to consider this when routing the sprinkler system piping through the facility. The architectural wall layouts must provide an avenue to get water from one part of the building to another without interfering with tenant boundaries. Questions you should ask during this phase include:
- Is it acceptable to route sprinkler piping serving one tenant over/through another tenant?
- What are the ramifications of having this type of arrangement?
- If there is a fire in one isolated tenant area, do you want water to fill the piping in tenants that were not at risk by the fire?
- Will the building management system be required to monitor the suppression systems as well as your supervisory air status?
- Pre-action systems generally use fire alarm devices as a portion of their system releasing method. The location and type of the pre-action system releasing devices such as heat or smoke detectors must be thoroughly addressed. The proper technology must be used in the right application.
FAVOR BLACK STEEL PIPING OVER GALVANIZED PIPE
The use of galvanized pipe for pre-action systems against corrosion is becoming a thing of the past while inert gas protection of black steel piping is becoming the new norm. NFPA 13-2013 requires galvanized piping to be calculated based on a C-factor of 100 in lieu of the C-factor of 120 in previous additions. C-factor represents internal pipe friction characteristics as the pipe ages. The C-factor change makes the use of galvanize piping less attractive. The use of galvanized pipe is also not allowed in the Department of Defense projects that utilize UFC 3-600-01 design criteria. Section 4-2.3.2 states, “Galvanized piping is not permitted to be used in dry pipe, preaction, or wet pipe sprinkler systems.” Section 4-18.104.22.168 states, “For Navy and Air Force, nitrogen shall be used in lieu of air for preaction systems.”
There is less desire to use galvanized piping because it costs more, there are application restrictions, and there is more evidence that galvanized pipe does not actually provide a higher degree of corrosion protection in fire protection systems.
STRATEGICALLY LOCATE THE SPRINKLER SYSTEM AND AIR COMPRESSOR
The location of the sprinkler system must also be clarified and justified. Are sprinklers located above the ceiling of the space, within the area containing servers, and or below the raised computer floor? The air compressor selection is important. Should you use an air compressor with or without a tank? Ensure that the air compressor selection does not cause constant cycling of the equipment. This will limit the life of your air compressor and could leave your system out of service. It is important to consider the means and methods of conducting tests for the pre-action systems. Has all of the testing been considered during design and not as an afterthought? If testing was not considered, there could be a major cost implication.
In conclusion, it is critical to select the right partner in the fire protection systems design and installation. Although the fire suppression systems are a lower contract value than other disciplines, failure to properly incorporate them into the design team adds increased cost and overall frustration. The current permitting process in many jurisdictions fosters this approach. The owner and design team must be focused on the issue and not allow the status quo to remain acceptable. There are cost savings, innovation, and overall project ease at stake. Failing to include the proper team members is a lost opportunity.
The installation of fire suppression systems in data centers can and should be a predictable and smooth process. The key is getting the right experts involved early in the process so potential pitfalls can be identified and prevented through smart planning, coordination, and problem solving.