Understanding fire safety codes as they relate to battery installations in data centers is important for the following reasons:
- Knowledgeable individuals allow themselves more flexibility when selecting a battery solution. For example, data center professionals who are unfamiliar with the codes may find themselves paying for and installing safety equipment that is not required by law.
- Knowledge of the code can limit liability should a disaster occur.
- Fundamental knowledge of the code can help buy peace of mind. Data center professionals encounter enough complexity in their jobs without having to harbor doubts as to whether their battery system installations violate local fire codes.
A code is law–a mandated ordinance, regulation or statutory requirement enforced by a government or its agencies. Codes are enacted in order to protect public health, safety, and welfare. Codes are enforced by the “Authority Having Jurisdiction” (AHJ). This can be an organization, an office, or a single individual responsible for enforcing the requirements of a code or standard, or for approving equipment, material, an installation, or a procedure. In an environment like a data center, jurisdictions for the enforcement of a code sometimes overlap. For example: the building code may apply to seismic construction and floor loading; the fire code may apply to the use of flammable substances; the mechanical code may apply to ventilation and exhaust; and the electrical code may apply to equipment installation and safety.
This paper will look primarily at fire codes in the USA as they are usually the driver during battery system installations for the application of other codes (such as mechanical and electrical codes). Fire codes for stationary lead acid batteries were originally written to address large systems utilizing vented (also called “flooded” or “wet cell”) lead-acid batteries that supported data centers and network rooms. These systems are often located in a separate room away from the servers on the data center floor. These batteries continuously vent hydrogen gas and contain electrolyte in liquid form. Special ventilation and spill containment systems are required when these battery systems are deployed.
Smaller and distributed back-up power systems are typically located much closer to or within the equipment they protect (e.g., they are often located in racks next to servers). They generally use valve-regulated lead-acid (VRLA) batteries. VRLA batteries are designed to recombine hydrogen and oxygen and emit only extremely small amounts of hydrogen under normal operating conditions. Normal room ventilation is usually sufficient to remove any emitted hydrogen, so special ventilation is typically not required (see White Paper 32, Battery Technology for Data Centers and Network Rooms: Environmental Regulations).
The electrolyte in a VRLA battery is not in liquid form but is immobilized. The most common technology in the USA, termed “Absorbed Glass Mat” (AGM), uses a highly porous, non- woven glass mats that immobilize the electrolyte and prevent it from spilling. Another type, more common in Europe and Asia, uses a gelled electrolyte with a consistency similar to that of tar. A crack or hole in the casing of a VRLA battery will not result in a measurable electrolyte spill. Spill containment systems for installations with VRLA batteries are therefore not needed or necessary.
Fire safety regulations and their application to uninterrupted power supply (UPS) battery installations in the USA are reviewed. In some cases, fire codes do not clearly recognize improvements in battery safety resulting from changing battery technology. Valve regulated lead acid (VRLA) batteries are frequently deployed within data centers and network rooms without the need for the elaborate safety systems that are required for vented (flooded) lead acid batteries. Proper interpretation of the fire codes is essential in the design and implementation of data centers and network rooms.
- Code of federal regulations
- Fire codes
- Mechanical codes
- Application of the codes to battery technologies
Flooded batteries require special containment and ventilation due to the risks posed by their liquid electrolyte and their continual hydrogen generation. VRLA batteries have miniscule amounts of liquid electrolyte and generate much lower amounts of hydrogen. The latest codes specifically recognize the technology differences between flooded and VRLA batteries and exempt VRLA batteries from spill containment and occupational separation.
However, older codes might still be in use in many jurisdictions. The older codes were not as clear in making the distinction, and an inspector might take a very narrow interpretation. Since VRLA batteries contain miniscule amounts of liquid electrolyte, most practical installations of VRLA batteries do not trigger the spill containment and occupancy separation requirements. Battery systems based on VRLA batteries can be deployed, and are routinely deployed, within data centers, network rooms and work environments in compliance with fire codes.
White Paper Written By:
Stephen McCluer is a Senior Manager for external codes and standards at Schneider Electric. He has 30 years of experience in the power protection industry, and is a member of NFPA, ICC, IAEI, ASHRAE, The Green Grid, BICSI, and the IEEE Standards Council. He serves on a number of committees within those organizations, is a frequent speaker at industry conferences, and authors technical papers and articles on power quality topics. He served on a task group to rewrite the requirements for information technology equipment in the 2011 National Electrical Code.
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