A Comprehensive Approach To Data Center Fire Safety
Fire protection for modern data centers is complex. The overall protection program needs to be based on the level of acceptable risk for the data center and meet the rigors of reliability and business continuity goals. A comprehensive protection program developed to address expected fire risks, rather than simply meeting local codes and regulations, provides a robust approach to meet these goals.
In today's data centers, power densities may exceed 400 watts per square foot, almost all of which is transformed to sensible heat by the servers, storage devices, and networking equipment located within the data center usable raised floor area (white space). Such power densities require significant quantities of air (3,700 cfm or greater) to provide cooling at typical design conditions. Fire detection and suppression systems designs need to account for the challenges posed by high airflow velocities associated with high power densities.
Overall reliability is critical as down-time of equipment can be catastrophic. Reliability can be improved by adding redundancies in data center equipment, fire protection equipment, and distribution systems. Table 1 (below) lists Uptime Institute industry tiered classification system. A facility designed to the Uptime Institute's Tier III standard, for example, has the resiliency to permit the removal of any element of a building system without impact to critical facility loads. This means that any pump, chiller, transformer, switchgear, pipe or cable can be taken out of service (e.g., for maintenance) and be transparent to the business.
Protection goals and objectives for data centers include life safety, property protection, and business continuity. Life safety is mandated by codes and standards and includes providing safe exits and adequate warning of fire or other hazardous conditions within the data center. Property protection and business continuity goals are largely based upon owner, user, and other stakeholder requirements. Property protection can be related to equipment damage, while business continuity goals can be related to system downtime.
Designing to typical code requirements will not necessarily meet property protection and business continuity goals. Holistic designs that consider fire ignition scenarios and design for these scenarios, rather than simply meeting the code requirements, address these goals. Such designs integrate systems into comprehensive fire protection programs, and incorporate requirements for building construction, fire- and smoke-rated walls and ceilings to protect the data center, interior finish limitations, egress provisions, and fire detection and suppression systems. NFPA 75, Standard for the Fire Protection of Information Technology Equipment outlines a comprehensive risk-informed approach to data center fire safety and protection.
Table 1: Uptime Tier Criteria
| ||Tier I
|Infrastructure Principle ||Basic ||Redundant ||Concurrently |
|Active Capacity Components to |
Support the IT Load
|N ||N+1 ||N+1 ||N After any
|Distribution Paths ||1 ||1 ||1 Active |
and 1 Alternate
|Concurrently Maintainable ||No ||No ||Yes ||Yes
|Fault Tolerance ||No ||No ||No ||Yes
|Compartmentalization ||No ||No ||No ||Yes
|Continuous Cooling ||No ||No ||No ||Yes
|(Source: Uptime Institute)