Water mist now viable for fire risks faced by modern data centers

The global market for data center fire detection and suppression systems stands at over US $1.4 billion, and projections show it more than doubling to over $3 billion by 2034. With uptime being the most critical operational factor for data centers, these types of systems (and many other loss prevention and mitigation products) protect facilities against the effects of fire and other potentially damaging hazards.

FM Approvals’ June 2025 certification of VID FIREKILL’s Low Pressure Water Mist System for non-storage occupancies, hazard categories 2 (HC-2) and 3 (HC-3) marks a pivotal turning point in limiting damage from fire incidents that disrupt operations in mission critical environments. Water mist has long been effective for specialized applications, and the lowest non-storage occupancy hazard category (HC-1), but it had never been certified for moderate and elevated occupancies. That left data center operators with limited options — able to protect certain spaces with water mist, but not the entire building.

The addition of lithium-ion battery backups directly alongside, or within, server racks elevated the hazard classification of white space to HC-2, requiring new testing standards to be applied and new innovations to meet them. Now, with the ability to protect HC-2 and HC-3 occupancies, water mist systems can provide full-building fire protection solution in the same way as traditional fire sprinklers, a milestone that provides more protection options for mission-critical environments and broader adoption of water mist technology.

Why data centers are uniquely fire-prone

Modern data centers are built for maximum capacity and efficiency, but the very characteristics that make them reliable also increase fire risk. Together, the following factors create environments where even a small fire can escalate quickly:

• Equipment density: Packing more servers and devices into smaller spaces concentrates heat and combustible material, while making suppression systems work harder to reach and cool ignition points.
• Lithium-ion battery integration: In 2018, operators traded in battery backup rooms for lithium-ion battery backups located alongside, or within, server racks. While this saves on real estate costs, lithium-ion cells can fail violently and release flammable electrolytes and intense heat to collocated equipment.
• High combustible loading from plastics: Server housings, cable insulation and other plastic components add fuel that burns intensely and at high temperatures.
• Bundled cabling and trays: Tightly packed cable runs act like pathways for fire, allowing flames to move rapidly across rows and even between floors.

Sprinklers have been the default for full-building protection from the above factors for decades. Water mist systems, while effective, were historically limited to niche applications or low-hazard spaces within a data center. FM Approvals introduced a data center-specific water mist protocol in 2016, which enabled protection of data processing rooms and halls in both above-floor and below-floor applications with water mist systems. Like traditional sprinklers, water mist is now a viable option to choose for full-building protection of data centers, including the higher-hazard white space.

What’s next for water mist manufacturers?

The certification of VID FIREKILL’s water mist system is sparking momentum across the industry. For those pursuing FM Approval’s certification, two considerations stand out:

1. Plan for testing demand. HC-2 and HC-3 evaluations take time to complete, and due to today’s demand for fire protection testing, FM Approvals’ fire test laboratory is often booked months in advance. Early scheduling is essential to avoid bottlenecks.
2. Understand the protocols. FM 5560: Examination Standard for Water Mist Systems addresses the unique hazards of modern data centers, with the addition of HC-2 and HC-3 fire test protocols. Manufacturers should align product development with these hazard realities to ensure smoother approval.

For now, HC-3 occupancies represent the leading edge of what is possible with water mist. Storage occupancies, ignitable liquid warehouses, and very high-challenge environments remain outside current approvals, though development is underway for some of these other challenging hazards. Hybrid suppression systems — such as those covered under FM 5580: Examination Standard for Hybrid (Water and Inert Gas) Fire Extinguishing Systems, which combine inert gas and water mist — are also adding new options to the mix.

Explore the entire Approval Guide to find FM Approved solutions relevant to data centers. You will find product information, engineering data, and technical information for more than 60,000 FM Approved products.

If your organization manufactures property loss prevention products, begin the FM Approvals certification process by applying for certification online or contact Jonathan Carpenter (FM Approvals, AVP, Technical Team Manager, Fire Protection) at [email protected].