Author(s): Jesse Roman. Published on September 5, 2014.

LIKE SOME THEORIES OF EVOLUTION, water mist technology moved from sea to land. The first applications for mist were in enclosed compartments aboard ships, and then throughout cruise ships in common areas such as shops and restaurants. Because water mist uses up to 90 percent less water than sprinklers, the technology allowed boats to travel lighter without taking on heavy and destabilizing loads of water.

Mist made landfall in the 1990s when the systems were installed in the compressor rooms, turbine enclosures, and machining spaces owned by petroleum producers in Alaska’s North Slope, according to Jack Mawhinney, a senior engineer at Hughes Associates and a water mist expert who has been involved in research and development in the industry since 1990.

“Around that time there were dreams and visions of using water mist to replace sprinklers in other land-based applications,” said Mawhinney, who for years has served on NFPA’s Technical Committee on Water Mist Suppression Systems, and was chair of the committee when the standard was first developed. “But it has been a long and difficult evolution to get there.”

Today, water mist has four main applications on land: data centers, large commercial cooking facilities, industry and energy facilities, and cultural heritage properties, according to Adam Tracy, a regional sales manager at Marioff, the world’s largest manufacturer of water mist fire suppression systems.

Because the systems use much less water, mist is also useful in areas with unreliable water supplies. The international hotel chain Marriott, for instance, has installed the systems at select hotels around the world in places where water can be difficult to come by.

Cultural inclinations

The water mist industry’s bread and butter, however, remains the industrial and energy sectors, followed by cultural heritage properties, such as St. Patrick’s, Tracy said.

Nick Artim, a principal at Heritage Protection Group and a longtime member of the NFPA Technical Committee on Cultural Resources, works exclusively in cultural heritage buildings and took part in designing and installing the water mist fire suppression systems at Monticello—Thomas Jefferson’s home in Charlottesville, Virginia—and in the former home of James Madison. For buildings that house important collections—or, like Monticello or St. Patrick’s, are pieces of art themselves—water mist systems offer an alternative protection measure to sprinklers. While NFPA 909, Protection of Cultural Resource Properties—Museums, Libraries, and Places of Worship, and NFPA 914, Fire Protection of Historic Structures, advocate installation of sprinklers, both codes permit water mist as an alternative where approved by the authority having jurisdiction.

As a result, fire suppression systems using the gas Halon 1301 were used for years in places such as museums and libraries. Halon had become popular in such applications because it could extinguish a fire without irreparably damaging the delicate and often irreplaceable objects inside. Production of Halon was banned by the U.S. Environmental Protection Agency in 1998, however, after it was shown to deplete the earth’s ozone. The gas has also been shown to strip paint and cause other damage, Artim said.

As an alternative, “water mist really became the great link between gas and traditional sprinklers,” he said.

High-profile water mist installations such as Monticello and St. Patrick’s Cathedral have also helped speed up adoption of the technology in other cultural properties, Tracy said.

“Four or five years ago, you’d say water mist and people didn’t know what you were talking about,” he said. “Now people know about it and they understand it. Big projects pull in a lot more interest and open people’s eyes to seeing the possible applications.”

Mawhinney, who called the St. Patrick’s installation “a high mark” for water mist technology, agrees that the best is yet to come.

“There have been little milestones along the way, and there has been so much work to get the American building and fire codes to be more accepting of the possibility to use water mist,” he said. “I think in the next five years we’ll absolutely see more applications.”

Even as water mist’s popularity grows, U.S. codes—including NFPA 1, Fire Code, NFPA 13, Installation of Sprinkler Systems, NFPA 101, Life Safety Code, and NFPA 5000, Building Construction and Safety Code—do not consider water mist systems to be the equivalent of traditional sprinkler systems in controlling or suppressing fires. Those in the water mist camp claim the technology works as well in most areas, and even better in some situations. Others argue water mist is unproven and needs more comprehensive testing before it can be considered a safe and suitable alternative to traditional sprinklers in all applications.

Artim says stakeholders—engineers, contractors, designers, manufacturers, and others—need to make time to educate the fire protection community on water mist. “For many people this is still very new,” he says. “I can understand the reluctance. When you tell a fire chief that the system operates at 1,000 psi, their eyes light up and they think, ‘Well I don’t want that in the building.’”

Jesse Roman is staff writer for NFPA Journal.