Testing Every Angle for Clients

FM Global ensures cost-effective sprinkler protection

FM Global Sloped Ceiling Sprinkler Test

FM Global Sloped Ceiling Sprinkler Test

A sloped ceiling test–the ceiling was inclined at 18 degrees and obstructed ceiling construction in the form of 300 mm (12 in.) purlins and 610 mm (24 in.) girders were present.

It pays to follow construction trends and look at fire protection from every angle. That’s how FM Global ensures optimal cost-effective protection for clients. 

Over the years, warehouse design has become increasingly complex. One such complexity is driven by the trend for greater natural lighting within industrial facilities. A common architectural means to achieve this goal is to provide buildings with windows built into sloped roofing systems where the roof slope exceeds 10º. While these roofing structures can be both aesthetically pleasing and allow sufficient natural sunlight within the building, they also create a major challenge for ceiling sprinklers to provide fire control. 

Why? Because excessive ceiling slope and sometimes the presence of ceiling structures like purlins and girders can potentially increase the time it takes for ceiling sprinklers to operate and make fire control a challenge. Unless properly accounted for, excessive ceiling slope can also redirect sprinkler spray away from the fire area and reduce the amount of water that gets applied to the point of fire origin.

To determine how storage occupancies can be protected by ceiling-only sprinkler systems, the company built a large-scale, fully adjustable sloped ceiling structure at its Research Campus in West Glocester, Rhode Island, USA. Researchers conducted systematic computer modeling to determine large-scale fire test parameters. Using the steel-beam sloped ceiling test structure, scientists could quantify the effect of ceiling slope and construction elements like purlins and girders on sprinkler protection design. 

The new scientific research findings are available in a technical report, “Sprinkler Performance under Sloped and Obstructed Ceilings,” written by Prateep Chatterjee, senior lead research scientist at FM Global.

This study concludes the multiyear collaborative research conducted by FM Global and the Fire Protection Research Foundation (FPRF), the research affiliate of the National Fire Protection Association (NFPA). Remarkable progress was made possible due to the collaborative nature of the work; three reports detailing the modeling and additional testing work have also been published. 

The time and resources spent on this full-size steel beam structure is well warranted. Chatterjee explains, “We built it to ensure that no questions remain after the tests.”

Sloped Ceiling Build Time Lapse

Sloped Ceiling Build Time Lapse

Watch time lapse of the sloped ceiling steel structure under construction at the FM Global Research Campus. The 15.2 m (50 ft) tall structure took seven weeks to assemble.

Cost-effective fire protection

FM Global clients will greatly benefit from these new findings. Weston C. Baker, senior engineering technical specialist for fire hazards & protection at FM Global expanded on this, saying, “Our current guidelines limit the installation of ceiling-only sprinkler arrangements for the protection of storage occupancies to a maximum ceiling slope of 10º. For ceiling slopes in excess of this cutoff, clients had to either install flat false ceilings over the entire storage area or supplement the ceiling sprinklers with in-rack sprinklers.”

Accepting steeper ceiling slope is great news for our clients, as Chatterjee outlines. “Any time you ask a client to redo the ceiling design, it can be very expensive and time-consuming. And the in-rack sprinkler option requires piping within the storage racks, which can interfere with the client’s material handling operations. Because of these tests, we no longer require those recommendations in ceiling slopes less than 18º.” Chatterjee explains, “We are now doubling the slope allowed for ceiling sprinklers from 10º to 18º.”

FM Global and the NFPA are in the process of adopting the study results into their respective standards. 

Download “Sprinkler Performance under Sloped and Obstructed Ceilings”

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