Latest innovation in fire suppression technology -- K25 ESFR Specific-Application Sprinkler

NOTE: This information is from a previously printed press release, newsletter, or other dated document. It is presented here for archival purposes only.

1999: Using a new innovation in sprinkler technology that allows sprinklers to operate at lower pressures, the new ESFR-25 sprinkler, which operates at 15 versus 50 psi, is expected to improve the level of fire protection in many storage facilities.

UL has investigated and Listed the new Grinnell model ESFR-25 Specific Application Early Suppression Fast Response (ESFR) sprinkler. This sprinkler has a discharge coefficient of K=25 and incorporates the same early suppression and quick response characteristics of Listed K14 ESFR sprinklers, but with a lower operating pressure. In some instances, the lower operating pressure may also eliminate the need for a fire pump. This sprinkler is fitted with nominal one-inch inlet threads as compared to nominal 3/4-inch inlet threads on large-orifice and K14 ESFR-type sprinklers.

The ESFR-25 sprinkler was subjected to an exhaustive series of eight large-scale fire tests in the Large-Scale Fire Test facility at UL's testing station in Northbrook, Ill. Storage heights ranged from 20 to 40 feet; ceiling heights from 30 to 45 feet; and clearances between the sprinkler and the top of the commodity varied from 5 to 15 feet. The ESFR-25 sprinkler is the first to be tested and Listed by UL for the protection of rack storage of Group A plastics up to 40 feet high in a 45-foot high building. The fire test results are presented below.

In preparation for each fire test, ESFR-25 sprinklers were installed on a 10 by 10-foot spacing with the sprinkler deflectors positioned 18 inches below the ceiling. The 18-inch distance was chosen to help facilitate the installation of sprinkler system piping below ceiling supports and obstructions. Three different ignition locations were selected for these tests - one ignition directly under one sprinkler, another with the ignition positioned between two sprinklers and a third with the ignition centered between four sprinklers.

Standard Group A plastic commodity was used as the test fuel in each fire test. This commodity consists of single-wall corrugated fiberboard cartons measuring 21 inches in width, length and height, containing 125 crystalline, 16-ounce polystyrene plastic cups arranged in five layers of 25. Eight cartons of cups are then placed in a two-by-two array on a 42-by-42 by five-inch high two-way hardwood pallet. The number of plastic cups required for each large-scale fire test ranged from 128,000 for the 20-foot high to 256,000 for the 40-foot high test arrangement.

ESFR-25 Large-Scale Fire Test Results 

The double row racks in the main storage array were provided with six-inch longitudinal and transverse flue spaces. For ignition, four standard cellulose/cotton igniters were positioned in the center six-inch transverse flue space, in between the upright rack supports. These upright rack supports interfere with the development of the fire plume as the hot gases rise up toward the ceiling to activate the sprinklers. Then, once a sprinkler operates, the rack uprights obstruct the water discharged from the ceiling-mounted sprinklers into the flue space. A sufficient amount of water must penetrate the flue spaces, suppress the fire, and prevent it from spreading laterally and horizontally throughout the storage array.

UL anticipates that these new fire suppression sprinklers will be installed in many high-risk storage locations to improve the level of protection provided while eliminating the need for in-rack sprinklers.

The Listing information for the Grinnell ESFR-25 sprinkler is described in the category Early Suppression Fast Response Sprinklers (VNWH) in the Fire Protection Equipment Directory. For more information, contact George Laverick in Northbrook, Ill., at +1-847-272-8800, ext. 42665; or fax him at +1-847-272-2020.