Early Suppression Fast-Response (ESFR) sprinklers are now commonly referred to as Suppression Mode Sprinklers. This is due to the fact that they are designed to actually extinguish a fire rather than to just control a fire. Suppression Mode Sprinklers deliver a lot of water at a very high pressure. This allows the water to travel from these sprinklers all the way down to the fire area. This may not sound very difficult to do. However, water is absorbed by storage around the fire area, and some of the water evaporates due to the heat produced from the fire. Control mode sprinklers do not deliver enough water to be able to accomplish this. This is why in-rack sprinklers are typically needed for suppression mode sprinklers or ESFR sprinkler systems.
Many factors exist that would hinder Suppression Mode sprinklers or ESFR sprinkler systems from extinguishing a fire. Some of these factors can even lead to the sprinkler system not being able to get enough water to the fire where this fire burns out of control.
Suppression Mode (ESFR) Sprinklers are particularly susceptible to blocked flue spaces in rack storage arrangements. Flue spaces are openings within storage racks that have a clear line of sight from the floor to the ceiling. Flue spaces serve two functions. One function is to allow the fire to spread vertically. Since fires continue to spread horizontally until they can spread vertically, blocked flue spaces can increase the size of a fire. The quicker the fire spreads vertically, the quicker the ESFR sprinklers operate.
Flue spaces also provide a path for sprinkler water to reach a fire. If ESFR sprinkler water cannot reach the fire, then the sprinklers would not be able to extinguish nor control this fire. Adequate flue spaces will help to ensure that ESFR sprinkler water can reach the fire and help to limit the horizontal spread of the fire.
Something that also hinders water from reaching a fire is open-top containers. These are containers that are enclosed on the sides and bottom, but not on the top. An example of this would be a plastic shelf bins. These bins fill up with water, hindering the ESFR sprinklers from effectively suppressing a fire.
Additionally, Suppression Mode Sprinklers are highly susceptible to obstructions. These obstructions can be caused by: girders, joists, braces, plumbing, and electrical/communications wiring and conduit. Obstructions from girders, joists, and braces can typically be avoided with properly designing and positioning the sprinkler system. Plumbing, electrical, and communication wires are often installed after the sprinkler system. Installation of these items should be coordinated to ensure that they do not introduce sprinkler system obstructions. Also, changes are often made to these items long after the sprinkler system is installed. Care should be given to ensure that these changes do not cause new obstructions.
Another hurdle for Suppression Mode sprinklers is fans located at or near the ceiling. Building exhaust fans and large ceiling fans move large volumes of air. This may be desirable for both comfort on hot days and for removing smoke (from a fire) from the building. However, the heat produced by a fire needs to buildup at the ceiling to allow the sprinklers to operate as designed. If these fans expel heat too quickly, the operation of these sprinklers would be significantly delayed, causing the fire to grow too large for suppression by the sprinklers. Ceiling fans can also cause obstructions to the sprinklers.
Thus, items to watch in ESFR protected buildings are: flue spaces, open-top bins, changes at the ceiling, and fans at or near the ceiling.
If you would like further information regarding Suppression Mode sprinklers, please contact Risk Logic Inc.
Suppression-Mode Sprinkler Facts and Figures
This table was first presented in the August 2003 Technical Article. Some of the manufacturers have changed, so this table has been updated.
ESFR Sprinkler | Year Approved | Approximate Flow at 50 psi (3.5 bar) | Max Storage/Ceiling Height | Ceiling-to-Deflector Clearance | Manufacturers |
K 16.8 Upright | 2002 | 119 gpm (460 L/min) | 30 ft./35 ft. (9m/11m) | 14 in. (356mm) | |
K 22.4 Pendent | 2001 | 158 gpm (598 L/min) | 40 ft./45 ft. (12m/14m) | 18 in. (475mm) | Reliable |
K 14 Upright | 2001 | 100 gpm (379 L/min) | 30 ft./35 ft. (9m/11m) | 14 in (356mm) | Viking |
K 16.8 Pendent | 2000 | 119 gpm (460 L/min) | 35 ft./40 ft. (11m/12m) | 14 in (356mm) | Viking, Tyco |
K 25.2 Pendent | 1998 | 178 gpm (675 L/min) | 40 ft./45 ft. (12m/14m) | 18 in. (475mm) | Viking, Tyco |
K 14 Pendent | 1998 | 100 gpm (379 L/min) | 350 ft./40 ft. (11m/12m) | 14 in (356mm) | Kidde, Reliable, Tyco, Viking |
Risk Logic, Inc. can be of assistance to ensure ESFR Sprinkler Systems are installed properly, to avoid a major property loss.