Fusible alloy/Sprinkler bulb ESFR sprinkler heads

Background – History

In the 1980s, early suppression, fast response (ESFR) sprinkler systems were developed as an alternative to in-rack systems. They were designed to actually suppress or extinguish the fire, while conventional sprinklers can only control fires, therefore eliminating the need for extinguishment by firefighters.
How do they work? ESFR sprinklers are designed to release 2-3 times the amount of water of conventional sprinkler heads and to emit larger droplets of water, which in turn have a greater momentum than droplets emitted from conventional heads. As a result, more water and a greater share of the water reaches the fire allowing the flames to be extinguished.

Application

In general, ESFR systems can be used in warehouses with storage that do not exceed 40 feet in overall height, and with a ceiling height of less than 45 feet. And there are sprinkler system protection schemes that will allow storage above those heights. These may include in-rack sprinklers or a combination of ESFR with in-rack sprinklers.
ESFR systems are designed to protect a wide array of commodities. This provides more flexibility in warehouse operations when compared to control mode (conventional) sprinkler systems, which are designed to protect only the commodities that were stored at the time of system installation. If the storage situation requires in-rack sprinklers to be installed to the existing control mode systems of a warehouse building, often building owners prefer to change over to ESFR, simply because then there is no need to worry about damaging in-rack sprinkler heads during normal storage operations. Additionally, in-rack sprinklers have to be removed and sometimes replaced with each new tenant, since the tenants own the racks. Therefore, converting to an ESFR system is at times more cost-effective in the long run.