What Are They?
The use of Early Suppression Fast Response (ESFR) sprinkler systems is becoming more prevalent in the protection of warehouse storage occupancies. But what are ESFR sprinklers and what is their benefit? In answering these questions, we will first look at types of systems that are used to protect warehouse occupancies.
Types of Sprinkler Systems – Warehouse Occupancies
There are two basic types of sprinkler systems used to protect storage hazards. These systems are classed by the type of sprinkler head which is:
- Control Mode sprinkler heads, and
- ESFR sprinkler heads.
Control Mode Systems
Control mode sprinkler systems are designed to control a fire until its original fuel source is depleted or until fire fighting activities can commence. A fire is controlled by cooling the ceiling level air temperatures, reducing the fire’s rate of heat release, and pre-wetting adjacent combustibles.
ESFR sprinkler systems are designed to extinguish as opposed to control a fire. Extinguishment is accomplished by discharging increased water flows (when compared to control mode systems) directly to the fire. This increased flow penetrates the fire plume (rising hot gases usually accompanied by smoke) and attacks the fire?s fuel source, thus reducing the heat release rate of the fire until it is extinguished.
Control Mode Installations
Prior to the introduction of ESFR sprinklers in the late 1980?s, all warehouse storage facilities were protected by control mode sprinklers. Furthermore, storing commodities in storage racks typically required the installation of in-rack sprinkler systems.
In-rack sprinkler systems are a cause of concern to many warehouse operators in that they add to the cost of the sprinkler installation and require modification if the racking layout is changed. However, the most important concern is that of mechanical damage caused by the constant movement of goods in and out of the racks by forklift trucks.
For most applications, ESFR systems eliminate the need to install an in-rack sprinkler system.
Also, ESFR systems are typically designed to protect a wide array of commodities ranging from steel to plastic (control mode systems are often designed to protect only the commodities that were stored at the time of system installation). This grants the warehouse operator greater flexibility when considering future storage operations or leasing opportunities.
ESFR system material costs tend to cost more that control mode systems (larger pipe sizes, more expensive sprinkler heads). Also, in most cases an ESFR system will require the installation of a fire pump which is not always required for a control mode system. However, an ESFR system will offer savings, as in most cases, in-rack sprinkler systems are not required.
ESFR System Considerations
The benefits of ESFR systems are listed above, however there are certain considerations that must
be addressed prior to using an ESFR system. These considerations include:
- Storage Heights – maximum permitted storage height of 40 ft.
- Building Heights – maximum permitted building height of 45 ft.
- Rack Shelving – solid rack shelving is not permitted
- Fire Pump – large discharge rates and high system operating pressures will require
the installation of a fire pump, and
- Obstructions – ESFR sprinkler heads are more sensitive to obstructions (lighting, pipe, structural members, duct, etc.) that will require greater system design coordination
By Richard Weldon – P.Eng, LEED AP and Don Casey