Welcome to Commercial Inspection Tips, a monthly ASHI Reporter feature written by a leading commercial inspection training firm, Carson Dunlop Weldon & Associates. Each month, we feature a new article that provides useful technical and business information on commercial building inspections. Our goal is to stimulate your interest in diversifying into the field of commercial building inspections as a way to expand and grow your business.
Fire suppression systems are commonplace in commercial buildings. Because they must meet different needs and often satisfy specific regulations, they are as varied as the buildings they are found in. What follows is a brief introduction to one type of system.
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 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.
The design of control mode systems acknowledges that a certain number of sprinkler heads will operate directly above and around the fire (fire area). In operation, the sprinklers located directly above the fire reduce the fire’s heat release rate and cool the ceiling-level air temperature. Cooling the ceiling-level air temperatures works to prevent the operation of sprinklers beyond the fire area while protecting against structural damage that could result from high ceiling-level air temperatures.
Sprinklers operating in the remainder of the fire area also cool the ceiling-level air temperatures while pre-wetting
adjacent combustibles. Pre-wetting adjacent combustibles helps to prevent the spread of fire beyond the fire’s origin.
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 1980s, 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 for 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 materials tend to cost more than 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.
As discussed, the use of ESFR systems has certain restrictions, namely building and storage height and sprinkler head obstructions that require more attention to be paid to coordination with other trades. That said, considering the flexibility granted to future storage uses and in most cases, eliminating the occurrence of in-rack system discharge onto stored commodities, it is not surprising that more warehouse operators are turning almost exclusively to the use of ESFR sprinkler systems.
Article prepared by Richard Weldon, P.Eng. of Carson Dunlop Weldon & Associates (CDW) and Don Casey of Randal Brown & Associates Ltd.(RBAL). CDW is a consulting engineering firm that specializes in Property Condition Assessments. RBAL provides fire protection, life safety and building code consulting engineering services across Canada and the United States.
Carson Dunlop Weldon & Associates is a leading provider of commercial inspections and commercial inspection training, author of the Technical Reference Guide and the CommQuotTM Commercial Fee Quoting and Proposal Writing System. This article and accompanying diagrams have been taken from a new, not-yet-released Commercial Building Inspection Training Module written by Carson Dunlop Weldon & Associates Ltd. Visit www.cdwengineering.com.