Dousing the Flames: Fire Issues Move to the Front Burner, Part II

Aug 01, 2007 11:05 PM  By

This is the second in a two-part series. This week, we’ll address fire protection issues. Last week we discussed what causes fire in the DC; to read that story, click here

Sprinkler equipment has undergone an evolution in the last decade or longer, especially in terms of specialization. A wide variety of sprinklers and several types of piping can today be specified for the application being protected in a warehouse.

“Most warehouses today are equipped with early suppression/fast response (ESFR) sprinkler technology, which was developed for the purpose of eliminating in-rack sprinklers,” Musur explains. “Not only will they control a fire, but they also have the capability to suppress it as well.”

Musur notes that the ESFR sprinklers are designed for fast, vertical growing fires. “In a warehouse the fire typically travels vertically through the racks,” he explains. “It doesn’t spread out like a pool fire for liquids. ESFR is definitely best for rack storage warehouse layouts, but not for a pool fire,” he asserts.

In a warehouse the fire typically travels vertically through the racks.” Steve Musur Harrington explains that the ESFR sprinklers work well in test facilities under ideal conditions. However, he also cautions about storage practices that might “unknowingly defeat” or limit the effectiveness of ESFR sprinkler systems.

“One of the ways these systems are being defeated is by not properly managing the flue spaces in the racks,” he maintains. For example, in a six-tier double row rack layout, placing and picking pallets with a high-mast lift truck with an operator at ground level is “pretty much a blind operation.”

Harrington explains: What’s very common is that the top two levels of pallets get pushed together in the center, which blocks the flue. However, the lower tiers, where there is better visibility are often neater and usually have an established open area or flue space. “That’s the worse thing that can happen as a very strong fire forms in that center flue and in that air space, which is then blocked at the top of the ‘vertical chimney,’” he explains. “This delays the operation of the ESFR sprinklers because the heat of the fire is effectively stopped from rising to the ceiling. But when the heat finally does get to the ceiling and the ESFR sprinklers do operate, the same blockage then stops the water from getting to the fire itself.”

Harrington acknowledges that the “ESFR system has been a great marketing success and is installed in almost every warehouse, but we have not been as successful in getting the knowledge into the hands of the people who operate these warehouses how easily these systems can be defeated.”

In many warehouses, mezzanines are constructed to take advantage of the cube and to gain additional floor space. Musur advises when building a mezzanine or similar structure there is the requirement to provide a sprinkler system underneath the mezzanine, just like it’s a second ceiling.

“Provide the protection underneath the mezzanine commensurate with the activity that’s taking place whether storage or some value-added function as is now common in many warehouse locations,” he explains. He also points out that “anytime there is an obstruction wider than four-feet in width, such as an air conditioning or heating duct, or a cable tray, fire protection must be provided underneath the obstruction.”

“Where ESFR sprinklers are present,” says Harrington, “this width is reduced from four feet to two feet.” For example, certain conveyor systems less than four feet wide will require sprinkler protection beneath them in warehouses protected by ESFR sprinklers.

The warehouse manager, says Harrington, “should be in a position to ask certain leading questions of others in the organization that will enhance his/her knowledge of what is being brought into the warehouse that may have an impact on the safety and protection of not only the warehouse staff but also of the facility itself.” For example, ask: · “If we’re going to make this change have we run it by our risk management department, and what was their opinion?” ·“Have we sought an opinion from our insurance carrier, and what was their advice?” ·“Have we consulted with our local fire marshal, and what did he say?”

As an advisory for warehouse management personnel, Harrington cautions about sprinkler inspections that are conducted by outside contractors. “Most large facilities that have sprinklers hire a sprinkler contractor to perform periodic inspections and maintenance work,” he explains. The work is often done in accordance with NFPA 25 (“Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems”), which in many jurisdictions is required by law.

The perception is that the fire protection issue has been outsourced and taken care of, and that when the work is completed a report will be issued. The contractor, according to Harrington, only attests that the sprinkler is operational. “The contractor is inspecting the pipes, whether the hangers are intact, and whether there are any obstructions,” he explains. “They’re not looking at what is being stored underneath, where it might have come from, and how it will affect the sprinkler’s performance.”

What’s more, “The contractor is not certifying that the sprinkler system can handle the hazard,” he notes. “NFPA 25 exempts the contractor from having to consider the hazard and any changes that may have been made in the hazard since the last inspection.” This presents an issue that often leads to a misunderstanding of where the responsibility lies for protecting the contents in the warehouse.

Musur explains that the major insurance companies have loss-control or risk-management departments often staffed with fire protection engineers knowledgeable in warehouse fire safety requirements and regulations. “Invite that individual to your facility, have him look around and provide you with an assessment specific to your facility,” he says. Musur, also a fire protection engineer, adds, “When doing an assessment for underwriting purposes there are three main components we consider to determine what the fire protection needs must be.” They are: What is the commodity being stored? How high is it being stored? How is it being stored?

Another source for inspections, independent of sprinkler manufacturers or insurance companies,is the Society of Fire Protection Engineers (Bethesda, MD; www.sfpe.org). The organization will provide names of members in any geographic area worldwide who are capable of providing the service required.

The message for warehouse management is that fire prevention and protection issues are not the sole responsibility of the company’s facilities department. Instead, DCs need to become conversant and knowledgeable about the key factors for fire safe operations.

This article originally appeared in the July issue of the Warehousing and Education Research Council newsletter. For more information, visit www.werc.org.