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High-rise Office Building Fire One Meridian Plaza Philadelphia, Pennsylvania


Perhaps the most striking lesson to be learned from the One Meridian Plaza high-rise fire is what can happen when everything goes wrong. Major failures occurred in nearly all fire protection systems. Each of these failures helped produce a disaster. The responsibility for allowing these circumstances to transpire can be widely shared, even by those not directly associated with the events on and before February 23, 1991.

To prevent another disaster like One Meridian Plaza requires learning the lessons it can provide. The consequences of this incident are already being felt throughout the fire protection community. Major code changes have already been enacted in Philadelphia (see Appendix G) and new proposals are under consideration by the model code organizations. These changes may eventually reduce the likelihood of such a disaster in many communities.

1.Automatic sprinklers should be the standard level of protection in high-rise buildings.

The property conservation and life safety record of sprinklers is exemplary, particularly in high-rise buildings. While other fire protection features have demonstrated their effectiveness over time in limiting losses to life and property, automatic sprinklers have proven to provide superior protection and the highest reliability. Buildings in some of the nation’s largest cities, designed and built around effective compartmentation, have demonstrated varying success at containing fires, but their effectiveness is often comprised by inadequate design or installation and may not be effectively maintained for the life of the building. Even with effective compartmentation, a significant fire may endanger occupants and require a major commitment of fire suppression personnel and equipment. Retrofitting of automatic sprinklers in existing buildings has proven effective in taking the place of other systems that have been found to be inadequate. 2. Requirements for the installation of automatic sprinklers are justified bv concerns about firefighter safetv and public protection effectiveness. as well as traditional measures such as life safety and property conservation.

The property protection value of sprinklers was recognized long before life safety became a popular justification for installing fire protection. Life safety has become the primary concern in recent times, justifying the installation of automatic sprinklers in high-rise buildings. The value of sprinklers as a means of protecting firefighters has rarely been discussed.

Members of the fire service should promote automatic fire sprinklers if for no other reason than to protect themselves. Requiring the installation and maintenance of built-in fire protection should become a life safety issue for firefighters.8 The opposition to retrofit protection has consistently cited cost concerns. Communities need to be made aware that the costs they defer may be paid by firefighters in terms of their safety. This is above and beyond the potential loss to citizens and businesses that is usually considered.

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3. Code assumptions about fire department standpipe tactics moved invalid.

One of the principal code assumptions affecting fire department operations at One Meridian Plaza concerned the installation of standpipe pressure reducing valves. The rationale for PRVs is the concern that firefighters would be exposed to dangerous operating pressures and forces

Firefighters at One Meridian Plaza had great difficulty determining how to improve flow and pressure from hose outlets during the fire. Even if firefighters could have closely examined the valves, with good light and under less stressful conditions, it is unlikely that they would have been able to readjust the valves. Numerical indicators on the valve stems represented an index for adjustment not the actual discharge pressure. (This may have confused the technicians responsible for installing and maintaining the valves. Investigators found valves set at “20” and “80” on the index markings. To achieve 65 psi would have required a setting from 88 to 91 on the index. A setting of 150 to 158 was necessary to produce the maximum allowable 100 psi.)

Pressure regulating devices come in three different types:

Pressure restricting devices which reduce pressure under flowing conditions by reducing the cross-sectional area of the hose outlet.

Pressure control valves are pilot-operated devices which use water pressure within the system to modulate the position of a spring-loaded diaphragm within the valve to reduce downstream pressure under flowing and non-flowing conditions.

Pressure reducing valves use a spring-loaded valve assembly to modulate the position of the valve disc in the waterway to reduce the downstream pressure under flowing and non-flowing conditions.

Further differentiation within each of these types results from differences in manufacturer specifications. (Details are provided in the Philadelphia Fire Department fact sheet on pressure regulating devices in Appendix G.) Some devices are field adjustable, some are not. Some can be removed to permit full, unrestricted flow, others cannot.

if they connected hose lines to outlets near the base of standpipe risers of substantial height, particularly those supplied by stationary fire pumps. For example, in a 275 foot high standpipe zone (the highest permitted using standard pipe and fittings), a pressure of 184 psi is required at the base of the riser to overcome elevation and produce the minimum required outlet pressure of 65 psi at the top of the riser. At this pressure, a standard 2 1/2-inch fire hose fitted with a 1 1/8-inch straight bore nozzle would produce a back pressure (reaction force) in excess of 500 pounds. This is a well-founded concern; however, it is built upon the assumption that fire departments use 2 1/2-inch attack lines and straight bore nozzles to attack fires from standpipes. Most fire departments today use 1 3/4-inch and 2-inch hose with fog nozzles for interior attack. These appliances require substantially greater working pressures to achieve effective hose streams.

In the aftermath of this incident, the NFPA Technical Committee on Standpipes has proposed a complete revision of NFPA 149 to more closely reflect current fire department operating practices. Section 5-7 of the proposed standard requires a minimum residual pressure of 150 psi at the required flow rate from the topmost 2 1/2-inch hose outlet and 65 psi at the topmost 1 1/2-inch outlet (presumably for occupant use). Minimum flow rates of 500 gpm for the first standpipe and 250 gpm for each additional standpipe remain consistent with past editions of the standard. The proposed new requirements limit the installation of pressure regulating devices to situations where static pressures at hose outlets exceed 100 psi for occupant use hose or 175 psi for fire department use hose. This will provide substantially greater flow and pressure margins for fire department operations. These requirements are intended to apply to new installations and are not retroactive.

4. The requirements and procedures for design. installation. inspection, testing. and maintenance of standpipes and oressure reducing valves must be examined carefully.

The proposed revision of NFPA 14 (1993) and a new NFPA document, NFPA 25, Standard for the Installation, Testing, and Maintenance of Water-Based Fire Protection Systems (1992), address many of the concerns arising from this fire regarding installation and adjustment of pressure reducing valves. NFPA 14 requires acceptance tests to verify proper installation and adjustment of these devices. NFPA 25 requires flow tests at five year intervals to verify proper installation and adjustment.

The report of the Technical Committee on Standpipes appears in the NFPA I992 Fall Meeting Technical Committee Reports, pp. 331-367.

Neither of these standards proposes changes in the performance standards for the design of pressure reducing valves.

Standard performance criteria for the design and operation of each type of valve should be adopted to encourage user-friendly designs that will permit firefighters to achieve higher pressure and flow rates without interrupting firefighting operations. The operation and adjustment of valves should be easy to identify and clearly understandable by inspection and maintenance personnel without reliance on detailed operating or maintenance instructions.

It is extremely important to have all systems and devices thoroughly inspected and tested at the time of installation and retested on a regular basis. Fire suppression companies that respond to a building should be familiar with equipment that is installed in its fire protection systems and confident that it will perform properly when needed.

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