Keep fire service considerations in mind
June 12, 2013
Do you wonder why fire sprinkler and standpipe system features are different from other plumbing systems? Many of the reasons are based on how the fire service uses or interacts with these features.
One goal of the Society of Fire Protection Engineers’ Fire Service Committee is to bridge the gap between the design community and the fire service – to help both groups better meet their responsibilities. Let’s look at some fire service-related features of sprinkler and standpipe systems. Consider this general knowledge to be used in addition to, rather than instead of, a particular jurisdiction’s mandatory codes and other requirements.
Fire service challenges
Why does the fire service deserve special treatment? Imagine awaking in the middle of the night, dressing and driving through all types of weather conditions within a minute or so. Soon, you are facing a fast-moving fire in an occupied building, forcing you to haul hose, ladders and other heavy equipment without wasting any time. Your boss must make critical decisions with a limited amount of information on the fire, the smoke it is producing and the occupants it is threatening.
This is a work environment foreign to those outside the emergency services. Actions and decisions made early in an incident with the limited available information can affect the course of an entire incident. These actions and decisions often rely on dependable fire-protection systems. Therefore, proper design and installation of these systems also can affect the course of an incident.
When sprinkler systems are out of service or not functioning properly, fire can spread unimpeded. When standpipe systems are not functioning properly, firefighting operations will be severely impacted. You only need to look back to 1991 in Philadelphia where three firefighters were killed at Meridian Plaza or 2007 in New York City where two firefighters were killed in the Deutsche Bank Building. Problems with the standpipes were listed as key factors in both incidents.
The basic need for a standpipe system in large or tall buildings is simple: To save time when inordinately long hose lengths would be necessary to reach a fire. Beyond a certain height, firefighters have no choice but to fight a fire from the inside.
There have been several code changes over the years to address changes in fire-service tactics and equipment. In particular, smaller hose diameters and fog, or combination nozzles, require higher pressure. Remember to coordinate the standpipe system design with the fire service – the firefighting forces as well as the code enforcement officials.
You may encounter a reluctance to allow the use of pressure-regulating devices on fire hose valves. Problems with these devices were documented in the Meridian Plaza incident. Of course, fewer devices subject to failure (regardless of how unlikely a failure is) will increase the overall reliability of systems. These devices have two other inherent limitations: Pressure cannot be increased beyond their design setting if needed due to the circumstances encountered, and water cannot be fed upstream through them as a backup to the fire department connection.
Where pressure-regulating devices must be used, it is important to ensure their correct design and installation. You also may see an ordinary fire hose valve next to one with a pressure-regulating device on the ground floor — as a backup to the fire department connection.
During interior firefighting operations, fire-rated stairways are safe havens for firefighters as well as occupants. Firefighters are taught to follow a hose line back to its source if they must exit. When operating from stairway standpipes, the source is within the stairway. Many fire departments have a standard operating procedure that calls for hose lines to be supplied by fire hose valves below the fire floor. This has resulted in a preference in some jurisdictions for FHVs to be located on intermediate stair landings rather than the main landings at the same level as the occupied floors. This way, less hose is needed to reach the first FHV below each floor. In addition, on intermediate landings FHVs will not be obstructed by doors.
In some cases, due to the hose lengths required, remote FHVs will be located outside stairs. In these cases, some protection can be afforded by locating them in corridors. It would be very unusual for firefighters to use FHVs located within a tenant space or in a remote corner, simply because fire attack should begin from a position of relative safety where egress is possible.
In parking garages, consideration should be given to locating FHVs where they are not between vehicles and where they are protected from vehicle impact.
Exterior FHVs are used for building spaces or tenants with exterior-only access. This is most critical when fire apparatus access is not provided near these spaces (e.g., retail spaces along a promenade or boardwalk).
Domestic plumbing systems in multistory buildings usually are arranged vertically with lavatories, kitchens and bathrooms located above the ones on the floor below. Did you know sprinkler systems usually are piped in horizontal zones? That way, when a sprinkler head is activated by a fire, the sprinkler flow switch connected to the fire alarm system will identify the floor where the fire is. The fire service can then proceed to the correct floor without delay.
Sprinkler or standpipe control valves may need to be quickly accessed during an emergency operation. A valve may need to be turned on, for example, if it was inadvertently left off or it was intentionally shut off by a vandal or arsonist. A valve may need to be turned off quickly to isolate a section of a system that failed. Standpipe systems have isolation valves to segregate each vertical riser for just this situation. For these reasons, valves must be located in quickly accessible locations, even if this means extra piping.
A good location for a main building shutoff valve is outside the building. Locating it away from doors, windows or other openings will keep it accessible if fire is issuing from the opening. The next best location for a main building shutoff valve is in a room with exterior access and the door marked.
The best location for interior zone valves is in a fire-rated stair. How about when you have no choice but to place a valve in an interior room? Label the door. Valves located above a ceiling are difficult to find and are less accessible. If the ceiling is a suspended grid-type, be sure signs are mounted to the grid and not the ceiling tiles, which can easily be relocated.
Access issues arise with fire pumps as well. The preferable location is in a separate building that cannot be affected by a fire in the building containing the system fed by the pump. The next best location is in a room with an exterior door. Access to interior rooms can be improved with a fire-rated corridor connecting it to the exterior, although any other rooms opening into that corridor are a potential exposure.
Fire department connections
You might wonder why a fire department connection is needed when a sprinkler or standpipe system is fed by an automatic water supply. These systems are designed to automatically feed a limited number of sprinkler heads or FHVs. If additional flow is required or there is a problem with the water supply, the FDC allows the fire department to supplement the volume of water and boost the pressure. In some buildings, such as high-rises, two fully redundant FDCs may be provided.
Multiple FDCs also may be in place to feed multiple sprinkler systems or both sprinkler and standpipe systems. You might encounter a preference that these systems be interconnected such that fire hoses feeding one FDC will supply all systems. The downside of this is one failure in the interconnecting piping will take all FDCs out of service. As a result, you also may encounter jurisdictions that prefer FDCs not be interconnected.
Quick access to FDCs obviously will streamline operations. Several considerations may come into play: location, position, proximity to openings, obstructions, access surface/slope/width and marking. Signage can provide important information to firefighters, such as system coverage (full or partial), inlet pressure, and depth and length for underground systems.
Since the FDC must be supplied with water, a nearby fire hydrant or other water source will facilitate operations. A maximum distance to the water supply may be preferred to preclude long hose lays or enable the use of preconnected hose lines from fire apparatus. In some cases, a freestanding FDC may be located away from the building to get it close enough to a water supply or to remove it from the potential collapse zone.
Finally, tampering with FDCs is a very real issue. Any foreign material placed into an FDC may clog a downstream sprinkler or nozzle. This can make for a very bad day for firefighters performing an interior attack. Caps or plugs on FDC inlets minimize this problem. However, they are easily defeated. Lockable plugs or caps are available to make tampering more difficult.
Increased building hazards
During construction or demolition, buildings often contain more hazards and have a higher fire frequency than finished buildings. Several temporary features often are employed during the construction or demolition phases. At least one temporary standpipe should be in place once construction reaches a certain level and should be raised as the construction proceeds. The temporary FDC for this standpipe should be well-marked and accessible around construction materials. It is important to maintain the standpipe in service as it is extended during construction or shortened during demolition. An out-of-service standpipe system was a major factor in the Deutsche Bank Building incident.
When fire protection systems near completion, it is time to help the fire service with its preincident planning. The more familiar firefighters are with these systems, the more efficient they can be during an emergency. Invite the fire service to learn about the sprinkler and standpipe systems, including the location of control valves and fire pumps, before the building is occupied. I am referring here again to the firefighting forces in addition to the code enforcement personnel who may have a role in approving systems.
Mat Chibbaro is a fire protection engineer with the OHSA national office in Washington and is the outreach group leader for the Society of Fire Protection Engineers’ Fire Service Committee. He is a licensed professional engineer in fire protection in California and Maryland. His views in this article do not purport to reflect official views of OSHA or the U.S. Department of Labor.