Firefighters use self-contained breathing apparatus (SCBA) for interior fire fighting. SCBA air is supplied by cylinders (often referred to as “bottles”) that have a limited amount of air. When depleted, these air cylinders need to be refilled or replaced with full ones. Some fire service organizations have specialized vehicles that contain systems known as “cascade systems” that refill breathing air cylinders at fire scenes.
A firefighter breathing air system is a system of piping within a tall building or a sprawling structure that enables firefighters to refill their breathing apparatus cylinders at remote interior locations. These systems are essentially air standpipe systems. A few jurisdictions in the U.S. require such systems for high-rise buildings, or for long (i.e., over 300 feet) underground tunnels (both pedestrian and transportation).
Without such systems, firefighters must carry additional breathing air cylinders to a staging area, and others must transport cylinders back and forth from a supply point outside. Permanently installed breathing air systems make emergency operations safer and more efficient by eliminating the need to carry extra cylinders, reducing the time and personnel needed for logistical support. However, proper function is dependent upon careful, thorough design, as well as regular maintenance.
A firefighter breathing air system consists of a piping distribution system that runs from a supply point to interior “fill stations” or “fill panels.” Fill panels contain short sections of hose with connections that fit firefighter’s air cylinders. Fill stations are larger enclosures in which cylinders are replenished within a blast fragmentation container using rigid fill connections. Both alternatives have the necessary valves, gauges, regulators, and locks to prevent tampering. Their mounting height should facilitate easy connection of cylinders.
A good location for fill points (panels or stations) is just outside enclosed, fire-rated stairs. Placement at every second or third level provides reasonable coverage. This distribution enables firefighters to locate fill points quickly and set up a replenishment operation in safe proximity to the fire. With fill points just outside the stairs, refill operations will not impede stairway traffic (whether firefighters or occupants). A sign within the stair enclosure, at each level with fill points, can indicate the location of fill points (for example: “Breathing Air Fill Panel, Out Door and 10 Feet to the Right.”). Fill points should only be located inside the stair enclosure after careful consideration by the fire department and if additional space is allocated for refilling operations. For tunnels, designers should locate fill points a reasonable spacing apart, perhaps 200 feet.
The supply to the distribution system will vary according to fire department capabilities and preferences. One approach is to provide one or more exterior fire department connection panels through which the fire department supplies air from a mobile air supply unit. Another is to provide fixed air storage cylinders within the building, and an exterior backup fill connection. The fixed storage components would be in a lockable, air conditioned, fire-rated room with emergency lighting and a pressure relief vent.
All fire department fill connection panels should be in weather-resistant, locked enclosures marked to indicate their use. Many of the design considerations for these connections are similar to those in Chapter 5 for sprinkler/standpipe connections. They should be located to make it possible for the fill lines on the air fill unit to reach the connection panel.
The designer should provide a fire lane or a road for the mobile air fill unit to access each fill connection. Some of the design considerations in the section, Fire Apparatus Access, on page 11, also apply, in particular the paragraphs on material, gates, barricades, security measures, and marking. The clear height and width would need to accommodate only the fill unit, unless it also serves as access for larger fire apparatus.
Reliability features are highly desirable on breathing air systems. The piping should stay pressurized and the system should include a low air pressure monitoring device. Air quality may be supervised with carbon monoxide and moisture monitors. The designer should specify an air quality analysis for the initial system acceptance as well as ongoing periodic testing. The designer should call for good installation practices, including keeping the piping free of oils, dirt, construction materials, or other contaminants.
For adequate protection throughout an incident, all components of the system should be separated from other portions of the building or tunnel by fire-rated construction. A rating equivalent to that required for stair enclosures is reasonable.
The performance of the entire system should be specified in terms of the number of air cylinders to be filled simultaneously at remote locations, the fill pressure, and the fill time. This will dictate the size of the distribution piping and any air storage cylinders. All components should be specified for use with breathing air, and marked to indicate their use.