INLETS <br />Most standards do not specify the number of inlets <br />required on each FDC. NFPA 13 does say that a sin- <br />gle inlet is acceptable for FDCs feeding pipe that is <br />3 inches or smaller. However, no requirements are <br />identified beyond that. Many FDCs have dual <br />inlets; these are often referred to as "siamese" con- <br />nections. One rule of. thumb is to provide one inlet <br />for each 250 gallons per minute (gpm) of system <br />demand, rounded up to the next highest increment <br />of 250 gpm. For example, if the system demand is <br />700 gpm, the designer would specify three inlets. <br />Likewise, a system with a demand of 800 gpm <br />would need four inlets (Figure 5.3). <br />To permit the connection of hoselines, the inlet <br />size and type (threaded or quick-connect) must <br />match the type used by the particular fire depart- <br />ment. In jurisdictions.where the fire service uses <br />threaded hose couplings, FDCs include one or <br />more 2% inch-size hose inlets (Figure 5.2). The <br />thread type will usually be NH Type (American <br />National Fire Hose Connection Screw Thread). To <br />facilitate the connection of the externally threaded <br />(male) end of fire hose lines, threaded inlets <br />should be the swiveling, internally threaded <br />(female) type. The non-threaded connections will <br />usually be 4 or 5 inches in size (Figure 5.4). <br />NFPA 1963, the Standard for Fire Hose Connect- <br />ions, sets out specific detailed requirements for <br />both threaded and non-threaded (quick-connect) <br />hose connections. <br />The inlets are ordinarily required to be provided <br />with threaded plugs or breakaway-style caps. It is <br />important for the designer to specify these to mini- <br />mize the chance of an inlet being obstructed by <br />trash or debris. If a firefighter notices an inlet <br />blocked by debris, connection of hose lines will be <br />delayed while he or she attempts to clear it. If the <br />debris cannot be removed, that particular inlet or <br />the entire FDC may be rendered unusable. Un- <br />noticed debris could block most of the flow to a fire <br />hose connection or a significant section of a <br />sprinkler system. Even worse, a firefighter could be <br />operating a hose line inside and suddenly have the <br />blockage clog the nozzle. <br />Designers may specify lockable inlet caps for <br />security. Designers should obtain permission from <br />the fire department to use these caps, unless the <br />department requires their use. In addition, <br />designers should specify that building owners <br />provide tools or keys for unlocking these caps to <br />the fire department. <br />Considerations - FDC Inlets <br />■ Match type of connection and thread type to <br />the fire department's hose. <br />■ Provide caps or plugs for each inlet. <br />■ Security caps: Obtain permission if optional <br />and specify that building owners give keys <br />to the fire department. <br />■ Large capacity systems should have one 2'/2 <br />inch inlet for each 250 gpm of system <br />demand, unless a large capacity, quick- <br />connect FDC is used. <br />I <br />I <br />I <br />FIRE SERVICE FEATURES OF BUILDIMGS'AND FIRE PROTECTION &Y.STEMS 43 <br />159 <br />