• <br />• <br />• <br />NFPA 14 requires that riser isolation valves <br />separately control the feed to each standpipe <br />(Figure 4.11). Sequential valves are not acceptable <br />where a single valve in the bulk main can <br />shut off more than one downstream riser. For <br />risers in stairways, the riser isolation valves should <br />be within the fire-rated stair enclosure to protect <br />firefighters who may need to operate them. <br />Previous editions of NFPA 14 required designers <br />to place the riser isolation valves at the bottom of <br />the risers to make them quickly accessible to fire- <br />fighters. Fire departments may still prefer that <br />these valves be located on the level that they use <br />for their primary entry. If the bulk feed main is <br />located on a different level it could be piped up or <br />down to the fire department entry level, where the <br />isolation valve would be placed for that particular <br />riser (Figure 4.12). <br />Considerations - Standpipe Isolation Valves <br />■ Provide a separate valve "on each riser for <br />independent control. <br />■ Locate valves for risers in stairs within the <br />stair enclosure. <br />Locate valves on fire department entry level <br />(Fig. 4.12) The feed for this standpipe <br />was on a level above the fire department <br />entry. The supply pipe was fed down (on <br />the left) to the entry level, where the iso- <br />lation valve was located. Then, the pipe <br />was routed back upwards (on the right) to <br />feed the standpipe riser. <br />40 <br />OTHER DESIGN ISSUES; <br />Standpipes should be installed as the construction <br />of a building progresses. These can be temporary <br />or permanent. Both the IFC and NFPA 241, <br />Standard for Safeguarding Construction, Alteration, <br />and Demolition Operations, contain requirements <br />for standpipes during construction. Design docu- <br />ments should indicate the applicable requirements. <br />A marked, accessible fire department connection <br />(see the section, Marking, page 47) can suffice as a <br />water supply until building construction progress- <br />es to the point at which the water supply system <br />and fire department pumpers can no longer pro- <br />vide adequate pressure to the system. At this point, <br />a temporary or permanent fire pump also becomes <br />necessary. <br />In climates subject to freezing temperatures, it <br />is vital that standpipes in unheated areas be dry <br />type systems. Heat tracing and insulation are inef- <br />fective protection for dry fire protection systems <br />because water is not normally flowing through the <br />piping. <br />Large dry systems deserve special considera- <br />tions. As the size of a dry system increases, the <br />time required to deliver water to the remote hose <br />connection increases. This is due to the increased <br />pipe volume that must be filled. This can be miti- <br />gated by subdividing the system into smaller inde- <br />pendent systems, or zones. The disadvantage is <br />that fire department inlet connections to dry systems <br />cannot be interconnected (Figure 4.13). See the sec- <br />tion, Marking, page 47, for specific recommenda- <br />tions regarding zone indicator signs or diagrams. <br />Considerations - Other Design Issues <br />■ Specify temporary standpipes during con- <br />struction. <br />■ Specify installation of the pump when height <br />exceeds fire department capability. <br />■ Design to mitigate long fill times for dry <br />standpipe systems. <br />os ll'1, <br />Occupational Safety and <br />Health Administration <br />(Fig. 4.13) FDCs for <br />separate manual dry <br />standpipe systems <br />in a large parking <br />garage. <br />156 <br />