Generally speaking brass extension nipples may be used to install/lower/position fire sprinkler heads, however, in some cases, their friction loss must be included in the design hydraulic calculations, check with your edition of NFPA 13 and your AHJ.
Below is photographed a fractured brass nipple, leak occurred after sprinkler head was installed. CPVC assembly is also shown:
Close up photo of the fractured brass extension nipple follows. Photograph taken through a hand held magnifying glass. Failure likely occurred as a result of excessive torque loads applied to fire sprinkler head during installation:
I've inspected a site recently in Australia with high hazard storage sprinklers, designed and hydraulically calculated to AS2118.1-1999 and FM DS 02-00.
ReplyDelete6 of 50mm runs on the gridded system, incorporating a main and slave main, have been installed differently to the others which are installed as per the design.
The 50mm gridded pipe runs are designed so that they raise the attached upright k22.4 (metric) ELO sprinkler to within 300mm of the ceiling- no issue there.
The variation is with the 6 pipe runs which weren't raised to within 300mm and instead incorporated cut and screwed 20mm or 3/4" sprigs using galvanised piping and gal mal sockets extending 150-200mm from the fabricated sprinkler pap sockets. This was used over approximately 300m2 area of the warehouse which is protecting, in part, high piled storage incorporating in-rack sprinklers.
The question is, are these 20mm sprigs permitted for use in High Hazard systems (a) without hydraulic calculation or (b) provided they are hydraulically calculated or do they breach the minimum 1" piping requirements specified in FM DS 02-00 and therefore need to be hydraulically calculated using at least the minimum pipe sizing specified?