Fire Sprinkler Installation Standards and Codes
Domain 2 is about which document governs and what the installation must physically look like before it is accepted: material and pipe standards, support and bracing, clearances, alarm and drain trim, flushing, and the hydrostatic test that releases the system for service. The exam expects you to know where NFPA 13 ends and NFPA 13R, 13D, 14, 20 and 24 begin.
Picking the right standard
NFPA 13 covers commercial, industrial and most residential occupancies above the 13R thresholds. NFPA 13R applies to residential occupancies up to and including four stories and 60 ft in height, and NFPA 13D to one- and two-family dwellings and townhouses. NFPA 14 is standpipes, NFPA 20 fire pumps, NFPA 24 underground mains and NFPA 25 the maintenance benchmark. A question that describes a five-story apartment building is testing whether you refuse to use 13R.
Installation rules that get tested
Pipe must maintain at least 1 in clearance from combustible construction. Sprinkler pipe is installed with eccentric reducers, drains at low points, and auxiliary drains on dry systems. The inspector's test connection must simulate the flow of a single sprinkler of the smallest orifice on the system and discharge to a visible location. Underground mains are flushed at a minimum of 10 ft/s before connection to the riser, and the waterflow switch must alarm on flow equivalent to one sprinkler.
Worked example
A system's maximum working pressure is 165 psi. Because that exceeds 150 psi, the hydrostatic test is conducted at 50 psi above working pressure - 215 psi - for two hours, and 215 psi governs over the 200 psi floor. Had working pressure been 120 psi, the test would have been 200 psi for two hours. Test pressure is calculated from working pressure, never assumed to be 200 psi.
Traps that cost marks
Testing before flushing the underground; using 200 psi on a high-pressure system; forgetting that 13R and 13D systems are also tested at 200 psi for two hours; mixing NFPA 13 hanger and bracing requirements into a 13D job; and omitting the seismic bracing package where ASCE 7 requires it, since NFPA 13 does not itself set the seismic demand.