Installation Coordination and Documentation
The paperwork trail
Design output is not finished at the calculation. Working plans, hydraulic calculations, and equipment data go to the authority having jurisdiction for approval before installation; approved plans become the controlled document, and every field change goes through an RFI or revised drawing rather than a verbal instruction. Closeout requires as-built drawings, an operations and maintenance manual, the Owner's Certificate, and a Material and Test Certificate documenting flushing and hydrostatic testing.
Tests you must be able to state
Hydrostatic test at 200 psi for 2 hours, or at 50 psi above the working pressure where that pressure exceeds 150 psi. Underground mains are flushed before connection to achieve the required scour velocity, and air testing (about 40 psi held for 24 hours) applies to dry systems. Rough-in and final inspections must be scheduled with the AHJ at the milestones the local program defines, and the system cannot be covered or concealed before those sign-offs.
Coordination
Sprinkler layout drives and is driven by structure, ceiling systems, ducts, lights, and racking. Watch the 18 in. clearance below deflectors to storage, firestopping at rated penetrations, and impairment and hot-work procedures whenever a system is taken out of service. Spare sprinklers and the correct wrench must be left on site.
Worked example: a system with a working pressure of 120 psi is hydrostatically tested at 200 psi for 2 hours, since 120 psi does not exceed 150 psi.
Rule of thumb: spare sprinkler cabinet - 6 spares for 300 or fewer sprinklers, 12 for 301 to 1000, and 24 above that.