Annual Inspection Findings on a Wet-Pipe System: What Must Be Corrected and When?
A 10-year-old wet-pipe system in a 6-story office building has a 6 in riser. During the annual inspection in March, the technician records a static pressure of 74 psi and a flowing pressure of 58 psi on the main drain test; the previous year's baseline was 72 psi static and 66 psi flowing. The riser gauge was installed 7 years ago and reads 1 psi lower than a calibrated gauge. The alarm check valve has a slight leak at the retarding chamber. The spare sprinkler cabinet contains 2 spare heads for 1,200 sprinklers. The owner wants to defer the 5-year internal pipe inspection because the system has never had a failure. The system is in a Maryland county, and the owner asks whether the annual inspection can be signed off.
1. Identify the deficiencies in the inspection record and state the required actions and priorities.
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The main drain test changed materially: the prior drop was 72 - 66 = 6 psi, while the current drop is 74 - 58 = 16 psi. NFPA 25 requires comparison with the baseline; a 10 psi increase in pressure drop indicates a possible obstruction, partially closed valve, or supply change. That must be investigated before the inspection is signed off.
The alarm check valve leak at the retarding chamber must be repaired. The gauge is 7 years old, past the 5-year test/replacement interval. The spare sprinkler inventory is far below the required number for 1,200 sprinklers. The 5-year internal pipe inspection cannot simply be deferred because there has been no failure; it must be scheduled or a documented AHJ-approved alternative obtained.
2. How should the gauge and main drain test results be evaluated under NFPA 25?
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The gauge cannot be accepted merely because it is only 1 psi off. NFPA 25 requires gauges to be tested or replaced on a 5-year interval; at 7 years it is overdue. The technician should replace or recalibrate it and record the result.
For the main drain, NFPA 25 does not judge adequacy by a single fixed pressure drop. It compares the current flowing pressure and drop with the original baseline. The jump from a 6 psi drop to a 16 psi drop is a warning sign. The contractor should check valve position, strainers, and possible scale or foreign material, then re-test. If the flow returns to baseline, document it; if not, investigate the supply and piping further.
3. What is required for spare sprinklers and the 5-year internal inspection?
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For 1,200 sprinklers, the spare sprinkler cabinet should contain 24 spare sprinklers of the correct types and temperature ratings, not 2. The spares must match the installed sprinklers and include a sprinkler wrench. The inspector should cite this as a deficiency and require replenishment.
The 5-year internal pipe inspection is a scheduled maintenance requirement, not a discretionary item based on a clean service history. The owner may request a deferral only through the process allowed by the authority having jurisdiction; the contractor should not sign off the annual inspection as fully compliant while it remains overdue. The inspection record should list the deficiency, the corrective action, and the target date.