Type DN-5 Corrosion Resistant Duct Nozzle

Inspect for water or air leakage from bonnet cover and outlet drain; verify no external moisture on diaphragm chamber; perform annual full trip test to verify diaphragm response and proper valve opening

Clean strainer in diaphragm chamber supply control valve; inspect for sediment, corrosion debris, or mineral deposits; perform internal inspection of strainers every 5 years per NFPA 25; replace if significant blockage detected

Verify dry pilot line air pressure maintained at design pressure (typically 40-50 psi); check for air leaks at connections; ensure air drier functioning and dew point below lowest ambient temperature; test pressure gauge reading weekly

Inspect all deluge nozzles/sprinklers for corrosion, mechanical damage, or buildup; verify proper orientation and alignment; check for blockage or paint over orifices; ensure DN-5 duct nozzles maintain HALAR coating integrity

Check for external corrosion on valve body, actuators, and piping; verify bonnet bolts are tight; inspect manual reset actuator (MRA-1) for damage; ensure dry pilot actuators (DP-1/DP-2) have no water/air leakage at drain outlet