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Sprinkler System Lab

Take the parts apart, name them, and watch the water.

Dry pipe valve and trim · soonControl valves: OS&Y, butterfly, PIV · soonBackflow preventers · soonFire department connection · soonFire pump room · soon

Wet alarm check valve and trim

The riser in most sprinklered buildings: water held behind a check valve, an alarm line that fills when water moves, and a gong that rings with no power.

OUTSIDE WALL↑ TO THE SPRINKLERS↑ FROM THE WATER SUPPLYTO DRAINTO DRAINTO DRAININSPECTOR’S TEST — AT THE FAR END OF THE SYSTEMAlarm check valveControl valve (OS&Y)Retard chamberWaterflow pressure switchWater motor gongSupply pressure gaugeSystem pressure gaugeClapperDrain restrictionAlarm line shutoff valveMain drain valveTamper switchInspector’s test valveSight glass and test orifice
Water A little water Empty pipeTypical arrangement — trim and parts vary by manufacturer.
STEP 1 OF 7

Standby. Water fills the riser above and below the clapper at about the same pressure. The clapper rests on its seat and the alarm line is empty. NFPA 25 §13.4.1

Pairs with the NICET Level I Water-Based course and the practice exam. Frequencies are from NFPA 25 (2023 edition); check the edition your AHJ enforces. Drawings are generic schematics, not to scale.
Sprinkler System Lab — Take the Parts Apart | LifeSafetyWiki