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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 orificeSupply pressure gauge
Water A little water Empty pipeTypical arrangement — trim and parts vary by manufacturer.
PART

Supply pressure gauge

Also called: lower gauge, water supply gauge

The gauge below the clapper. It shows the pressure the water supply delivers to the riser, and it is the gauge read for the static and residual readings in a main drain test.

WHAT THE INSPECTOR CHECKS
  • Inspected for condition and a normal reading; replaced or checked against a calibrated gauge, and must read within 3% of full scale. NFPA 25 §13.2.4
HOW OFTEN (NFPA 25, 2023)
Inspection (water gauge)quarterlyNFPA 25 §13.2.4
Replace or calibrate5 yearsNFPA 25 §13.2.4
COMMON DEFICIENCY

Needle stuck, face fogged, or no record of replacement or calibration in the last five years. NFPA 25 §13.2.4

Read the article →
PARTS IN THIS ASSEMBLY
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