FREE STUDY · 6 MIN LESSON
System Types & Components: Wet, Dry, Preaction, Deluge
Read the lesson without an account, then create a free account to use the free narrated cards in the app. No payment card required. Knowledge practice does not replace approved training or any skills evaluation your certifying body requires.
Walking the Systems in the Riser Room
- Four water-based systems, and each one is serviced differently.
- Wet, dry, preaction, deluge — plus the valves, pumps, and supply.
- Get the system type right and the whole ITM plan follows.
Wet and Dry Pipe
- Wet pipe = water always in the pipe; instant discharge.
- Dry pipe = air holds water back until a head opens and the valve trips.
- Dry systems protect freezing, unheated spaces.
Preaction vs Deluge
- Preaction = CLOSED heads + a separate detector; two events, then flow.
- Deluge = OPEN heads; the valve releases and ALL heads flow at once.
- The heads open or closed is the whole distinction.
Standpipes and Control Valves
- Standpipe I = fire dept 2.5", II = occupant 1.5", III = both.
- Control valves stay normally OPEN and secured.
- A closed control valve is the #1 cause of system failure.
Fire Pump, Supply, FDC, and Backflow
- Fire pump boosts pressure/flow when supply alone is short.
- Supply = mains (Ch 7), tanks (Ch 9), and the FDC (quarterly).
- Backflow device = annual forward flow test at demand.
Don't Mix Preaction and Deluge
- Preaction has CLOSED heads — water waits for a head to open.
- Deluge has OPEN heads — the valve releases and all flow together.
- And dry pipe DOES fill — once the valve trips.
Systems Identified
- You can name the four systems and their components now.
- Cards next — lock the preaction-vs-deluge direction in.
Quick Self-Check
- Answer in your head before the cards:
- Which two systems use a separate detector, and which has open heads?
- And what's the #1 cause of system failure?