FST Sprinkler Systems 3 — Questions and Answers
Question 1: What type of sprinkler system uses a deluge valve and open sprinkler heads throughout the protected area?
- Wet pipe system
- Dry pipe system
- Preaction system
- Deluge system (Correct answer)
Correct answer: Deluge system
A deluge system uses open (non-heat-activated) sprinkler heads and floods all heads simultaneously when the deluge valve opens.
Question 2: Which NFPA standard specifically governs the installation of sprinkler systems in one- and two-family dwellings?
- NFPA 13
- NFPA 13D (Correct answer)
- NFPA 13R
- NFPA 25
Correct answer: NFPA 13D
NFPA 13D covers the installation of sprinkler systems in one- and two-family dwellings and manufactured homes.
Question 3: During a forward flow test of a backflow preventer on a sprinkler system, water flows downstream but the supply shows a pressure loss of 15 psi. This is most likely due to:
- A faulty pressure gauge
- Normal pressure drop across the backflow preventer (Correct answer)
- A closed gate valve downstream
- Water hammer in the main supply
Correct answer: Normal pressure drop across the backflow preventer
Reduced pressure backflow preventers and double check assemblies inherently cause a pressure drop, typically 5–15 psi, which is normal.
Question 4: What is the purpose of an inspectors test connection (ITC) on a wet pipe sprinkler system?
- To drain the system for maintenance
- To simulate operation of the most remote sprinkler and test alarm devices (Correct answer)
- To measure static system pressure
- To flush debris from the system riser
Correct answer: To simulate operation of the most remote sprinkler and test alarm devices
The ITC simulates activation of the hydraulically most remote sprinkler to test the water motor gong, electric alarm, and flow switch without actually discharging sprinklers.
Question 5: ESFR (Early Suppression Fast Response) sprinklers are designed primarily to protect:
- Light hazard office occupancies
- High-piled storage occupancies (Correct answer)
- Residential occupancies
- Kitchen cooking equipment
Correct answer: High-piled storage occupancies
ESFR sprinklers deliver large water droplets at high pressure to penetrate fire plumes in high-challenge storage environments.
Question 6: A sprinkler system piping inspection reveals internal tuberculation and heavy corrosion. Which corrective measure is most appropriate?
- Increase system pressure to clear blockages
- Perform an obstruction investigation per NFPA 25 (Correct answer)
- Replace only the corroded heads
- Add antifreeze to the system
Correct answer: Perform an obstruction investigation per NFPA 25
NFPA 25 requires an obstruction investigation when internal corrosion or tuberculation is discovered, which may include flushing or pipe replacement.
Question 7: Which type of preaction sprinkler system requires BOTH a detection system signal AND a sprinkler head to open before water enters the piping?
- Single-interlock preaction system
- Double-interlock preaction system (Correct answer)
- Non-interlock preaction system
- Wet preaction system
Correct answer: Double-interlock preaction system
A double-interlock preaction system requires both detection activation and sprinkler head opening to allow water flow, providing the highest protection against accidental discharge.
FST Sprinkler Systems 3
What type of sprinkler system uses a deluge valve and open sprinkler heads throughout the protected area?