FST Sprinkler Systems 2 — Questions and Answers
Question 1: What is the minimum water supply duration required for a light hazard sprinkler system per NFPA 13?
- 15 minutes
- 30 minutes (Correct answer)
- 60 minutes
- 90 minutes
Correct answer: 30 minutes
NFPA 13 requires a minimum 30-minute water supply duration for light hazard occupancies.
Question 2: Which type of sprinkler head is designed to discharge water in a pattern that does not wet the ceiling?
- Standard upright sprinkler
- Sidewall sprinkler
- ESFR sprinkler
- In-rack sprinkler (Correct answer)
Correct answer: In-rack sprinkler
In-rack sprinklers are positioned within storage racks and direct water downward without wetting the ceiling.
Question 3: A wet pipe sprinkler system is found to have a constant drip from a sprinkler head that has not activated. What is the most likely cause?
- Excessive system pressure
- A corroded or damaged deflector
- A leaking sprinkler seat or cracked bulb (Correct answer)
- Improper pipe slope
Correct answer: A leaking sprinkler seat or cracked bulb
Constant dripping from an unactivated sprinkler typically indicates a failed heat-sensitive element or a leaking seat.
Question 4: Under NFPA 13, what is the maximum distance allowed between sprinklers in a light hazard occupancy with standard spray sprinklers?
- 12 feet
- 15 feet
- 20 feet (Correct answer)
- 25 feet
Correct answer: 20 feet
NFPA 13 allows a maximum 15-foot spacing between sprinklers in light hazard occupancies, but the maximum coverage area per head governs; 15 ft is the standard answer for spacing.
Question 5: What component in a dry pipe sprinkler system prevents water from entering the piping until a sprinkler activates?
- Check valve
- Dry pipe valve (Correct answer)
- Alarm valve
- Deluge valve
Correct answer: Dry pipe valve
The dry pipe valve holds pressurized air or nitrogen in the piping and only opens to admit water when pressure drops after sprinkler activation.
Question 6: Which sprinkler temperature rating classification has a maximum ceiling temperature of 100°F per NFPA 13?
- Ordinary (135–170°F) (Correct answer)
- Intermediate (175–225°F)
- High (250–300°F)
- Extra High (325–375°F)
Correct answer: Ordinary (135–170°F)
Ordinary rated sprinklers (135–170°F activation) are used where maximum ceiling temperatures do not exceed 100°F.
Question 7: A fire sprinkler system inspector notices the main drain test produces a residual pressure significantly lower than the system design pressure. What does this indicate?
- Normal system operation
- A possible obstruction or inadequate water supply (Correct answer)
- The alarm check valve is stuck open
- Excess air in the system
Correct answer: A possible obstruction or inadequate water supply
A low residual pressure during a main drain test suggests a potential obstruction in the supply piping or an inadequate municipal water supply.
FST Sprinkler Systems 2
What is the minimum water supply duration required for a light hazard sprinkler system per NFPA 13?