FST Sprinkler Systems 4 — Questions and Answers
Question 1: Per NFPA 25, how often must a full flow trip test be conducted on a dry pipe sprinkler system?
- Monthly
- Quarterly
- Annually (Correct answer)
- Every 3 years
Correct answer: Annually
NFPA 25 requires an annual full flow trip test of dry pipe valves to verify proper operation and measure trip time.
Question 2: What is the maximum permitted trip time for a dry pipe valve when tested under full flow conditions per NFPA 13?
- 30 seconds
- 60 seconds (Correct answer)
- 90 seconds
- 120 seconds
Correct answer: 60 seconds
NFPA 13 requires that water reach the inspector's test connection within 60 seconds when the dry pipe valve trips under full flow test conditions.
Question 3: A sprinkler system protecting a commercial kitchen uses sprinklers with what color coding on the frame or bulb to indicate a high temperature rating?
- Orange or red (Correct answer)
- Blue
- Green
- Purple
Correct answer: Orange or red
Red-coded sprinklers indicate a high temperature rating (250–300°F), and orange indicates intermediate (250°F range), both appropriate for high-heat cooking environments.
Question 4: What is the primary purpose of a hydraulic design information sign posted at a sprinkler system riser?
- To list the names of installers and inspectors
- To display the minimum required water supply for the system (Correct answer)
- To show the location of all sprinkler heads
- To indicate the type of fire alarm panel connected
Correct answer: To display the minimum required water supply for the system
The hydraulic nameplate provides the design pressure, flow rate, and hazard classification so inspectors can verify adequate water supply during acceptance or periodic testing.
Question 5: In a wet pipe sprinkler system, what is the function of the alarm check valve?
- To prevent backflow into the municipal water supply
- To allow water flow to ring the water motor gong when a sprinkler activates (Correct answer)
- To isolate individual branch lines for maintenance
- To regulate system working pressure
Correct answer: To allow water flow to ring the water motor gong when a sprinkler activates
The alarm check valve opens under sprinkler flow conditions, directing water to the retard chamber and then to the water motor gong to sound a local alarm.
Question 6: Which condition would require a sprinkler head to be replaced immediately per NFPA 25?
- A sprinkler head with a slightly dusty deflector
- A painted sprinkler head (Correct answer)
- A sprinkler installed in an area with a lower hazard than designed
- A sprinkler head missing its color coding label
Correct answer: A painted sprinkler head
Painted sprinkler heads must be replaced immediately because paint alters the thermal response characteristics and may prevent proper activation.
Question 7: What is the minimum clearance required between the top of storage and sprinkler deflectors in a standard sprinkler system per NFPA 13?
- 12 inches
- 18 inches (Correct answer)
- 24 inches
- 36 inches
Correct answer: 18 inches
NFPA 13 requires a minimum 18-inch clearance between the top of storage and sprinkler deflectors to allow proper water distribution.
FST Sprinkler Systems 4
Per NFPA 25, how often must a full flow trip test be conducted on a dry pipe sprinkler system?