FPE Fire Suppression Systems & Technology 3 — Questions and Answers
Question 1: Which type of sprinkler is required in rack storage applications where in-rack sprinklers are installed below the top tier?
- Standard upright sprinklers
- In-rack sprinklers with water shields (Correct answer)
- Residential sprinklers
- Extended coverage sprinklers
Correct answer: In-rack sprinklers with water shields
NFPA 13 requires water shields (also called water barriers or shields) on in-rack sprinklers below the top level to prevent prewetting from upper sprinklers.
Question 2: A wet chemical suppression system is most commonly installed to protect which type of hazard?
- Flammable liquid storage rooms
- Commercial cooking equipment and hood systems (Correct answer)
- Electrical switchgear rooms
- Paint spray booths
Correct answer: Commercial cooking equipment and hood systems
Wet chemical systems (NFPA 17A) are specifically designed for commercial cooking equipment, suppressing grease fires through saponification.
Question 3: In a CO2 total flooding system, the minimum design concentration for protecting a Class B surface fire hazard per NFPA 12 is:
- 25%
- 34% (Correct answer)
- 50%
- 65%
Correct answer: 34%
NFPA 12 requires a minimum CO2 concentration of 34% (by volume) for surface fire protection of Class B hazards.
Question 4: What does the term 'K-factor' represent in sprinkler system hydraulics?
- Pipe friction loss coefficient
- Sprinkler discharge coefficient relating flow to pressure (Correct answer)
- Head loss across a backflow preventer
- Velocity pressure correction factor
Correct answer: Sprinkler discharge coefficient relating flow to pressure
The K-factor is the discharge coefficient in the formula Q = K√P, relating sprinkler flow (gpm) to operating pressure (psi).
Question 5: Under NFPA 750, water mist systems are classified by operating pressure. What pressure range defines a 'low-pressure' water mist system?
- Below 175 psi (Correct answer)
- 175 to 500 psi
- 500 to 1,000 psi
- Above 1,000 psi
Correct answer: Below 175 psi
NFPA 750 defines low-pressure water mist systems as those operating at or below 175 psi (12.1 bar).
Question 6: When sizing a fire pump per NFPA 20, the pump must be capable of delivering what percentage of rated capacity at churn (no-flow) pressure not exceeding what limit?
- 100% rated flow; churn pressure ≤ 110% of rated pressure
- 150% rated flow; churn pressure ≤ 140% of rated pressure
- 0% rated flow; churn pressure ≤ 140% of rated pressure (Correct answer)
- 0% rated flow; churn pressure ≤ 165% of rated pressure
Correct answer: 0% rated flow; churn pressure ≤ 140% of rated pressure
At churn (shutoff/no-flow) condition, NFPA 20 requires the net pump pressure not exceed 140% of the rated (design) pressure.
Question 7: Which suppression agent is best suited for protecting a normally occupied electronic equipment room due to its zero ozone depletion potential and low toxicity?
- Halon 1301
- Carbon dioxide (CO2)
- HFC-227ea (FM-200) (Correct answer)
- Dry chemical (ABC)
Correct answer: HFC-227ea (FM-200)
HFC-227ea has zero ozone depletion potential, low toxicity at design concentrations, and is safe for use in occupied spaces.
FPE Fire Suppression Systems & Technology 3
Which type of sprinkler is required in rack storage applications where in-rack sprinklers are installed below the top tier?