NICET Special Hazard Suppression Systems 2 — Questions and Answers
Question 1: Which NFPA standard governs dry chemical extinguishing systems?
- NFPA 11
- NFPA 12
- NFPA 17 (Correct answer)
- NFPA 750
Correct answer: NFPA 17
NFPA 17 is the Standard for Dry Chemical Extinguishing Systems and covers design, installation, testing, and maintenance requirements.
Question 2: A CO2 local application system is the preferred approach when protecting a hazard that:
- Is located in a tightly enclosed vault with no personnel access
- Cannot be economically enclosed and total flooding is impractical (Correct answer)
- Involves only Class A deep-seated fires
- Is in a normally occupied space requiring personnel warning time
Correct answer: Cannot be economically enclosed and total flooding is impractical
Local application directs CO2 directly at the fuel surface or equipment when building a total-flooding enclosure is impractical or uneconomical.
Question 3: What is the primary purpose of a pre-discharge alarm in a total flooding gaseous suppression system?
- To trigger the suppression agent release
- To warn occupants to evacuate before the agent discharges (Correct answer)
- To automatically notify the fire department
- To shut down all electrical equipment in the hazard area
Correct answer: To warn occupants to evacuate before the agent discharges
Pre-discharge alarms provide an audible/visual warning so personnel can evacuate the hazard area before the agent is released, preventing exposure to potentially hazardous concentrations.
Question 4: Halon 1301 was phased out of new production primarily because of:
- High acute toxicity to building occupants at design concentrations
- Its ozone-depleting properties identified under the Montreal Protocol (Correct answer)
- Poor fire suppression performance compared to CO2
- Prohibitive manufacturing costs that made it economically unviable
Correct answer: Its ozone-depleting properties identified under the Montreal Protocol
Halon 1301 contains bromine, a highly effective ozone-depleting substance; its production was banned in developed countries by 1994 under the Montreal Protocol.
Question 5: Which foam type is most effective at controlling three-dimensional and flowing liquid hydrocarbon fires?
- High-expansion foam
- Protein foam
- AFFF (Aqueous Film Forming Foam) (Correct answer)
- Air-aspirated protein foam
Correct answer: AFFF (Aqueous Film Forming Foam)
AFFF creates a thin aqueous film that spreads across the fuel surface rapidly, making it uniquely effective against spill fires and three-dimensional flowing fuel fires.
Question 6: Per NFPA 750, what droplet size criterion defines a water mist system discharge?
- All droplets must be smaller than 100 microns
- The Dv0.99 (99th percentile droplet diameter) must be less than or equal to 1000 microns (Correct answer)
- Average droplet diameter must be greater than 2000 microns
- All droplets must be larger than 500 microns to ensure surface cooling
Correct answer: The Dv0.99 (99th percentile droplet diameter) must be less than or equal to 1000 microns
NFPA 750 defines water mist as a water spray for which the Dv0.99 is less than 1000 microns at the minimum design operating pressure, distinguishing it from conventional sprinkler spray.
Question 7: Under NFPA 2001, FK-5-1-12 (Novec 1230) is classified as which agent type?
- Inert gas clean agent
- Halocarbon clean agent (Correct answer)
- Dry chemical agent
- CO2-based clean agent
Correct answer: Halocarbon clean agent
FK-5-1-12 is a fluorinated ketone and is classified as a halocarbon clean agent under NFPA 2001, alongside HFCs such as HFC-227ea and HFC-125.
NICET Special Hazard Suppression Systems 2
Which NFPA standard governs dry chemical extinguishing systems?