Free EVT F7 practice test: Fire Apparatus Foam Systems

Free EVT F7 practice test: 10 questions

Questions from our F7 bank, written to EVTCC's learning objectives and the 2024 NFPA 1900 and 1910. Tap an answer to see if you're right and why, or switch to Timed for the real test's pace. Every answer is below each question.

1. Class A foam concentrate is formulated primarily for fires involving which type of fuel?

   AOrdinary combustibles such as wood, paper, and brush BHydrocarbon liquids such as gasoline and diesel CPolar solvents such as alcohols and ketones DEnergized electrical equipment and switchgear
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   Answer: A. Ordinary combustibles such as wood, paper, and brush

   Class A foam acts as a wetting agent that lowers water's surface tension so it penetrates ordinary combustibles like wood and brush. Flammable-liquid and polar-solvent fires require Class B foam.

   • B: Gasoline and diesel are hydrocarbon liquids, which need Class B foam.
   • C: Alcohols and ketones need alcohol-resistant Class B foam.
   • D: Water-based foam is not applied to energized equipment at all.

2. Class B foam concentrate is intended for use on which of the following?

   AFlammable and combustible liquid fires BDeep-seated wood and brush fires CEnergized electrical equipment DCombustible metal fires
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   Answer: A. Flammable and combustible liquid fires

   Class B foam builds a vapor-suppressing blanket over flammable and combustible liquids. Ordinary combustibles use Class A foam, and burning metals require special dry agents.

   • B: Wood and brush are Class A fuels handled by Class A foam.
   • C: Foam is not used on energized electrical equipment.
   • D: Combustible metals require dry powder agents, not foam.

3. When a foam system is set for '3% proportioning,' what does this mean?

   A3 parts foam concentrate are mixed with 97 parts water to make 100 parts solution B3 parts water are added to 97 parts concentrate to make the solution CThe finished foam expands to three times the volume of solution used DThe discharge delivers 3 gallons of finished solution every minute
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   Answer: A. 3 parts foam concentrate are mixed with 97 parts water to make 100 parts solution

   A 3% setting means the finished solution is 3% concentrate and 97% water by volume. The number does not describe expansion or flow rate.

   • B: This inverts the ratio; the 3% names the concentrate fraction.
   • C: That is expansion ratio, not a proportioning setting.
   • D: That is a flow rate; a proportioning percentage holds across flows.

4. Class A foam is typically proportioned within which range?

   A0.1% to 1% B3% to 6% C6% to 12% D10% to 20%
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   Answer: A. 0.1% to 1%

   Class A foam is used at low concentrations, commonly 0.1% to 1%, adjusted for the fuel and whether it is used for attack or exposure protection. The 3%/6% range is typical of Class B foams.

   • B: 3% to 6% is the typical Class B range, not Class A.
   • C: 6% to 12% is far above Class A proportioning.
   • D: 10% to 20% is not a foam proportioning range.

5. What is the primary advantage of alcohol-resistant AFFF (AR-AFFF) over standard AFFF?

   AIt forms a polymeric membrane that resists breakdown on polar (water-miscible) fuels BIt can be discharged directly onto energized electrical equipment safely CIt is used straight from the pail and requires no proportioning DIt expands to a higher ratio than any other foam concentrate made
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   Answer: A. It forms a polymeric membrane that resists breakdown on polar (water-miscible) fuels

   AR-AFFF deposits a polymeric membrane that protects the foam blanket from being destroyed by polar solvents such as alcohols and ketones. Standard AFFF breaks down quickly on those fuels.

   • B: No foam is applied to energized equipment, so this is no advantage.
   • C: AR-AFFF is a concentrate and must be proportioned like standard AFFF.
   • D: Expansion ratio is not what separates AR-AFFF from standard AFFF.

6. The fire service transition to fluorine-free (F3) foams is driven primarily by concerns over which issue?

   APersistent PFAS chemicals in traditional fluorinated foams BF3 concentrate being cheaper to manufacture and buy CFluorinated concentrates being flammable in storage DF3 concentrate being usable without any water
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   Answer: A. Persistent PFAS chemicals in traditional fluorinated foams

   Traditional AFFF and AR-AFFF contain PFAS (per- and polyfluoroalkyl substances) that persist in the environment, driving the move to fluorine-free foams. F3 foams still require water and proportioning.

   • B: Cost is not the concern driving the transition.
   • C: The concentrates are not flammable; PFAS persistence is the concern.
   • D: F3 still needs water and proportioning to make a solution.

7. A compressed air foam system (CAFS) produces finished foam by combining which elements?

   AWater, foam concentrate, and compressed air BWater and concentrate only CConcentrate and compressed air only DWater and compressed air only
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   Answer: A. Water, foam concentrate, and compressed air

   CAFS injects compressed air into an already-proportioned foam solution, producing a uniform, energized foam. All three elements are required.

   • B: Without air, the result is standard foam solution, not CAFS.
   • C: Concentrate and air alone lack the water to form solution.
   • D: Water and air without concentrate cannot make foam.

8. Foam expansion ratio is best defined as which of the following?

   AThe volume of finished foam produced from a given volume of foam solution BThe percentage of concentrate present in the finished solution CThe time the finished foam takes to drain its water back out DThe inlet pressure an eductor needs to draw concentrate
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   Answer: A. The volume of finished foam produced from a given volume of foam solution

   Expansion ratio compares the finished-foam volume to the solution volume used to make it. Low-expansion foam is roughly up to 20:1, with medium and high expansion progressively greater.

   • B: That is the proportioning percentage, not a volume comparison.
   • C: Drain time measures stability, not the volume of foam produced.
   • D: Eduction pressure is proportioning hardware, not expansion.

9. The onboard reservoir that stores foam concentrate for the proportioning system is called the what?

   AFoam cell (foam tank) BBooster tank CPrimer reservoir DSurge tank
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   Answer: A. Foam cell (foam tank)

   Concentrate is stored in a dedicated foam cell, separate from the water booster tank. The concentrate pickup line draws from this reservoir.

   • B: The booster tank holds water, not concentrate.
   • C: The primer reservoir serves the pump primer, not foam.
   • D: A surge tank is unrelated to foam concentrate storage.

10. An in-line foam eductor introduces concentrate into the water stream using which principle?

    AThe venturi effect, where a pressure drop creates suction BPositive-displacement pumping of the concentrate CCompressed air injection DGravity feed from an elevated tank
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    Answer: A. The venturi effect, where a pressure drop creates suction

    As water passes through the eductor's restricted throat, velocity rises and pressure drops, creating a vacuum that draws concentrate into the stream. This is the venturi principle.

    • B: An eductor has no concentrate pump; it relies on suction.
    • C: Air injection describes CAFS, not an eductor.
    • D: An eductor draws concentrate by suction, not gravity.