F7 Foam Systems — practice test
F7 is the EVT Foam Systems exam. It tests whether you understand how apparatus makes and delivers foam - the concentrate, the proportioner and the delivery - not just which button turns it on. Techs fail it by knowing the plumbing but not the numbers: what a 3% system is actually doing, why an eductor stops drawing, or how CAFS differs from a standard foam system.
Studying for F7 (Foam Systems)? Overhaul Prep has 36 verified F7 questions written to the current task list — in the same formats the real exam uses (direct, Technician A/B, EXCEPT and most-likely-cause). Every answer comes with a written explanation, so you learn why instead of memorising a letter.
What's on the F7 test
F7 covers foam concentrates (Class A vs Class B, AR-AFFF, and the move to fluorine-free foams), proportioning methods (in-line eductors, around-the-pump, balanced-pressure and direct-injection), CAFS, foam-system components, calibration and testing of proportioners, and troubleshooting and maintenance. Expect concept and cause/effect over button-pushing.
High-yield F7 topics
The material that shows up year after year. If you're short on time, start here.
- Class A foam runs about 0.1-1%; Class B is typically 3% or 6% - know what the percentage means.
- An eductor that stops drawing is usually a plugged pickup/strainer or the wrong flow/inlet pressure for its rating.
- CAFS adds compressed air to water-and-concentrate for a durable, longer-throw foam.
- Direct-injection and balanced-pressure systems meter concentrate independent of flow; eductors do not.
- Flush foam systems after use so concentrate does not gum up lines and proportioners.
Where techs lose points on F7
Good technicians miss these — not from lack of skill, but because the question is built to catch them.
- Confusing proportioning percentage (concentrate-to-solution) with expansion ratio (finished-foam-to-solution).
- Assuming any concentrate works in any system or on any fire class.
- Forgetting an eductor's flow and inlet pressure must match its rating or it will not draw.
A study plan that works for F7
Roughly two weeks of real preparation, in the order that actually builds on itself.
- Learn the concentrate types and the percentage each uses, and what the percentage means.
- Learn each proportioning method and how to identify it on a truck.
- Work CAFS vs standard foam and the no-foam / wrong-ratio troubleshooting logic.
- Finish on calibration, testing and post-use flushing.
Sample F7 questions
Straight from the bank — answers highlighted, with the explanation underneath.
Class A foam concentrate is formulated primarily for fires involving which type of fuel?
- Ordinary combustibles such as wood, paper, and brush
- Flammable liquids such as gasoline
- Polar solvents such as alcohol
- Energized electrical equipment
Class B foam concentrate is intended for use on which of the following?
- Flammable and combustible liquid fires
- Deep-seated wood and brush fires
- Energized electrical equipment
- Combustible metal fires
When a foam system is set for '3% proportioning,' what does this mean?
- 3 parts foam concentrate are mixed with 97 parts water to make 100 parts solution
- 3 parts water are added to 97 parts concentrate
- The finished foam expands to 3 times its original volume
- 3 gallons of solution are discharged each minute
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