Concept · Zone I · Extinguishers
Classes of fire A, B, C, D and K, and the extinguisher for each
A class of fire names what is burning, and an extinguisher label lists the classes that unit can put out. In the Study Material for the F-80 Certificate of Fitness, each class is tied to a fuel and to a mark on the label. This page sits under the Zone I page (Extinguishers).
Plan ref I1Updated October 25, 2026
Fuel first, letters second
Every class letter answers one question: what is the fire feeding on? Bedding and paper in a dorm are one answer. Paint thinner in the maintenance closet is another. Oil in a commercial kitchen is a third (Source: Study Material §15.1).
Four of the five letters name a fuel. One of them does not, and a practice question can turn on that one.
Then read the label as a list. A unit marked with two or three classes covers each of them. A unit marked with one class covers that one only. The PASS method helps only once you are holding the right unit.
The label is printed on the unit. The paper tag that hangs from it is a separate record, covered on the extinguisher tags page.
Round: match the fire to the label
Checkpoint round
0 of 6 checked · 0 cleared
Practice questions written for study, not taken from the test. The real F-80 is a multiple-choice test on a touch-screen computer at FDNY Headquarters.
Skim the four options first: each one points to a fuel or a unit. Then find the fuel in the stem and strike every option built for another.
How the checkpoint round works
Read the options first and rule out the ones that break a rule, then pick from what is left. After you answer, the debrief explains every option and scores your strikes. Keys: 1–5 or A–E answer, Shift with a number rules that option out, the arrow keys move.
Checkpoint 1 of 6
Checkpoint 01
A small grease fire breaks out in a shelter kitchen’s deep fryer. Which portable fire extinguisher must the coordinator ensure is used to extinguish the flames?
Rule out what you can with the ✕ buttons, then choose. The debrief for every option opens here.
- ACorrect: Class K extinguishers are made for cooking oils and fats; the agent forms a soapy foam that holds in the vapors.
- BClass A covers ordinary combustibles like wood and paper; it is not rated for cooking grease.
- CWater on burning grease can splash and spread the fire, which is why water units are only for ordinary combustibles.
- DCarbon dioxide is not rated for commercial cooking fires; the Class K label is what to look for at a fryer.
Checkpoint 02
A fire breaks out in a shelter’s server room involving an energized electrical panel. Which type of portable fire extinguisher should the coordinator direct staff to use?
Rule out what you can with the ✕ buttons, then choose. The debrief for every option opens here.
- AFoam conducts electricity, and an A and B rating has no C, so it is not safe on live equipment.
- BClass K agents can conduct electricity and are for cooking oils, used only after the power is off.
- CWater conducts electricity, which makes it dangerous on an energized panel.
- DCorrect: The C in ABC means the agent does not conduct electricity, so it is safe on live electrical equipment.
Checkpoint 03
A coordinator is equipping a renovated residential wing with furniture, linens and several electrical appliances. Which extinguisher setup best fits these hazards?
Rule out what you can with the ✕ buttons, then choose. The debrief for every option opens here.
- AWater handles bedding and furniture but is unsafe on energized appliances.
- BClass D is for burning metals such as magnesium; household appliances are not that hazard.
- CClass K is for commercial cooking oils, and neither unit here covers live electrical equipment safely.
- DCorrect: ABC extinguishers cover ordinary combustibles and electrical equipment, which matches furnishings, linens, and appliances.
Checkpoint 04
An extinguisher is marked with a green triangle. Which kind of fire is it meant for?
Rule out what you can with the ✕ buttons, then choose. The debrief for every option opens here.
- ACorrect: the green triangle is the Class A symbol, for ordinary combustibles like wood, paper and cloth.
- BFlammable liquids are Class B, shown by a red square, not a green triangle.
- CLive electrical fires are Class C, shown by a blue circle, and need a nonconductive agent.
- DCooking fats and grease are Class K fires, handled by a wet chemical unit, not a green-triangle one.
Checkpoint 05
An extinguisher label shows a yellow five-point star with the letter D. On which kind of fire is this extinguisher meant to be used?
Rule out what you can with the ✕ buttons, then choose. The debrief for every option opens here.
- ACooking oils and fats are Class K fires; that extinguisher is marked with the letter K, not a star.
- BFlammable liquids are Class B fires, marked with a square (red if in color), not a star.
- CCorrect: the star with the letter D marks Class D, the agent for burning metals like magnesium, titanium or sodium.
- DLive electrical equipment is Class C, marked with a circle (blue if in color).
Checkpoint 06
Why is there no portable fire extinguisher rated for Class C fires only?
Rule out what you can with the ✕ buttons, then choose. The debrief for every option opens here.
- ACorrect: C only says the agent is safe on live electrical fires, so it is always paired with B or AB.
- BOut: the Study Material does not leave electrical fires to sprinklers; BC and ABC units are made for them.
- CK is the class for cooking oils and fats in kitchens; it never replaced the C rating.
- DWater conducts electricity; live electrical fires need a nonconductive agent, which is what C means.
The five classes on the label
Classes of fire and their label marks, Study Material §15.1
| Class | What burns | Label mark | Color, if in color |
|---|---|---|---|
| A | Ordinary combustibles: wood, paper, some plastics, textiles | A triangle with the letter A | Green |
| B | Flammable liquids and gases, such as oil and gasoline | A square with the letter B | Red |
| C | Fires that involve live electrical equipment | A circle with the letter C | Blue |
| D | Combustible metals, such as magnesium, titanium and sodium | A five-point star with the letter D | Yellow |
| K | Cooking media (fats, grease and oils) in commercial cooking | The letter K | Not given |
Source: Source: Study Material §15.1. C is the odd letter: it means the agent does not conduct electricity. Once the equipment is de-energized, a unit for Class A or B fires may be used.
Which unit is on the wall
Three common extinguisher types in the Study Material
| Point | ABC dry chemical | BC | Class A water (APW) |
|---|---|---|---|
| Classes it covers (differs) | A, B and C | B and C | A only |
| Agent (differs) | Dry chemical | Sodium or potassium bicarbonate | Water, air-pressurized |
| Usual color (differs) | Red | Red | Silver |
| Usual size (differs) | 5 to 20 lb | 5 to 100 lb or larger | About 3 ft tall and about 25 lb |
| Where the Study Material puts it (differs) | The primary unit in offices, hotels, theaters and classrooms | Flammable liquid and electrical equipment fires | Buildings that mostly hold Class A materials |
Shaded rows marked ≠ are the points where at least one column differs from the others.
No extinguisher is made with a B alone or a C alone (Source: Study Material §15.1). The C is always attached to a B or an AB rating.
Worked: a solvent fire in the maintenance closet
A can of paint thinner is burning in the maintenance closet. Which unit fits the fuel?
- AA silver water (APW) unitOut in round 3
- BA BC dry chemical unitKeep
- CA Class K wet chemical unitOut in round 2
- DA Class D unitOut in round 1
- Round 1 — rule out D.D is for combustible metals. Paint thinner is a flammable liquid.
- Round 2 — rule out C.K agents are made for cooking oils and fats in commercial kitchens.
- Round 3 — rule out A.The Study Material says an APW unit should be used only on ordinary combustible fires.
B. The B on its label covers flammable liquids (Source: Study Material §15.1). An ABC unit would also fit, but it is not one of the options.
Class K and live power
Some Class K agents conduct electricity. The Study Material says to use them only after the power to the appliance is turned off (Source: Study Material §15.1).
Where the rule is written
- Source: Study Material §15.1Classes A, B, C, D and K, their marks, and why no C-only unit exists.
- Source: Study Material §15.2Labels show recommended and unacceptable uses as pictures.
- Source: Study Material p. 60The class chart starts here (rev. January 2026, as of October 2026).
Next exit: the App Store
F-80 is on the App Store for iPhone and iPad. On any other device, the free practice here is the way through.