CHST-Exam Questions and Answers
100% Pass
For fire to exist, what 4 elements must be present at the same time? - ✔✔Oxygen, Fuel,
Heat Chemical Reaction
Enough oxygen to sustain combustion.
Enough heat to raise the material to its ignition temperature.
Some sort of fuel or combustible material.
The chemical reaction that is fire.
How do Air-pressurized Water Extinguishers (APW) work? - ✔✔APWs extinguish fire
by cooling the surface of the fuel to remove the "heat" element of the fire triangle.
What class of fires do Air-pressurized Water Extinguishers (APW) work on? (Class A, B,
C, D K?) - ✔✔Class A,
wood, paper, cloth, rubber, and certain plastics
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, Why cant you use an Air-pressurized Water Extinguisher, APW, on a flammable liquid
fire? - ✔✔Water is extremely ineffective at extinguishing this type of fire and may make
matters worse by the spreading the fire.
Why cant you use an Air-pressurized Water Extinguisher, APW, on a electrical fire? -
✔✔Water is a good conductor and may lead to electrocution if used to extinguish an
electrical fire.
Electrical equipment must be unplugged and/or de-energized before using a water
extinguisher on an electrical fire.
How do CO2 or Dry Chemical - Carbon Dioxide Extinguishers work? - ✔✔These
extinguishers put out fires by displacing oxygen, or taking away the oxygen element of
the fire triangle.
What type of extinguisher has a hard horn and no pressure gauge? - ✔✔CO2 or Dry
Chemical - Carbon Dioxide Extinguisher
What type of extinguisher is in a silver container? - ✔✔Air-pressurized Water
Extinguisher, APW
How do CO2 or Dry Chemical - Carbon Dioxide Extinguishers work? - ✔✔These
extinguishers put out fires by displacing oxygen, or taking away the oxygen element of
the fire triangle.
100% Pass Guarantee Emilly Charlotte, All Rights Reserved © 2025 2
100% Pass
For fire to exist, what 4 elements must be present at the same time? - ✔✔Oxygen, Fuel,
Heat Chemical Reaction
Enough oxygen to sustain combustion.
Enough heat to raise the material to its ignition temperature.
Some sort of fuel or combustible material.
The chemical reaction that is fire.
How do Air-pressurized Water Extinguishers (APW) work? - ✔✔APWs extinguish fire
by cooling the surface of the fuel to remove the "heat" element of the fire triangle.
What class of fires do Air-pressurized Water Extinguishers (APW) work on? (Class A, B,
C, D K?) - ✔✔Class A,
wood, paper, cloth, rubber, and certain plastics
100% Pass Guarantee Emilly Charlotte, All Rights Reserved © 2025 1
, Why cant you use an Air-pressurized Water Extinguisher, APW, on a flammable liquid
fire? - ✔✔Water is extremely ineffective at extinguishing this type of fire and may make
matters worse by the spreading the fire.
Why cant you use an Air-pressurized Water Extinguisher, APW, on a electrical fire? -
✔✔Water is a good conductor and may lead to electrocution if used to extinguish an
electrical fire.
Electrical equipment must be unplugged and/or de-energized before using a water
extinguisher on an electrical fire.
How do CO2 or Dry Chemical - Carbon Dioxide Extinguishers work? - ✔✔These
extinguishers put out fires by displacing oxygen, or taking away the oxygen element of
the fire triangle.
What type of extinguisher has a hard horn and no pressure gauge? - ✔✔CO2 or Dry
Chemical - Carbon Dioxide Extinguisher
What type of extinguisher is in a silver container? - ✔✔Air-pressurized Water
Extinguisher, APW
How do CO2 or Dry Chemical - Carbon Dioxide Extinguishers work? - ✔✔These
extinguishers put out fires by displacing oxygen, or taking away the oxygen element of
the fire triangle.
100% Pass Guarantee Emilly Charlotte, All Rights Reserved © 2025 2
