🔍 Key Concepts

• Cartridge-operated extinguishers and which agents are commonly used with this design • Differences in how water/foam, dry chemical, and CO₂ look inside the shell (liquid vs powder vs gas) • How the gas pressure cartridge shown in the cutaway is used to expel the main agent, not as the agent itself

💭 Think About

• Look closely at the cutaway inside the main cylinder: does it appear to hold liquid, powder, or gas space? • Think about which agent types typically need an external gas cartridge to pressurize the cylinder just before use. • Consider how the hose and nozzle are shaped: is that more typical for a streaming liquid, a foamy solution, or a powder discharge?

✅ Before You Answer

• Verify which agents from the choices are normally stored as liquids in the cylinder versus as compressed gas only. • Confirm that the small green cylinder on the side is just the propellant gas, not the extinguishing agent you’re being asked about. • Eliminate any option where the agent itself would already be stored under high pressure in the main cylinder, making a separate gas pressure cartridge unnecessary.