Which are the two types of valves used in fuel tanks?

• A. Relief valves and gate valves
• B. Shutoff valves and bleed valves
• C. Check valves and control valves
• D. Flow valves and pressure valves

Answer: (C)

Check valves and control valves are the two types typically used in fuel tanks. A check valve is a one-way device that allows fuel to flow toward the engine but prevents it from flowing backward into the tank, which helps maintain forward flow and prevents siphoning when pumps are off or when multiple tanks are connected. A control valve, on the other hand, regulates and isolates fuel flow—it's what the fuel management system uses to modulate how much fuel leaves the tank and to which engine or transfer path, ensuring the engine receives the right amount and that tanks can be isolated as needed.

The other options describe valves with different primary roles (safety relief, general shutoff, bleeding/venting, or basic flow control) that aren’t the standard pair described for fuel-tank applications.