Which of these valves allows both fuel and air to be vented overboard?

The correct answer is the sniffle valve because its primary function is to allow venting of both fuel and air in a controlled manner, particularly in systems where fuel can expand due to temperature changes or pressure fluctuations. Sniffle valves are typically designed to open when the internal pressure of a tank exceeds a certain threshold, allowing excess fuel vapors and air to escape, and then to close again when the pressure falls back to a safe level. This feature not only helps maintain system pressure but also prevents leakage of fuel, contributing to safety and environmental protection.

In contrast, float check valves are primarily used to prevent backflow of liquid by relying on the presence of a float that moves with the liquid level. They are not designed for venting purposes.

Pressure relief valves are intended to release pressure within a system that exceeds a set limit, but their function is more focused on relieving excess pressure rather than allowing for the venting of both fuel and air in tandem.

Level control shutoff valves are designed to stop the flow of liquids when a certain level is reached, but they do not function to vent air and fuel together. Their primary role is to manage liquid levels within a system instead of venting gases.

In summary, sniffle valves are specifically suited