Definition
A component in an aircraft fuel system that removes vapor (gaseous fuel) from the liquid fuel before it reaches the engine, returning the vapor to the fuel tank and allowing only liquid fuel to continue to the carburetor or fuel injection system.
Plain English
A device that separates fuel bubbles from liquid fuel so the engine receives a smooth flow of liquid fuel only.
Context Anchor
Seen in aircraft engine fuel-system descriptions, especially where heat, altitude, or fuel flow problems can let fuel form bubbles before it reaches the engine.
Derivation
From Latin vapor (steam, gaseous form) and separare (to set apart). The name describes exactly what the device does: it sets the vapor apart from the liquid.
Why Pilots Care
It prevents vapor lock, a condition where fuel vapors block liquid flow and cause the engine to lose power or stop, especially in warm conditions.
Analogy
Like a coffee filter that lets liquid through but catches the steam or foam on top.
Grounding Statement
On a hot day or at higher altitude, fuel can form bubbles, and the vapor separator gives those bubbles a place to leave before the fuel reaches the engine.
Intuition Check
A vapor separator is not mainly a dirt filter. It is meant to remove fuel vapor bubbles from liquid fuel, not to strain out solid particles.
Example Sentence 1
On a hot day after shutdown, the vapor separator helps clear gaseous fuel from the lines so the engine restarts smoothly.
Example Sentence 2
Mechanics install vapor separators in high-performance aircraft to maintain reliable fuel delivery during climbs in hot weather.