Definition
A one-way fluid valve that uses a hinged or sliding gate to allow flow in the intended direction and to block flow in the opposite direction. When fluid moves the correct way, pressure pushes the gate open; when flow tries to reverse, the gate swings or slides closed against a seat and seals the line.
Plain English
A valve that lets fluid pass one way only. A small flat door inside swings open when the flow is going the right way and shuts when the flow tries to go backwards.
Context Anchor
Seen in aircraft fuel, oil, hydraulic, and air system descriptions, especially in maintenance manuals and system diagrams.
Derivation
‘Gate’ describes the moving part inside — a flat piece that acts like a door or barrier across the flow path. ‘Check’ here means ‘to stop or restrain,’ as in ‘checking’ unwanted motion. So a gate-type check valve literally uses a gate to stop reverse flow.
Why Pilots Care
Maintains correct flow direction to prevent engine starvation or contamination of upstream components.
Analogy
It works like a one-way swinging door. Push it from the allowed side and it opens; push it from the wrong side and it stays shut.
Intuition Check
Do not read check valve as a valve used for checking or inspecting something. Here, check means stop reverse flow. Do not read gate as an airport gate. Here, gate means the moving door-like part inside the valve.
Example Sentence 1
A gate-type check valve in the fuel line prevents fuel from draining back into the tank when the pump shuts off.
Example Sentence 2
During the system test, pressure confirmed the gate-type check valve closed tightly and prevented any backflow.