valve
A valve is a device that controls the flow of liquid, gas, or air.
- An open valve allows liquid, gas, or air to move through pipes easily.
- When the valve is closed, nothing flows through.
- Valves are found on industrial equipment, in factories and plants.
- The valves on a trumpet are controlled by a musician who blows air through the instrument to create different sounds.
- There are valves in your heart that control the flow of blood. These are called pulmonary valves.