Diode

Diode

The diode is a one-way valve. It only lets air flow through in one direction. The flow of direction is from the clear tube to the black tube. You can compare this to the black ring often found on diodes in electronics, which indicates the cathode.

Diodes are often used to:

  • Prevent air from escaping, but allow it to flow in, for example in applications where a hand pump is used for inflation
  • Protection against backflow

How does it work?

Inside the clear tube of the diode a duckbill valve is embedded. The duckbill valve only opens one way. When air comes in from the top, the two flaps of the bill are pushed apart by the air pressure, and air can flow down. However, when air comes in from the bottom, black tube, the two flaps of the bill are pressed firmly together, and the air can’t pass.

Symbol

Schematic symbol of a diode, or check valve. Input on the left, output on the right.