Air duct and Schnorchel

Air duct noun - A duct that provides ventilation (as in mines).

Schnorchel and air duct are semantically related. In some cases you can replace term "Schnorchel" with "Air duct", this terms are similar.

Schnorchel noun - Air passage provided by a retractable device containing intake and exhaust pipes; permits a submarine to stay submerged for extended periods of time.

Air duct and schnorchel are semantically related. You can use "Air duct" instead a noun "Schnorchel".