Open Circuit vs Closed Circuit

[ScoobieDooo]

Can someone explain to me what Open Circuit vs Closed Circuit diving IS?

[nickjb]

Very basically open circuit is traditional diving and closed circuit is rebreather diving.

Open circuit. The gas starts in your tank, through the hose, into your lungs then out into the sea. There is no loop so it is 'open circuit'

Closed circuit. The gas starts in the counter lung, goes though a hose into your lungs then when you breath out it goes back into the counter lungs, via a scrubber to remove the CO2, ready to be breathed again. Most of the gas travels round and round in a loop so it is 'closed circuit'

I'm sure someone will be along soon to explain it better.:)

[ScoobieDooo]

nickjb,
Sounds good enough for me...thanks.

[roakey]

To confuse things there's also semi-closed as well as an oxygen rebreather, which is a simple case of a closed circuit rebreather.

This page does an excellent job of explaining the four types:

http://www.bishopmuseum.org/research/treks/palautz97/rb.html

Roak