A regulator system is required to reduce the pressure of the compressed air contained in the cylinder (scuba tank) to an ambient pressure in order to supply breathable air when needed. The regulator system is composed of a pressure reduction device attached directly to the tank – the first stage - and one or more breathing devices attached to the first stage – the second stages.
First stage is made of a:
Divers also connect pressure gauges, BCD inflator hoses, dry suits and other devices to the system.
Breathing device is second stage. The second stage further reduces pressure flowing through the first stage to balance the inhaled air with ambient pressure. The second stage may be: