Title: How Scuba Works | HowStuffWorks
Headings: How Scuba Works
How Scuba Works
Wet Suits, Dry Suits, and Buoyancy Control
Scuba Breathing Apparatus
Diving Physics, Physiology and Hazards
Effects of Scuba Diving on the Body
Scuba: Additional Equipment
Scuba Training
Amateur levels

Content: You inhale, thereby lowering the pressure within the second stage to below the ambient water pressure. The water pressure presses in on the diaphragm membrane and moves the lever. The lever's movement opens the inlet valve. This allows air to flow into the second stage from the first stage, and into your lungs through the mouthpiece. When you exhale, the pressure in the second stage exceeds the ambient water pressure and pushes out on the membrane. The membrane moves away, allowing the lever to return to its normal position and thereby closing the inlet valve. The increased second-stage pressure opens the exhaust valve and allows the exhaled air to leave the second stage. When you inhale again, the exhaust valve closes and the process repeats. Operation of the regulator's second stage
The regulator must be cleaned with freshwater after each dive to eliminate salt water, silt and debris that would prevent the movements of the various valves and membranes and corrode the parts. Regulators should also be serviced at least once per year.