You rely on a regulator to deliver air during your dive, but do you know how your scuba regulator works?

1. GENERAL You can’t breathe directly from a scuba tank because the high-pressure gas would damage your lungs. Hence, the need for a regulator. A reg is made up of the first stage, which reduces gas from high pressure to intermediate pressure, and the second stage, which reduces intermediate pressure to ambient pressure for on-demand delivery to the diver.

2. FIRST STAGE Made from chrome-plated brass and sometimes titanium, the first stage attaches to the cylinder via either a yoke or DIN fitting, and reduces tank pressure from around 3,000 psi to an intermediate pressure at an average of 125 to 145 psi.

3. THE HOSE First and second stages are connected via an interstage hose. These hoses commonly have a rubberized outer layer, but braided hoses have recently become popular because they are lightweight and flexible, and coil easily.

4. MATERIALS Second-stage casings are normally made of thermoplastic polymers, although metal or partial-metal casings are 
not uncommon. Internal hard parts are usually made of stainless steel. Some higher-end models use titanium, which is corrosion-resistant and lightweight.

5. USER CONTROLS The dive/predive switch is useful in preventing free-flows on the surface. The breathing-resistance knob can be used to tune out positive pressure and free-flows caused by current, or modulate work of breathing as depth increases.

More on regulators:

Get an in-depth explanation of how a second stage regulator works.

Get an in-depth explanation of how a first stage regulator works.

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