SCUBA Regulator Parts

A properly functioning regulator is the most important piece of equipment for scuba diving, next to a full tank of air. Sometimes referred to as an octopus, even though it only has four "arms," a regulator is required to have five components by PADI, one of several internationally recognized diving certification programs. These components are highly customizable and come in several varieties. Everyone should verify that their regulators are functioning properly before heading to a dive site.

  1. First Stage

    • A regulator's first stage connects to the air cylinder valve. The first stage reduces the pressure of the air in the tank and routes it to four different hoses. Other regulator components are at the end of these hoses. The air in a tank is usually around 3,000 psi. A first stage brings that down to about 140 to 150 psi. First stages are constructed out of chrome-plated brass or titanium. There are two different designs: piston, which is better for clearer water, and diaphragm, which is better for murkier water. First stages can be balanced (sending the same pressure at all times) or unbalanced (pressure decreases as the tank pressure decreases).

    Second Stage

    • The second stage of a regulator lowers the pressure of the cylinder air further from the first stage to the pressure of the surrounding water, making it breathable. Second stages can be made out of a number of materials, but they are generally made of brass and/or plastic. Second stages have three main components: a mouthpiece, an exhaust valve and a purge valve. Mouthpieces are placed into the mouth, and there are usually protrusions that divers bite down on to secure the mouthpiece. Exhaust valve types and location vary, but they expel breathed air. Purge valves are usually buttons on the front of the second stage that can quickly be pressed to force air through the second stage. This comes in handy if debris or water finds its way into the second stage.

    Alternate Second Stage

    • In the unfortunate event of a dive emergency, all regulators are required to have an alternate second stage. This can be used by you or your dive partner if something should happen at depth and it is impossible to immediately surface. Due to the risk of decompression sickness, it is necessary to ascend slowly.

    Low Pressure Hose

    • Low pressure hoses attach at the first stage and terminate at the BCD, or buoyancy control device. A BCD allows a diver to float while on the surface, hover at a specific depth or descend at a desirable rate by using a small amount of the cylinder's air. BCDs come in several styles, but they all require a low-pressure hose to inflate them. There is normally a manual inflation hose for a back-up.

    Submersible Pressure Gauge Hose

    • An SPG hose delivers air from the first stage to a submersible pressure gauge. This gauge allows the diver to know how much pressure he has remaining in his tank. Regular attention must be paid to pressure levels. SPGs can be as basic as a dial style gauge. More advanced dive computers are available that compute time remaining at a specific depth based on the amount of air in your tank.