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1. Opening the scuba cylinder releases high-pressure air into the regulator first stage—an automatic demand valve that responds to changes in pressure. 

2. On the inside of the first stage, air pressure from the cylinder works against a spring to close the first-stage valve. On the outside, ambient pressure also works with the same spring, trying to open the first-stage valve. As long as the tank pressure is greater, the valve remains closed until you inhale. 

3. When you inhale, a flexible diaphragm in the second stage is pulled in, pressing on a lever attached to a spring. The spring compresses and opens the second stage demand valve, allowing air to flow through the system. 

4. As air rushes out of the hose to fill the second stage and your mouth and lungs, it creates a partial vacuum in the hose. Air pressure pushes through the first stage demand valve to fill the hose and in turn the second stage. Air flows as long as there is a demand—the suction that causes the vacuum. When you stop inhaling, the hose and then the first stage refill with air and restabilize. 

5. When there is no demand on the regulator, it is filled with air and there is no flow. 

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Regulator Maintenance

Regulator must be serviced by a trained technician at least once a year. If you use your regulator extensively or commercially, it should be serviced every six months or every 50 dives. This will entail bringing in your warranty in order to save money on parts and in some instances, labour (which is seldom included in the warranty). Sharky's services all makes and models of regulators. 

A competent inspection will usually reveal whether or not the regulator is in need of an overhaul or a simple cleaning or tune-up. No amount of washing or careful use can entirely prevent your regulator from becoming out of tune. A simple tune-up will usually involve adjusting the first stage valve to the correct intermediate pressure, along with perhaps a second stage adjustment as well.

Cleaning
The most important maintenance procedure you can perform on your regulator is a complete, fresh water rinse immediately after, or within a few hours of your last dive. Even if you don't have a chance to rinse off your other equipment right away, try to see that your regulator gets a fresh water rinse as soon as possible, regardless of whether you have been diving in salt or fresh water. 

If allowed to remain inside your regulator, dried salt crystals and sand particles can damage the precision parts inside. the chlorine and acids in swimming pools, as well as the mineral and alkaline deposits present in fresh water lakes and rivers can also cause corrosion and damage to many regulator components. 

To properly rinse a regulator:

1. Make sure the dust cap is securely in place on the first stage air inlet and that it has a watertight seal. 
 

2. Use warm (not hot) water to rinse or soak your regulator. This will dissolve any dried salt crystals that may have accumulated in the interior. 
 

3. Direct a low pressure stream of fresh water over the first stage, and allow it to run freely through any open ports. If your first stage uses a piston-type valve, pay attention to rinsing all salt and sand out of the water chamber, as sand particles or salt build-up can interfere with the operation of the piston by causing damage to the piston o-ring. 
 

4. Rinse the second stage by directing a stream of fresh water into the mouthpiece and allowing it to exit through the exhaust tee. Flush water around and outside of the entire second stage, concentrating on the swivels, and LP and HP cracks and crevices. Do not push the purge button, unless you are holding the hose and first stage high above the second stage and away from the water, or unless the regulator is pressurized on the tank. 
 

5. Another option is to immerse the entire assembly in a tub of warm water, always ensuring that the watertight dust cap is securely in place. This would be advisable if a period of time has lapsed after your dive without rinsing the regulator. Allow the regulator to soak for five to ten minutes, sloshing it around to loosen any stubborn particles. 
 

6. The purge button should never be pushed while the regulator is completely immersed in water. This opens the second stage valve, allowing water to flow through the hose and back into the interior of the first stage assembly. Remove the yoke screw and rinse the yoke and screw threads while holding the dust cap in place. After rinsing, lubricate lightly with silicone spray. 
 

7. Allow the regulator to dry thoroughly before storing it. Always dry it away from direct sunlight to protect the rubber parts.