Chapter 1- Diving Equipment Diving Equipment 15 cator should prompt you to have the problem corrected and the filter replaced. Leaks from parts of your regulator, or tiny bubbles oozing from hoses under water, require prompt repair by a professional before the leakage becomes more serious. It is common practice to finish a dive with a minor air leak, but the problem should be corrected before the next outing. Have strain reliefs (hose protectors) installed on every hose on your regulator. These sleeves relieve strain on the hoses where they join to metal fittings and prolong their life. You should check underneath them occasionally for wear on the hoses. Secure all regulator attachments while diving. This helps prevent damage to the hoses, attachments, and to the diving environment. Dangling and dragging pressure gauges and extra second stages can easily snag. Many manufacturers require an annual regulator overhaul to keep the regulator covered under warranty. The first and second stage regulators are disassembled, cleaned, and o-rings and seats are replaced. The regulator is then adjusted to factory specifications. Regulator Concerns There are several aspects of scuba regulators that may be of concern to you from time to time. As a NAUI Master Scuba Diver, you should be aware of the following: Water can flow through a regulator if your cylinder is empty. Although you are not supposed to use all of the air in your cylinder, you may inadvertently do so. If this occurs, close the cylinder valve to prevent water from entering your scuba cylinder through the first stage. Regulators can freeze with ice in very cold water. Air is cooled during pressure reduction. When diving in near-freezing (below 4°C 39°F) water, the air flowing through your regulator can further decrease the temperature and cause water in the regulator to freeze. Ice can jam mechanical parts, such as the first stage bias spring and the second stage lever return spring inside your regulator and affect their operation. Some regulators can be “weatherized” to help reduce the possibility of first stage freezing. It is important to exclude moisture in the second stage by being sure it is dry prior to the dive, which will help to keep it from freezing. Air flow may be limited in some regulators at greater depths. Some regulators may not be capable of delivering high flow rates at low cylinder pressures when two divers are breathing from it at the same time in an emergency air sharing situation. Keep this in mind when selecting a regulator and choose one that can meet high demands at low cylinder pressures at the depths you may expect to dive in the future. Regulator performance evaluation has traditionally been based on breathing resistance or effort. This was expressed in terms of centimeters or inches of water pressure exerted by the diver to inhale and exhale through the regulator. For example, 5 and 7 cm (2 and 2.8 in) of water pressure at the surface was the maximum inhalation and exhalation effort, respectively, that was acceptable by US Navy standards. Modern regulator performance is defined in terms of maximum respiratory work level or breathing work. The US Navy defines 0.14 kg-m/l at a depth of 40 meters (132 feet) and a breathing rate of 62.5 RMV (respiratory minute volume in liters per minute) as the maximum acceptable level. Some recreational diving authorities have suggested that this value far exceeds the requirements of the average diver. US Navy regulator test results are frequently available in diving journals. Keep the regulator out of the sand. A single grain of sand can jam the second stage lever and cause a regulator to free flow. To remedy this problem, connect the regulator to a cylinder and pressurize it, submerge it in water, depress the purge button, and rapidly move it back and forth. This might dislodge any sand inside the second stage. When diving in areas where there is considerable sediment in the water, environmentally-sealed first-stage regulators are available that are designed to keep the sediment away from the moving parts inside the regulator. This helps to protect the regulator from excessive wear or malfunction. DIVING INSTRUMENTS
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