Master Diver Certification Essay
Open circuit demand scuba is the most commonly used by recreational divers, but closed circuit and semi-closed rebreathers are now available.
Test Pressure: the pressure to which the cylinder is subjected to during hydrostatic testing. For a 200 bar cylinder it is 300 bars, for a 232 bar cylinder it is 348 bars.
If internal inspection reveals corrosion, it may have to be cleaned by tumbling. The tumbling process involves filling the cylinder approximately half full of an abrasive material such as carbide chips, or aluminum oxide chips, and rotating it for a number of hours.
A dual valve for a single cylinder, known as a Y-valve, or an H-valve, allows a diver to mount 2 regulator systems on …show more content…
The moon, being much closer to the earth, influences the tides about twice as much as the sun, despite its relatively small size.
When spring tides coincide with a perigee, the highest tides of the year are produced, and when a neap tides coincides with an apogee, the lowest tides of the year are produced.
Spring Tides – when tides are higher than normal during new and full moons
Neap Tides – when tides are lower than normal during times the sun and moon are out of phase
Perigee – when the moon is in orbit nearest the earth
Apogee – when moon is in orbit furthest from the earth
Diurnal (daily) – One high tide and one low tide occurring every 24 hours and 50 minutes (time required for the moon to pass to a fixed point on the earth twice).
Semi-Diurnal (twice daily) – Two high and two low tides of approximately equal height every 24 hours and 50 minutes. A tidal change occurs approximately every six hours.
Seiches are waves that occur when the surface of a large, partially enclosed body of water is disturbed, long waves may be established which rhythmically oscillate as they reflect from opposite ends of the basin. They have a period that depends on the size and depth of the basin.
Longshore Current - Waves approaching shore at an angle cause a current system that flows parallel to shore.
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