Page 231

19116TC

219 MDT: Maximum Dive Time. Med iastinal Emphysema: The condition that exists when air from a lung overexpansion injury escapes into the chest area near the heart. Mid dle Ear: The space in the ear containing the auditory bones. It opens into the throat through the Eustachian tube. Mul tilevel Dive: A dive involving periods of time at different depths. N NAU I: National Association of Underwater Instructors. Also called NAUI Worldwide. Neg ative Buoyancy: The state that exists when an object sinks. Actually a contradiction in terms. Buoyancy is positive by definition. Neu tral Buoyancy: The state that exists when an object neither floats nor sinks. Nit rogen: The gas that forms 78% of the atmosphere. It is metabolically inert but is the gas that causes decompression sickness and nitrogen narcosis. Nit rogen Narcosis: The name given to the disorienting effect nitrogen has on the brain at increased pressure. O Oct opus Regulator: An extra second stage attached to the regulator for use in out of air situations. One Atmosphere: The force of the atmosphere at sea level on the earth taken as a constant, equal to 14.7 pounds per square inch, or approximately 1 bar. Ove rexpansion Injury: An injury caused by the expansion of air rupturing enclosed body spaces. Ove rpressure Valve: An device built into buoyancy compensators, which allows the escape of excess air without damage to the buoyancy compensator. GLOSSARY Oxy gen: The gas that is necessary to sustain life. Oxygen makes up approximately 20.9% of the air. P Pne umothorax: The condition that exists when air from an overexpansion injury escapes into a pleural cavity. Pos itive Buoyancy: The state that exists when an object floats or rises in water. Actually a redundancy, as buoyancy is always a positive (upward) force. Pre cautionary Decompression Stop: A period of three to five minutes spent at a depth of 5 meters (15 feet) as a safety precaution even though the Maximum Dive Time has not been exceeded. Pre ssure: The application of force. In diving used for the force of the weight of the air and water above a diver measured in bar or pounds per square inch. Pre ssure Gauge: A piece of equipment that allows one to measure the pressure of air in a scuba cylinder. Pre ssure Relief Disk: A thin piece of metal placed in cylinder valves, that ruptures to prevent pressure from reaching dangerous levels. Also called a burst disk. It is a one-time use device that must be replaced if it bursts. PSI: Pounds per square inch. Q Qui ck Release Buckle: A buckle designed to be operated with one hand so it can be opened quickly in an emergency. R Rap ture of the Deep: An older, quaint term for nitrogen narcosis. Ref erence Line: The lubber line on a compass. The stationary line that shows the direction of travel. GLOSSARY


19116TC
To see the actual publication please follow the link above