Transcript Document
Pressure ? WHAT IS BOYLE’S LAW? • Pressure increases as volume decreases • The typical male can inhale and hold up to 5L of air in his lungs PRESSURE & VOLUME IN THE LUNGS • To measure atm or pressure we use a manometer • While on land, the pressure in a diver’s lungs are at 1 atmosphere of pressure or atm. • If you hold your breath and dive down 33 feet (10 meters) your lungs actually contract in size by a factor of two. They have to -- there is twice as much pressure around the air in your lungs, so they contract. SCUBA DIVING EQUIPMENT • SCUBA diving is different from holding your breath and diving, because a diver’s body experiences increasing pressure differences causing a decrease in lung volume. The air tank contains highly compressed air and as the diver descends, the demand regulator controls air coming out of the tank which has the same pressure as the pressure that the water is exerting. • This diving equipment or SCUBA gear stands for: • Self-Contained Underwater Breathing Apparatus SCUBA DIVING DEPTHS • Certified recreational divers maximum depth is often set at 130 ft deep, however most diving takes place less than 100 ft deep. (epipelagic zone) • Diving deeper than 130 ft requires decompression dive training. Depth Zones COMMERCIAL DIVING SUITS "Neufeldt-Kuhnke" diving suit, 1923 •Used in deep waters •Shell resists pressure up to a depth of 160 meters •Telephone lets the diver stay in contact with the surface •The grips serving as hands are mobile enough to accomplishment exacting tasks Atmospheric Hardsuit •Protect divers from pressure maintained enough dexterity to carry out work. •Operate at normal pressure- the diver can descend and ascend without long decompression stops •Can operate at depths of 1000 feet for up to six hours. DIVING SUITS AND INDUSTRY Uses of Commerical Diving Suits •Underwater inspection and non-destructive testing •Repairs of underwater structures •Marine salvage •All marine operations that require deep diving and/or long bottom times •Rescue capacity for submersible operations •Platform inspections •Pipeline surveys Industries that Require the Use of Hard-Hat Divers •Scientific research • Underwater construction and repair • Off shore oil industries • Salvage or recovery PRESSURE ILLNESSES • Barotrama (aka “The Squeezes”) • Pulmonary Barotrauma • Mask Barotrauma • Ear and Sinus Barotrauma • Decompression Sickness (aka “The Bends”) • Air Embolism • Nitrogen Narcosis • Oxygen Toxicity BAROTRAUMA – AKA “THE SQUEEZES” • Barotrauma refers to medical problems that arise from the pressure differences between areas of the body and the environment and is a particular concern for scuba divers. • Greater pressures under water compress airfilled spaces in the body such as: • Lungs • middle ear • eustachian tube to throat • nasal sinuses FORMS OF BAROTRAMAS Forms of Barotrama • Pulmonary Barotrauma • Mask Barotrauma • Ear, Sinus Barotrauma Technique Divers use to equalize the air pressure inside the throat and ears to avoid pain and damage is • Pulmonary barotrauma - Ascending slowly and breathing during ascent • Mask barotrauma - Blow out air from the nose into the face mask • Sinus and ear barotrauma - Yawn or swallow with nostrils pinched BAROTRAUMA IN FISH • Fish have a swim bladder - a gas-filled organ that regulates their buoyancy. When fish are brought up from depth, decreasing pressure allows the gas to expand which may cause injury and gas expansion - swollen and tight belly, stomach protruding past the gullet and into the mouth, and distended and/or "crystallized" eyes. • Swim bladder disease - causes fish to swim disorientated and flip over. Common in aquarium fish. Most commonly caused by high nitrate level in over feeding AIR IS A MIXTURE, BESIDES OXYGEN, WHAT OTHER GAS DISSOLVES INTO TISSUES? DECOMPRESSION SICKNESS AKA “THE BENDS” • Related more to Henry's Law, which states that more gas will be dissolved in a liquid when the gas is pressurized. As a diver descends, nitrogen gas is compressed and dissolved in the tissues. Rising too quickly results in rapid decompression of the gases (bubbling), causing distension and damage to tissues which can be very painful. • Six factors that can cause decompression sickness. 1. Stay down too long 2. Dive too deep 3. Come up too fast 4. Make too many dives in too short a time. 5. Exercise heavily during the dive 6. Travel to altitudes above 2,500 meters too soon after diving RATE OF ASCENT/AIR EMBOLISM • What is the safe rate of ascent for divers to avoid decompression sickness? • 0.3 to 1 meter per second (about the rate at which a bubble rises) If a diver ascends too quickly, nitrogen gas bubbles will form in body tissue rather than being exhaled. • Air Embolism • While scuba diving, gas bubbles can enter the circulatory system through small ruptured veins in the lungs. These bubbles can pass through the heart to obstruct blood flow in the arteries of the brain or heart. • This most commonly occurs when a diver ascends rapidly because of air shortage or panic NITROGEN NARCOSIS • Nitrogen narcosis is an altered state of awareness caused by breathing a high partial pressure (or concentration) of nitrogen. The deeper a diver goes, the greater the partial pressure of nitrogen, and the stronger the diver's narcosis will be. • When nitrogen gas enters the blood, and saturates the body tissue, it will cause symptoms similar to the effects of intoxication (reaction time & impaired judgment). • In order to release the nitrogen slowly from the body, a diver must ascend slowly and carry out decompression stops if necessary - this allows the nitrogen to slowly seep out of the body tissues and either immediately revert to being a gas or to become tiny harmless bubbles which will eventually become revert to gas.