A PRESENTATION ON PERILS OF DEEP SEA DIVING

BY

ABHISHEK KUMAR

Scuba: acronym for self contained underwater breathing apparatus.

Scuba Diving : form of underwater diving in which a diver uses a scuba set to breathe underwater.

TYPES OF SCUBA DIVING

•Personal

•Professional

PERSONAL

• cave diving

• wreck diving

• ice diving

• deep diving

PROFESSIONAL

• Military Diving

1. Direct Combat

2. Infiltration behind enemy lines

3. Placing mines

4. Engineering operations

5. Civilian operations

6. Rescue operations

EQUIPMENTS

TERMS CONTD..

night.

MECHANISM

Diving suits made of compressible materials, decrease in volume as the diver descends, and expand again as the diver ascends, creating buoyancy changes.

The diver can inject air into dry suits to counteract the compression effect and squeeze.

Buoyancy compensators allow easy and fine adjustments in the diver's overall volume and therefore buoyancy.

HAZARDS & DANGERS

Weight of the water column above the diver causes an increase in pressure in proportion to depth.

Variation of pressure with depth cause compressible materials and gas filled spaces to tend to change volume, which can cause the surrounding material or tissues to be stressed, with the risk of injury if the stress gets too high.

HAZARDS & DANGERS contd..

• Pressure injuries are called barotrauma and can be quite painful, even potentially fatal - in severe cases causing a ruptured lung, eardrum or damage to the sinuses.

Increased amounts of non-metabolic gases(usually nitrogen and/or helium) dissolving in the bloodstream will accumulate until saturated.

HAZARDS & DANGERS contd..

When the pressure is reduced during ascent, the amount of dissolved inert gas that can be held in stable solution in the tissues is reduced

The dissolved gas will be diffused back from the bloodstream to the gas in the lungs and exhaled stable solution in the tissues is reduced.

The reduced gas concentration in the blood has a similar effect when it passes through tissues carrying a higher concentration, and that gas will diffuse back into the bloodstream, reducing the loading of the tissues.

HAZARDS & DANGERS contd..

Reversible alteration in consciousness producing a state similar to alcohol intoxication in divers who breathe high pressure gas at depth.

Cause: toxic effect of high nitrogen pressure on nerve conduction.

Mechanism similar to anaesthesia and can be feel at a depth of 40m.

Symptoms: Euphoria, anxiety, loss of coordination and lack of concentration.

HAZARDS & DANGERS contd..

occurs when oxygen in the body exceeds a safe partial pressure

result in the diver spitting out his regulator and drowning

Effects: cough, pneumonia, permanent lung damage, muscular twitching, vomiting, dizziness, vision or hearing abnormalities.

For deep dives—generally past 180 feet (55 m), divers use "hypoxic blends" containing a lower percentage of oxygen than atmospheric air.

SUBMERSIBLES• small vehicle having shorter range(10km below the surface)

designed to operate underwater.• supported by a surface vessel, platform, shore team or

sometimes a larger submarine.• hold only a small crew, and have no living facilities.

Technologies involved in design:

Single atmosphere submersibles:

• contains pressurized hull & occupants are at standard atmospheric pressure.

Ambient pressure technology: • maintains the same pressure both inside and outside the

vessel. This reduces the pressure that the hull has to withstand.

Wet Sub Technology:

• refers to a vehicle that may or may not be enclosed, but in either case water floods the interior

• SCUBA equipment is used to facilitate breathing.

Deep-diving manned submersibles:

• Bathyscaphe Trieste reach the deepest part of the ocean(nearly 11km)below the surface, at the bottom of the Mariana Trench in 1960.

• China(Jiaolong project in 2002)The Jialong submersible was designed to reach depths of up to 7,000 meters below sea level and is expected to have a 7,000-meter test dive in 2012.

• DSV Alvin, which takes 3 people to depths of up to 4,500 metres(14,800 ft).

Commercial submersibles

• small submersibles for tourism, exploration and adventure travel.

ROVs

• Small unmanned submersibles called "marine remotely operated vehicles" or MROVs

• Used to work in water too deep or too dangerous for divers.• Remotely operated vehicles (ROVs) repair offshore oil platforms• The wreck of the Titanic was explored by such a vehicle, as well as by

a manned vessel.

SUBMARINES• A submarine(large crewed autonomous vessel) is a watercraft capable of independent

operation underwater. • It differs from a submersible, which has more limited underwater capability.

MECHANISM

• Weight of water displaced is equal to the weight of the ship. This displacement of water creates an upward force called the buoyant force and acts opposite to gravity .

• Unlike a ship, a submarine can control its buoyancy, thus allowing it to sink and surface at will.

Controlling buoyancy The submarine has ballast tanks and auxiliary, or trim tanks, that can be alternately filled with water or air (see animation below). When the submarine is on the surface, the ballast tanks are filled with air and the submarine's overall density is less than that of the surrounding water. As the submarine dives, the ballast tanks are flooded with water and the air in the ballast tanks is vented from the submarine until its overall density is greater than the surrounding water and the submarine begins to sink (negative buoyancy). A supply of compressed air is maintained aboard the submarine in air flasks for life support and for use with the ballast tanks.

MANOUVERINGHydroplanes:

• movable sets of short "wings" called hydroplanes on the stern (back) that control the angle of the dive.

• Angled so that water moves over the stern, which forces the stern upward; therefore, the submarine is angled downward.

Life supportMaintaining the Air QualityA submarine is a sealed container that contains people and a limited supply of air.• Oxygen is supplied either from pressurized tanks(oxygen generator

or some sort of "oxygen canister" )that releases oxygen by a very hot chemical reaction.

• Carbon dioxide can be removed from the air chemically using soda lime (sodium hydroxide and calcium hydroxide) in devices called scrubbers.

• The moisture can be removed by a dehumidifier or by chemicals. • Filters are used to remove particulates, dirt and dust from the air.

Maintaining a Fresh Water Supply• Distillation apparatus that can take in seawater and produce fresh water. • Water is used mainly for cooling electronic equipment and for supporting the crew.

Maintaining Temperature• Electrically heated to maintain a comfortable temperature for the crew. • Electrical power for the heaters comes from the nuclear reactor, diesel engine, or batteries

(emergency).

Navigation• Equipped with navigational charts and sophisticated navigational equipment. • Underwater, the submarine uses inertial guidance systems (electric or mechanical) • The inertial guidance systems are accurate to 150 hours of operation and must be realigned

by other surface-dependent navigational systems (GPS, radio, radar, satellite). • Range of operation is within a hundred feet of its intended course.• To locate a target, a submarine uses active and passive SONAR (sound navigation and

ranging).