UDIVE THEORY SAVER – PHYSICS

-Water conducts heat (from our body 20 TIMES) more efficiently than air by CONDUCTION (Radiation-last effect) -The bending of light is called REFACTION Water Absorbs the color and RED disappears first. -Sound travels 4 times faster in water (its denser/thicker than air)and always sounds like its coming from above you -Objects appear to be 33% Larger and 25% closer underwater (Radio4:3) Due to REFRACTION -Visual Reversal is when objects appear to be further away, this is caused by unclear/turbidity (particles) in water

PHYSICS THEORY LAWS

INDEX

Dalton’s

Law

PRESSURE (DENSITY)

AND PARTIAL

PRESSURE OF GASSES

OXYGEN,

NITROGEN, HELIUM,

CARBON DIOXIDE

The sum of all the gases will always equal a whole (100%) As the pressure Increases (Get more), the Partial Pressure (NOT THE PRCENTAGE, THE PERCENTAGE NEVER CHANGES) will increase (Get more). (100% AIR) Will always be 100% no matter what gas mix is used!! 10m = 2 Bar (2 BAR x 0.21) 0.42 oxygen (bar) + (2 BAR x 0.79) 1.58 nitrogen (bar) -------------------- 2.0 BAR 30m = 4 Bar (4 BAR x 0.21) 0.84 oxygen (bar) + (4 BAR x 0.79) 3.16 nitrogen (bar) ------------------------- 4.0 BAR This can be used with any gas mix such as Helium, Nitrogen, and Carbon Dioxide etc… UExample U: Nitrox 36% Oxygen at 20m (3bar) 0.36 x 3 bar =1.08 Bar

Air = 21% Oxygen 79% Nitrogen (ALWAYS) This is important to be able to calculate the partial pressure of gasses to any depth. Doing this you’ll be able to see when Oxygen reaches high levels that my cause oxygen toxicity 1.4 Bar (Max) 1.6 Bar (contingency) Nitrogen levels become narcotic, when it reaches +/- 3 Bar 3 Bar/ (divided by) 0.79 (If using air) = 3.7 Bar = 27m (Ambient)

21% Oxygen + 79% Nitrogen =100% Air OR 0.21 oxygen (bar) 0.79 nitrogen (bar) + ------- 1.0 BAR / 1 ATM (Sea Level)

LAW DIVING

21% O2 79% NITROGEN

Henry’s Law

CASSES AND

LIQUIDS

If the pressure increases (Gets More), the more gas will be dissolved (Go into) the liquid. If the pressure is decreased (gets less), the gas will come out of the liquid. Example: If you shake a Coca Cola bottle, you’re building up pressure inside, forcing the gas in to the cola. When you quickly open the bottle, you decrease the pressure, all the gas comes out the cola, THE BUBBLES! SATURATION: When the pressure (an amount) of gas that has been forced into a liquid, is the same as the surrounding pressure (Outside pressure). Like when shaking a coca cola bottle, you can shake it all you want, until there is no more gas that can be dissolved. It has reached an equal pressure. The pressure is the same from the outside as the pressure inside. SUPERSATURATION: When the pressure become less, the same as when you open the cola bottle, the gas was dissolved into the liquid, starts coming out of the liquid (Out of solution). If it is controlled the bubbles come out slowly. If the pressure is released too fast, the bubbles will come out too fast as well

DECOMPRESS- ION SICCNESS

The longer time a diver spends underwater at a certain depth (under pressure). The more Nitrogen he body absorbs, until saturation is reached-No more nitrogen can be absorbed. If a diver comes up too fast from a dive, pressure is released too fast and the nitrogen will come out too fast and bubbles will form, Causing DECOMPRESSION

SICKNESS

As the temperature increases (Rises) the volume of a flexible container will increase (get bigger) and the pressure inside the container (only a non-flexible) will increase The opposite happens when the temperature deceases (Drops). As the temperature deceases (becomes less), the volume of a flexible container will decrease (get smaller), and the pressure will decreases (becomes less)

FOR EVERY 1 DEGREE CELCIUS CHANGE (UP OR DOWN) IN TEMPERATURE, THERE IS A 0.6 BAR CHANGE IN PRESSURE Less heat, More heat, more volume, more Less the volume, pressure. Air molecules move fast Less the pressure. because it’s so hot, they cause more pressure.

SCUBATANKS

If you leave a full tank outside in the sun, the pressure inside will increase Example: 220 Bar filled at 28 degrees. Will use tank at 3 degree water, what is the pressure change inside the tank? 28-3 degrees = 25 dgr 25x0.6 bar = 15 Bar 220 Bar – 15 Bar = 205 Bar

Charles Law

TEMPERA- TURE AND PRESSURE (DENSITY)

BOLES LAW PRESSURE AND VOLUME

As the pressure surrounding an object increases, the volume will decrease and the density will increase. Gauge Pressure = Water pressure, EXCLUDING atmospheric Pressure (sea water 20m = 2 Bar) Ambient / Absolute Pressure = Atmosphere AND water pressure (sea water 20m = 2 Bar water + 1 Bar atmosphere = 3 Bar) DEPTH ABSOLUTE GAUGE AIR SURFACE VOLUME EXAMPLE PRESSURE PRESSURE VOLUME EQUIVALENT TAKE NOTE OF POINTS U1&2 OF FACTS U!!!!!! UExample: U A flexible container with a volume of 35 liters is at 28m of Ufresh waterU, and is taken to the surface, what will the new volume of the container be? 28m fresh water = 2.7 Bar (28 / U10.3U) Gauge Pressure + 1 Bar for Ambient pressure = 3.7 Bar Volume of the container is 35 liters 35 Liters X 3.7 Bar = U129.5 liters U At the surface UExample continuedU: If you were to take that container back down to 24m of USea Water U, what would the new volume be? 24m Sea Water = 2.4 Bar (24/10) Gauge Pressure + 1 Bar for ambient pressure = 3.4 Bar Volume of container at the surface is 129.5 liters 129.5 Liters / 3.4 Bar = U38 Liters U at 24m

UFACTS

1. 10m OFU SEA WATER U= 1 BAR Example: 34m = 3.4 Bar Ugauge pressureU (34m / U10U = 3.4) + 1 Bar for ambient pressure = 4.4 Bar

2. 10.3m OF UFRESH WATERU = 1 BAR Example: 34m =3.3 Bar Ugauge pressure (34m / U10.3U =3.3) + 1 Bar for Ambient Pressure = 4.3 Bar If you take a container filled with air up from a certain depth. The volume will increase (get bigger) and the air will become less dense (less pressure)

3. You UMultiplyU (X) the volume when taking UUPU.

4. You UDivide U (/) the volume, when taking UDown If you have 2 different depths underwater, FIRST take the volume to the surface and then back down again!!!

Metres

0 1 ATM 0 1 1 10 2 ATM 1 ATM 1/2 2 20 3 ATM 2 ATM 1/3 3 30 4 ATM 3 ATM 1/4 4 40 5 ATM 4 ATM 1/5 5

60 liters

30

20

15

12

Archimedes If an object has either neutral or positive

buoyancy in Sea

water. And you take it to Fresh water.

Buoyancy cannot be

determined without

additional importation

HOWEVER..

If you take an object from

fresh water to sea water. You can

determine the buoyancy of an object

UExample U:

If an object is

neutrally buoyant in

Fresh Water.. It will be positively buoyant in sea water

The Greek mathematician Archimedes determined that “An object wholly or partially immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object.” To determine the buoyancy of an object in water, you need to know: 1. The object’s weight. 2. How much water the object displaces (the object’s volume). 3. The weight of the displaced water. (THE DEPTH OF EITHER SALT/FRESH WATER HAS NO EFFECT TO DETERMINE BUOYANCY OF AN OBJECT) UOPEN U UWATER U U DIVER

O / W - D = ? Objects Sea = 1.03 Displacement Weight OR Fresh = 1.0 UExample #1 U: You Plan to recover a 150kg outboard motor in sea water that displaces 60 liters and lies at 30m.How much air must you put in a lifting device to make the motor neutrally buoyant? Open (O) Object weight = 150 kg Water (W) Water = Sea (1.03 kg) Diver (D) Displacement = 60 Liters DEPTH = MEANS NOTHING!!! 60lt/ (Multiply by) (w) 1.03 (Subtract) – (O) 150kg = 61.8kg – 150kg = 88.2kg (Divide) 88.2kg/1.03=

Answer 85.6ltr UExample #2 U: You must sink into fresh water an object that weight 50 kg. And displaces 300 liters, how much lead weight do you need to affix to the object to make it 10 kg negative on the bottom? (O) 50kg / (w) 1.0 (Fresh) – (D) 300 = -250kg (Positive Buoyant) Object is 250kg positively buoyant. To make it 10kg negative, first make it neutrally buoyant, and then 10kg negatively buoyant. + Add 250kg (to make Neutral) + 10kg more (to make it negative) = 260kg (Answer)

1. An object that weighs less than the water it displaces floats and is positively buoyant. The buoyancy is expressed as a positive number, such as being “two kilograms positive”

2. An object that weighs exactly the same as the water it displaces neither floats nor sinks. It is called neutrally buoyant and adding or removing weight will make it sink or float.

3. An object that weighs more than the water it displaces will sink and is called negatively buoyant. Its buoyancy is expressed as a negative number, such as “two kilograms negative.” REFER TO POINTS 1, 2 & 3 ABOVE FOR MORE INFORMATION TO EXAMPLE #2

1 LITRE OF SEA WATER WEIGHS 1.03 KILOGRAMS 1 LITRE OF FRESH WATER WEIGHS 1.0 KILOGRAMS

UFACTS

1. 10m OF USEA WATER U= 1 BAR UExampleU: 18m =1.8 Bar Ugauge pressureU (18m /10 =1.8) + 1 Bar for Ambient Pressure = 2.8 Bar

2. 10.3m OF UFRESH WATERU = 1 BAR UExample: U18m = 1.75 Bar Ugauge pressureU (18m / 10.3 = 1.75) + 1 Bar for Ambient Pressure = 2.75 Bar

3. You UMultiplyU (X) the volume of air the diver uses when the diver does Down (Deeper)

4. YouU Divide U(/) the volume of air the diver uses when the diver goes UP (Shallower)

1 BAR

2 BAR

3 BAR

4 BAR

5 BAR

AIR CONSUMPTION

Air becomes more dense (more pressure) as you descend underwater. A diver will use more air due to the increased (more) pressure (He’s going deeper…more pressure) A diver will use less air due to the decreased (less) pressure as he ascends. (He’s going up… less pressure) DEPTH AIR VOLMUE Meters 0 1 10 1/2 20 1/3 30 1/4 40 1/5 Example #1: A diver’s air consumption rate is 3 bar per minute at the surface. What will the air density be at 30m compared to the surface, and what will the diver’s air consumption be? Answer: 4 times as dense (30m = 4 Bar) 12 bar/min (3 Bar/min x 4 Bar)

A diver uses 2 Bar/minute at the surface The diver will use 2 x more air at 10m, because the pressure is 2 Bar (The air is 2 x more dense) So he breathes 4 Bar/minute at 10m. At 20m he will use 3 x more air. So he will use 6 Bar/minute at this depth At 30m he will use 4 x more air. He now breathes 8 Bar/ minute. At 40m he will now use 5 x more air. He now breathes 10 Bar/minute

UDIVE THEORY SAVER-PHYSIOLOGY

INDEX DECOMPRESSION SICKNESS (D.O.S)

NITROGEN GAS

EXCHANGE WHAT CAUSES D. C. S ??

Other factors That may Predispose (cause) a diver D.C.S ?

When we breathe, from the lungs our body takes the oxygen and delivers it to the bodies muscles. The body uses oxygen (metabolizes). But the body DOES NOT use Nitrogen for anything. This is what we call an INERT gas Nitrogen is an inert gas Gas exchange between the respiratory and circulatory system occurs between the Alveoli and the pulmonary capillaries. It is here the blood releases carbon dioxide and picks up oxygen

Relating to HENRY’S LAW (If the pressure increases (Get More), the more gas will be dissolved (Go into) the liquid. If the pressure is decreased (gets less), the gas will come out of the liquid.

• The human body is mostly made up of liquids. • Because the body does not use Nitrogen, however under pressure (when

diving) our body is exposed to a higher absorption rate of nitrogen. • The body has to store this nitrogen in the body. • On ascent when diving, the pressure on the body is reduced (Gets less) and

nitrogen in the body has a higher pressure, and has to come out (Super-saturation, like when opening a coca cola bottle after shaking it).

• As long as the nitrogen comes out slowly and is controlled, there is no problem. However, if the pressure is released too fast, the nitrogen will come out too fast.

• This will cause BUBBLES, WHICH CAUSES DECOMPRESSION SICKNESS!!

1. Fat: fat releases nitrogen slowly, more nitrogen in solution after a dive. 2. Age: as we age, our circulatory systems become less efficient. 3. Dehydration: reduces blood in circulation, slowing nitrogen elimination. 4. Injuries/illness: may alter or restrict circulation. 5. Alcohol before or after diving: alters circulation, cause dehydration. 6. Carbon dioxide excess: skip breathing. 7. Cold water: circulation to extremities reduces as dive cools, slowing nitrogen elimination from those areas. 8. Heavy exercise: before, during and after a dive accelerates circulation. 9. Altitude/flying: dive tables/computers are based on surfacing at sea level, thus exposure to lower pressure increases the tissue pressure gradient and may.

INDEX LUNG OVER- EXPANSION INJURES

More than one a these injuries in occur simultaneously CAUSES AIR Embolism Sign & Symptoms

ULung overexpansion injuries are caused: 1. Holding breath during ascent. 2. Diving with a chest cold. 3. Local blockage in the lungs due to loss of surfactant (due to smoking). 4. Expanding air over-expands lungs causing lung rupture.

UAir embolismU: - also called arterial gas embolism (AGE). Air enters bloodstream and flows into arteries. a. Serious and immediately life threatening – bubbles can lodge anywhere, but most common is to flow through the carotid arteries and cause cerebral air embolism. Stops blood flow to the brain. b. Signs and symptoms similar to stroke – dizziness, confusion, shock, paralysis, personality change, unconsciousness and death.

UPneumothorax U –air from rupture goes between lung and chest wall, causing lung to collapse. a. Also serious. Symptoms include chest pain and patient may cough up blood

UMediastinal emphysema U – air from rupture accumulates in center of chest over heart. Pain in the middle (chest) a. Serious because air presses on heart and vessels interfering with circulation. b. Patient may feel faint or short of breath.

USubcutaneous emphysema U – air from rupture accumulates in soft tissues at bases of neck. a. The victim feels fullness in neck and voice may change. The skin may crackle to the touch.

Pneumothorax Sign & Symptoms

Mediastinal Emphysema Sign & Symptoms

Subcutaneous Emphysema Sign & Symptoms

UEARS

3 PARTS

OUTER

MIDDLE

INNER

1. Ossicles connect to cochlea at oval window, which flexes in and out with vibrations. 2. Round window on cochlea flexes out when oval window flexes in to compensate. BAROTRAUMA

EARDRUM RUPTURE

VERTIGO

How the ears and sinuses respond to changing Pressure • Descending, increasing pressure pushes in on ear drum – diver feels as

discomfort. • By equalizing, diver forces air up Eustachian tube to equalize pressure in middle

ear, alleviating the discomfort. • Expanding air normally exits Eustachian tube easily – seldom need to do anything

ascent.

UProblems in Body Air Spaces Barotrauma means “pressure injury”, and results when a body air space isn’t equalized and pressure continues or increases. Middle ear squeeze – caused by Ufailure to equalizeU or inability to equalize due to congestion (diving with a cold). Eardrum rupture – also caused by Ufailure to equalize,U but pressure increases faster than fluids can fill middle ear, Eardrum tears due to pressure. Usually heals without complication, but requires medical attention to prevent infection and permanent damage because water contaminates ear with organic matter and dirt. When the ear drum ruptures,U cold water on vestibular canalsU may cause momentary vertigo – loss of sense of direction and dizziness

APNEA

BRADYCARDIA

CAROTID-

SINUS

REFLEX

UHow the body responds to breath-hold diving, and how you can extendU UBreath-hold time?U *During APNEA (breath holding) the circulatory system uses oxygen stored in the Lungs In cool water, BRADYCARDIA (slowing of the heart) reduces circulation speed, though doesn’t appear to reduce oxygen consumption in humans (it does in marine mammals) * You can increases breath hold time by first hyperventilating (breathing deeply and rapidly) three or four times. Doing so reduces circulatory carbon dioxide so it takes longer to get enough to cause breathing. Too much hyperventilation may lead to shallow water blackout.

• Carotid sinus receptors monitor pressure of arterial blood reaching brain through carotid arteries.

• Low blood pressure triggers a higher heart rate, and high blood pressure triggers a lower heart rate.

• Receptors interpret pressure from an excessively tight hood or wet suit constricting neck as high blood pressure.

• The heart rate slows, reducing blood flow to the brain, but pressure remains, causing yet slower heart rate.

• The diver feels uncomfortable and light-headed, but may lose consciousness if constriction continues unrelieved.

• Avoid by not wearing excessively tight hoods, wet suits or dry suit neck seals.

HYUPER U (HIGH LEVEL)- CAPNIA

Hypercapnia is TOO MUCH carbon dioxide.

• It’s Ucaused by dead air spaceU, skip breathing (holding the breath periodically), shallow raid breathing, overexertion or combination of these. In very rare cases,

air supply may be high in carbon dioxide. • Causes headache and increased breathing. In severe cases, confusion and loss of consciousness. • Avoid by breathing deeply and normally, not skip breathing and by avoiding overexertion.

UDIVE THEORY SAVER- R.D.P

INDEX

THE RECREATIONAL DIVE PLANNER

Different parts of the body absorb and release nitrogen at different rates, blood and muscles absorb nitrogen easier and faster than what fat or bones do. Because of these different TISSUES, a decompression model has what we call UTHEORETICAL TISSUES U OR UCOMPARTMENTS.U Compartments are a way to measure/identify how fast or slow our body (and body tissues) absorb and release nitrogen. FAST COMPARTMENT (Blood & Muscle) = Release and absorb nitrogen fast. SLOW COMPARTMENT (Fat & Bone) = absorb and release nitrogen slow ------------------------------------------------------------------------------------------------------------------ Each compartment has a halftime for the rate at which it absorb and release nitrogen. Halftime is the time, in minutes, for a certain compartment to go halfway from its beginning tissues pressure to saturation(full) at a new depth.

20min Compartment (Modern models range from 3 – 600 and more)

UCompartments?

--------------------------- UHalf Times? Fast (tissue) compartment (Gas washout) = shorter halftime Slow (tissue) compartment (Gas washout) = longer halftime ----------------------- EXAMPLE: A 5 minute halftime compartment will have how much tissue pressure 5 minutes after taken from the surface to 18m of seawater?

3. This (Halfing) can only happen 6 times, the compartment will be considered full (saturated) when it reaches about 98.6%. To make it easy, the tissue pressure is expressed or called *meters* 2. After 20min more, the half from the first 20min half again. 1. After 20mi, the compartment will go half way (Half full).

After 15min 4.5m

After 10min

9m

After 5min

5 minute compartment

18m

2. After 10min the pressure will go halfway again, half remaining 9m. Half of 9m. = 4.5m 1. UANSWER After 5 min, the compartment will go half way. So if this is a 18m compartment, then half of 18m is 9m Answer = 9m of pressure

UValue? The faster the compartment (shorter halftime) the higher the M- value (the more nitrogen it is allowed to have when surfacing); the slower the compartment, the lower the M- value What is the difference between the R.D.P and the US Navy Tables? R.D.P was DEVELOPED IN 1987 and TESTED IN 1988 BY DR RAYMOND E. ROGERS A PADI DIVERMASTER working with D.S.A.T (Diving sciences and technology)

---------------------------------------------------------------------------------------------------------------- URECREATONALU U U.S NAVY TABLES UDIVE PLANNER NO-DECOMPRESSION (NO STOP) STAGE DECOMPRESSION USE 14 COMPARTMENTS 6 COMPARTMENT 60min SURFACE CREDIT 120min SURFACE CREDIT HALFETIMES –Faster gas washout HALFETIMES –Slower gas washout 6 HOURS TO BE CLEAN 12 HOURS TO BE CLEAN OF NITROGEN AFTER A DIVE OF NITROGEN AFTER A DIVE DESIGNED FOR MULTIPLE DESIGNED FOF LIMILTED DIVES A DAY WITH SHORTER DIVES A DAY WITH LONG SURFACE INTERVAL SURFACE INTERVALS (AVERAGE RECREATIONAL DIVER) (MILITARY USE) LONGER BOTTOM TIME ON SHORT BOTTOM TIMES REPETITIVE DIVES ON REPETITVE DIVES Why was the U.S Navy (USN) table at one time the “standard” for recreational diving? The U.S navy tables were developed mainly for military decompression diving, but they became almost the standard in recreational diving until the mid-1980s for several reasons: 1. Before computers, making a table was a difficult process that had to be computed by hand. Few outside the Navy had the information or the ability to produce tables.

2. Many early sport divers began as military dives, bringing the USN tables with them. 3. The USN tables were widely available and public domain, allowing publishers to reproduce and rearrange them.

4. Though they weren’t ideal for recreational dives, they could be relied on when following d i di i i

The M-Value is the maximum tissue pressure (Nitrogen Level) that is allowed to be left in the body after a dive. The M-value shows what does and does not result in D.C.S These M-Value are the A-Z on the R.D.P. (A) being a low level (Low Pressure) of nitrogen, and (Z) being a high level (High Pressure) of nitrogen. At 12m our Halftimes are shorter, so we can have a high M-Value. Example: We can dive at 12m for 147mim = X (M-Value) At 30m our Halftimes are longer, so we have a low M-Value Example: We can dive at 30m for only 20min = N (M-value) The compartment that reaches it’s M-Value first, is called the UCONTROLLING COMPARTMENTU

PRESSURE GROUPS ON THE R.D.P DIVING IN COLD WATER REPETITVE DIVES LIMIT MAXIMUM DEPTHS TO EXPERIENCE LEVELS SPECIAL RULES FOR W, X, Y & Z SURFACING PRESSURE GROUPS SAFETY STOPS IN WATER RECOMPRESSION

UGENERAL RULES FOR USING THE RECREATIONAL U DIVE PANNER

Letters (pressure groups) cannot be swapped (not interchangeable) between the RDP, USN tables or any other tables. You can link pressure groups between different versions of the RDP, such as the wheel and the enriched air 32% and 36% recreation dive planner. When planning a dive in cold water or under conditions that may be strenuous (difficult), plan the dive as though the depth is 4m deeper than actual. Plan repetitive (2PND P OR 3 PRD P) dives so each next dive is to the same, or a shallower depth. Don’t follow a dive with a deeper dive. Plan your deepest dive first. Limit maximum depths in consideration of training and experience. Discover Scuba Diver / Scuba Divers: 12m Open Water Divers: 18m Divers with greater training and experience: 30m (40m is the maximum training depth for Deep Specialty Course). The 42-metre on the Recreational Dive Planner is for emergency purposes only. When planning three or more dives in a day. If the ending pressure group after any dive is W or X, the minimum surface interval between all next dives is 1 hour. If the ending pressure group after any dive is Y or Z, the minimum surface interval between all next dives is 3 hours. Limit following dives to 30 metres/100 feet or shallower. Make a safety stop for 3 minutes at 5m after every dive (recommended).The time at a safely stop need not be added to the bottom time of the dive. Always make a safely stop: A. After any dive to 30m or deeper. B. Any time you will surface within 3 pressure groups of you NDL. C. When a dive is made to any limit (Black Box) of the RDP. * THE GRAY AREA ON YOUR R.D.P DIVE TABLE* In-water recompression – treating DCI by putting the diver back underwater shouldn’t be attempted. Recompression requires a long time, oxygen, and often drug therapy. Normally the required resources aren’t available at a dive site, and incomplete recompression will usually make the dive even worse.

EMERGENCY DECOMPRESSION PROCEDURES DEEPER THAN 40M?? MISSED DECOMPRESSION STOP DIVING AT ALTITUDE FLIGHING AFTER DIVING

An emergency decompression stop for 8 minutes at 5m Umust be made U if a no decompression limit is accidentally exceeded by 5 minutes or less.

• Upon surfacing, the diver must stay out of the water at least 6 hours before making another dive.

If a no decompression limit is exceeded by more than 5 minutes, a 5m decompression stop of no less than 15 minutes is needed (air supply permitting).

• Upon surfacing, the diver must remain out of the water at least 24 hours prior to making another dive.

If you have accidentally go below 40m, immediately ascend (18m per minute) to 5m, and make an emergency decompression stop for 8 minutes. If the no decompression limit for 40m is NOT exceeded by more than 5 minutes. Do not dive again for 6 hours. If you accidentally miss a required decompression stop and have already surfaced and exited the water, remain out of the water, stop diving for 24 hrs and breath pure (100%) oxygen if available. Using the RDP at altitudes 300m above sea level, require the use of special training and procedures. (ADD 4% TO DEPTH FOR EVRY 300m ABOVE SEA LEVEL) – Conversion Table: Page 15 in PADI Adventures in Diving Manual. Wait a minimum surface interval of 12 hours flight if you plan to make daily, multiple repetitive dives for several days, or make dives that need decompression stop, take special care – a surface interval of 18 hours or more before flight is recommended.

UDIVE THEORY SAVER - EQUIPMENT

TANKS UTANK MARKINGS Tanks should always have the following markings 1. Maximum working pressure 2. Maximum capacity 3. Hydrostatic / pressure test date These markings should always be checked before filling. This is important even in different countries with different tank markings

UVISUALS HOW OFTEN?

HOW & WHY?

USTEELU UALMINIUM Have a round base (bottom) Have a square or flat base (bottom) Normal working pressure 220 Bar Normal working pressure 220 Bar UADVANTAGESU U ADVANTAGES USome steel tanksU have a working pressure Aluminum tanks generally last longer of 300 Bar, used for more technical diving and are preferred by dive operators purposes because they are very easy to clean Steel tanks = RUST – difficult It to clean Pressure drops – buoyancy of a diver is Aluminum tanks = ALUMINUM not effected OXIDE (white powder)– easier to clean ALUMINIUM TANK pressure drops – A dive becomes more buoyant and needs to add weight. UVISUAL INPECTION A Visual Inspection testis required by international law to be conducted on all tanks (Steel & Aluminum) ONCE (1) A YEAR. A Visual Inspection is done by looking inside the tank foe any corrosion (Steel Tanks = Rust & Aluminum Tanks = Aluminum Oxide). If there any corrosion, the tanks will be machined and chemically cleaned. If the corrosion has done damage to wall of the tank, the tank will be destroyed. The threading at the neck of the tank (Where the tank valve screws into) is also check for any damage. There was an operator who was filling a tank with the compressor system in a two floor building. While the tank was being filled the tank valve completely shot off the tank. The tank valve went through two floor of the building as well as the roof and landed outside about 40 way. The threading of the tank neck was damaged – good reason for a visual !!!

SCUBA Self Contained Underwater Breathing Apparatus

OPEN CIRCUIT

SEMICLOSED CIRCUIT

REBREATHER Drager Ray/Dolphin

CLOSED CRICUIT

REBREATHER Buddy Inspiration

FROM THE FIRST STAGE

TO THE SECOND

STAGE

Delivers air to the diver at an

AMBIENT/

ABSOLUTE

PRESSURE

UREGULATORS Open circuit scuba – scuba typically used by recreational divers. The diver inhales air from cylinder via a demand valve regulator and exhales it into the water, thus the circuit is open because none of the air is recycled. Though open circuit doesn’t recycle breathing gases, it is the main stay of recreational diving for several reason. a. It’s a much simpler in design, which makes it reliable and less costly. Closed and semi closed systems are more prone to malfunctions. b. It is much easier to learn to use. c. It requires only a cylinder of air. Closed and semi closed units require chemicals and access to pure gases or enriched air. d. It is much simpler to maintain and service. Semi closed circuit rebreathers or SCR – the diver inhales from breathing bag that receives a steady flow of gas (usually enriched air). The diver exhales back into another breathing bag and the gas has carbon dioxide removed chemically before it flows back to the inhalation breathing bag- excess gas from the steady flow trickles out though a valve in the exhalation breathing bag. The circuit is semi-closed because part of the gas is recycled and part of it is released. Closed circuit rebreathers or CCR – the diver inhales from a breathing bag and then exhales back into another breathing bag. The gas has carbon dioxide removed chemically as it moves back to the inhalation bag and electronic sensors dictate a computer (electronically controlled rebreathers) or the diver himself (mechanically controlled rebreathers) to control the flow of oxygen and other gases as required. The circuit is closed because all gas is recycled and none released (except to vent expanding gas on ascent).

UHOW DO OPEN CIRCUIT REGULATORS WORK?

When high Pressure (220Bar) from a tank enters the first stage, the first stage will do two things: 1. It will reduce the high pressure from the rank (220 Bar) to between 9 – 12 Bar. This new pressure is called INTERMEDIATE PRESSURE. 2. The first stage will channel, or guide the Tank pressure to the high pressure hose (Which will go to the pressure gauge, so that the diver can monitor their air pressure). And the Intermediate pressure will go to the second stage and the low pressure inflator hose for the B.C.D

ENVIRONMENTAL

SEAL

UNBALANCED REGULATOR

BALANCED REGULATOR

DEPTH

GAUGES

In very cold water (such as cold water deep diving or ice diving) the temperature drop can cause water to freeze the regulator first stage valves into the open, free flowing position. To avoid free flow in extremely cold water, some regulator first stages have environmental sealing. This seals silicone grease or oil, which don’t freeze, around the first stage. The silicone or oil transmits the pressure from the water to the diaphragm or piston so the regulator operates normally. A regulator designed so that tank air pressure resists or assists (DOES AFFECT) the opening of valves in the first stage is called an unbalanced regulator.

• Breathing will come more difficult as the tank pressure drops. • Breathing is more difficult at greater depths. • Unbalanced regulators are no longer commonly found.

A regulator designed so that tank air pressure neither assists or resists (DOES NOT AFFECT) the opening of valves is called a balanced regulator.

• The ease of breathing is not affected by the tank pressure, even when two dives breath from the same first stage, and inhale and exhale at the same time. Depth is not a concern. • Virtually all modern regulators are balanced regulators.

Capillary depth gauges are a simple piece of clear tubing, sealed at one end and open at the other, based on Boyle’s Law. They are hard to read accurately much deeper than 10m. Best for when diving at altitude. Open bourdon tube gauges contain a spiral shaped tube. Water enters the tube end and increasing pressure causes tube to straighten. The straightening moves the depth gauge needle. Because the tube is open, clogging can be a problem with these devices. Oil-filled gauges also use bourdon tube design, but using a sealed tube in an oil-filled gauge housing. Pressure transmitted through the oil cause the tube to coil more tightly. This moves the depth gauge needle. The depth gauge is not open to the water and therefore not clog prone. Diaphragm gauges function by connecting a flexible diaphragm to a series of levers and gears that move the display needle. Digital gauges are electronic gauges that read depth with a transducer, which varies the electricity it transmits depending on the pressure exerted on it. These provide a digital display. These offer the highest degree of accuracy, and are used in dive computers to the determine depth.

Enriched air divers Upersonally analyzeU the contents of their

cylinders before using them. On some dive boats, the normal practice is to grab any full cylinder available for the next dive – this isn’t appropriate with enriched air, which practice calls for divers to use the tanks they personally analyzed.

UDIVE THEORY SAVER – PHYSICS