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78 Cards in this Set

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  • Back
When diving in tropical waters, what potential danger is often ignored to the divers regret?
Name 5 non-aggressive, but potentially harmful, sea creatures.
Shark, moray eel, sting ray, sea urchin, fire coral, portuguese man-o-war, jelly fish, octopus, barracuda
Give 3 water conditions that would prohibit ocean diving.
Current, tides, visibility, wave, surf, pollution.
Why does the moray eel pose a particular threat to divers gathering lobsters?
The eel and the lobster live in the same holes and crevices. A diver may reach into one of these holes while seeking a lobster and get bit by the eel.
When diving in tropical waters, what procedures would you use to avoid stings and injury from a Portuguese Man-O-War or a jelly fish?
By using your octopus and "blowing" them away. Look up and circle 360 degrees as you ascend to the surface
How would you recognize fire coral and why would you want to avoid it?
Mustard yellow with white tips. Takes on form of various corals, has many stinging cells.
What are 2 ways to avoid injury from a sting ray?
1)Shuffle feet in water when entering a beach area. 2) Do not swim close to bottom.
Explain the proper procedure to follow if caught in a "rip-current".
Inflate your B.C. and ride with the current If possible, swim perpendicular to current until our of it.
What is the danger of touching a stone fish/ scorpion fish?
Their defense is being able to blend into the bottom. Their dorsal spines contain a toxin which can be fatal to humans.
Why would a diver want to make a night dive?
Different forms of life come out to feed, opportunity to see nocturnal animals..
Air is a mixture of several gases. State the two main components and their relative percentages of the mixture.
Oxygen: 20%
Nitrogen: 80%
What is the pressure increase per foot of depth, in psi for: 1)Salt water 2)Fresh Water
S.W. .445 psi/ft
F.W. .432 psi/ft
One half cubic foot of salt water displaced will give a buoyant force of how many pounds? What law is this related to?
(64 lbs/ft cu.)x(.5 ft cu.) = 32 lbs

Related to Archimedes Principle
One half cubic foot of fresh water displaced will give a buoyant force of how many pounds?
(62.4 lbs/ft cu)x(.5 ft cu.) = 31.2 lbs

Archimedes Principle
What is Boyle's Law?
Pressure and Volume are inversely related. As pressure increases, volume decreases, and vice versa...
The pressure at sea level is equal to what? (in psi and in atm)
14.7 psi which equals 1 atm
Describe the difference between absolute pressure and gauge pressure.
Gauge pressure tells the pressure of the surrounding water, absolute pressure includes the 1 atm of pressure from the above air.
What is the #1 rule of scuba diving?
Never Hold Your Breath!
State Henry's Law.
The solubility of a gas in a liquid is almost proportional to the partial pressure of that gas.
How does Henry's Law relate to scuba diving?
At increased depth (and pressure), more Nitrogen from the air goes into solution in the diver's body tissues.
A diver fills his balloon with air from his tank at a depth of 66ft(salt water). What will the volume be when brought to the surface?
V2=(66+33)x 2/(0+33)
V2=99 x 2 / 33
V2=6 ft cu. (1/3 the pressure, 3x the volume)
A diver fills his tank to 3 cubic ft of air in his tank at 99 ft of fresh water. What will the volume be when brought to the surface?
V2=(99+34)x 3/(0+34)
V2=133 x 3 / 34
V2= approx 12 ft cu.(1/4 the pressure, 4x the volume)
What 2 problems can Nitrogen cause when scuba diving?
1) Nitrogen Narcosis
2) Decompression Sickness (the Bends)
What is the sequence of colors to be filtered out as you descend?
(red, orange, yellow, green, blue, indigo, violet)
Why will a diver become chilled in 80 degree water?
Water transfers heat away 25x faster than air. 80 degrees is 18 degrees cooler than our body temp (98.6)
How much larger and closer to objects appear in water?
1/3 (33%) larger, and 25% closer.
Does sound travel faster in air or water? How does it affect a diver?
Travels 4x faster in water. Makes it difficult to distinguish what direction sounds are coming from.
What is the absolute pressure, in psi, at 100 ft of salt water?
P=59.2 psi
What is the absolute pressure, in psi, at 66 ft of fresh water?
P=43.2 psi
What are alveoli and what are their function?
Alveoli are the small sacs found in the lungs where gasses are exchanged between the inhaled air in the sacs and the capillaries surrounding the sacs.
When diving, what is the pressure of the air we breathe from the regulator?
The regulator delivers air to the diver at the ambient water pressure.
What is the function of the Eustachian tube, and why do divers care about it?
It connects the middle ear cavity to the back of the throat. It maintains pressure between the out and middle ear which are separated by the ear drum.
What is squeeze?
The affect of unequalized pressure on any of the body's internal or attached crevices.
What are some examples of parts affected by "squeeze"?
Ear, sinus, thoracic, tooth, intestinal, mask, hood, and suit squeeze.
Will a tank of air last longer at a depth of 30ft or 90ft? Why?
30 ft. It takes almost twice as many air molecules to fill your lungs at 90 ft as at 30 ft. (Boyle's Law)
What is the danger of diving with a head cold?
1) Sinus squeeze
2) Ruptured ear drum
What is the danger of taking decongestants before a dive?
If the decongestant wears off during the dive, you may encounter reverse squeeze, and may not be able to clear ears and/or sinuses on ascent.
Describe two possible ways of rupturing an ear drum.
1) Not clearing the ears during descent.
2) Hood squeeze
How does a diver avoid mask squeeze?
Exhale into mask during the descent in order to equalize pressure between inside of mask and surrounding water.
What should a diver do when he/she encounters ear or sinus squeeze?
Ascend until symptoms disappear, if ears or sinuses don't clear after several attempts to descend, abort dive.
What is the Valsalva Maneuver?
Pinch nose and exhale in order to equalize pressure in ears.
What is the Toynbee Maneuver?
Pinch nose, close mouth and swallow to equalize pressure in ears.
What do you experience when an ear drum blows?
Causes vertigo: disorientation, loss of balance
At 130ft your buddy starts acting funny: a) what do you do? b) what is the name of this problem? c) what is the cause of this problem?
a) Get your buddy to ascend 20-30 ft or until he behaves normally. b) Nitrogen Narcosis. c) Breathing nitrogen at a high partial pressure.
Name 2 ways a scuba diver can incure Oxygen poisoning.
(occurs when breathing Oxygen at a partial pressure above 1.5 atm) 1) compressed air below 218ft. 2) Nitrox below recommended depth 3) oxygen rebreather below 33ft
What is the primary sign of Oxygen poisoning?
What is the danger facing a skin diver who hyperventilates excessively before a deep dive?
Shallow Water Blackout
During a dive, you are working hard and begin to feel anxious and out of breath, a) what do you do, b) What do you think the problem is?
a) slow down and catch your breath. b) carbon dioxide buildup.
When breathing from a new tank, the air has a burnt or oily taste, a) what is the risk of using the tank? b) what could cause this strange taste?
a) carbon monoxide buildup b) dieseling in the compressor, or air inlet to compressor is too close to a source of engine exhaust
What is hypoclycemia? How can it be prevented?
Hypoglycemia is low blood sugar. In scuba, usually result of poor diet. To avoie eat healthy meals before diving.
Descibe symptoms of vertigo and give to possible causes.
Symptoms include spatial disorientation, dizziness, and nausea. Caused by ruptured ear drum, lack of visual reference, and ascent vertigo.
A skin diver fills his lungs to 10 pints, then dives down to 20 ft in the ocean, what is the volume of air in his lungs at 20 ft?
V2=330/53 =approx 6 pints
Calculate partial pressure of Oxygen in 67 ft of salt water. (in psi)
P02 = (D+33) x .445 x .2
P02 = (67+33) x .445 x .2
P02 = 100 x .445 x .2
P02 = .089 psi
A sport diver has developed a case of the bends. What mistake has the diver made?
Stayed too deep for too long.
List 3 things to prevent getting the bends.
Plan dive/dive plan
don't dive too deep
drink plent of fluids before
ascend properly
make a safety stop
What are the primary symptoms of the bends?
Pain in the joints after dive, fatigue, skin itches, dizziness, numbness, tingling, paralysis...
What is the medical treatment for the bends?
Use 100% oxygen with a demand regulator. Then recompression chamber.
A sport diver has developed an air embolism. What mistake did the diver make?
Not properly vented air volume building in lungs. Held breath on ascent.
How could a diver prevent getting an air embolism?
Don't hold breath, breath normally, don't dive if lungs are congested, ascend at 30ft/min or slower.
What are the primary symptoms of an air embolism?
Unconsciousness and/or bloody froth in mouth.
What is the treatment for an air embolism?
100% oxygen on demand regulator, then recompression chamber.
Where are are the bubbles lodged in a diver with a ruptured lung for the followin: a) air embolism, b) subcutaneous emphysema, c) mediastinal emphysema, d) pneumothorax ?
a) brain b)under the skin of the neck and shoulders, c) center of chest cavity surrounding heart, d) between lungs and the walls of the chest cavity
What is the recommended safe rate of ascent for a diver?
30 ft/min or slower.
What are the 2 types of nitrogen narcosis?
warm/clear water: euphoric joyous sensation. cold/low visibility water: melancholy, gloomy, fearful.
What is a major problem of nitrogen narcosis?
Divers indifference to following safety precautions!
What are symptoms of Carbon dioxide excess?
Cyanosis (blue-black discoloration of the skin, lips, nails), rapid breathing, headache, dizziness, vommiting.
How do you prevent carbon dioxide buildup?
Normal deep and continuous breathing. Avoid heavy exercise. If breathing hard, slow and catch breath.
What are the 3 triggers that urge us to breathe?
1) High carbon dioxide level
2) Low partial pressure of oxygen
3) Decreased lung volume.
By law, how often must a SCUBA tank be hydrostatically tested?
Every 5 years
How often must tanks be visually inspected?
Every year
What is the purpose of a "burst disk" in a tank?
Part of the tank valve which will rupture at a certain pressure, safely venting the tank.
Why should you always return from a dive with 500 psi remaining in your tank?
1) safety: it's important to have some reserve, just in case. 2) prevent moisture from getting into the tank.
Why shouldn't you breath a tank dry?
Having some air in tank prevents moisture from getting in.
What is the approximate pressure in the 1st stage of a 2-stage regulator?
140 psi (120-180 psi)
What is the approximate pressure of the 2nd stage of a 2-stage regulator?
The ambient pressure at the 2nd stage.
What is the difference between a "J" valve and a "K" valve?
K = on/off
J = constant pressure reserve (about 300 psi)
What is the purpose of a "dust cap"?
To keep moisture out of the first stage of the regulator.
What information can you obtain from the markings on the neck of a tank?
Date of manufacture, manufacturer, material, serial number, subsequent hydro dates, working pressure