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Dive Theory For IDC > Equipment > Flashcards

Equipment Flashcards

1
Q

Which are cylinder markings that denote the type of metal
A) 3AL
B) 3AC
C) 3AA
D) 3A
E) 67432

A

A, C, D

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2
Q

What type of cylinder is 3AA

A

Chrome molybdenum steel

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3
Q

What type of cylinder is 3AL

A

Aluminum

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4
Q

What type of cylinder is 3A

A

Older carbon steel that is more prone to corrosion

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5
Q

Which is the hydrostatic test date
A) 2750
B) 8$20
C) 53927
D) 11@91

A

B and D

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6
Q

How often is the hydrostatic test required

A

Every 5 years

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7
Q

What is the + sign mean after the hydrostatic test date, what type of cylinders does it appear on steel and/or aluminum?

A

Can be filled 10% over working pressure

Steel only

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8
Q

A steel cylinder whose capacity is 70 cubic feet at 2500 psi and an aluminum cylinder whose capacity is 80 cubic feet at 3000 psi are both filled to 2000 psi, which contains more air?

A

70/2500 = .028 cubic feet psi steel
.028 * 2000 = 56

80/3000 =.027 cubic feet psi aluminum
.027*2000 = 54

Steel has more air

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9
Q

Aluminum cylinders were introduced because they have a higher working pressure and is stronger? T/F

A

False - less corrosion, not it’s strength

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10
Q

Advantages of DIN connector over standard yoke system
A) cheaper
B) easier to use
C) better seal
D) stronger connection
E) less likely to freeze

A

C D

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11
Q

Which enables use of much higher air pressures the DIN/Yoke

A

DIN

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12
Q

Is the O ring deeper/shallower in the cylinder valve and more/less stable in the DIN valve

A

Deeper more

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13
Q

To prevent a cylinder from rupturing due to over pressurization a ____ _____ is installed in the ____ and is designed to rupture when the cylinder pressure rises about ___% of the cylinders rated pressure.

A

Burst disk

Valve

140%

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14
Q

If a burst disk were to rupture while on a divers back, which way would the force be directed

A

Away from the wearer’s head

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15
Q

What could happen if you inserted a disk for an aluminum cylinder in a steel cylinder and the cylinder was overpressurized.

A

Cylinder could explode because a burst disk for an aluminum cylinder does not blow until reaching about 4200psi which is greater than the test pressure of most steel cylinders!

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16
Q

You only need to replace the burst disk after it ruptured? T/F

A

False - should replace annually, as are stressed during filing and emptying, which causes the metal to weaken and it could blow at a far lower pressure

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17
Q

does a burst disk vent to straight out/ to the sides?

Why

A

To the sides

To prevent cylinder from spinning

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18
Q

It is okay to use heat treatment to refinish or paint a scuba cylinder? T/F

A

False - it could weaken the metal if exposed to heat over 180degrees as it makes it more brittle and less able to withstand expansion and contraction and then could rupture when being filled

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19
Q

A cylinder should be ____ _____ anytime it is exposed to temperatures above ____ degrees to confirm its structural integrity

A

Hydrostaticly tested

180 degrees

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20
Q

A cylinder should be destroyed after 20 years? T/F

A

False

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21
Q

During a hydrostatic test a cylinder is placed in a vacuum chamber and the cylinder is filled with air and the amount of contraction is measured by the amount of air displaced

A

It is placed in a water chamber and filled with water (safer, easier, and less expensive to pressurize) and the amount of water displaced measures its expansion, when pressure decreased it is compared to its original size

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22
Q

If during a hydrostatic test a cylinder does not compress down to a size close to its original size that’s okay? T/F

A

False - it is condemned

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23
Q

During a hydrostatic test a cylinder is filled to what pressure of its working pressure

A

5/3

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24
Q

What pressure would you hydrostaticly test a cylinder with a working pressure of 2900

A

5/3 = 1.67
1.67* 2900 = 4,843

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25
Q

Under what circumstances should a cylinder be reinspected
A) if it smells
B) if red or green accumulation is seen on the filter of the first stage regulator
C) if loose material is heard rolling around inside
D) once every 5 years
E) once every year even if in good condition

A

B, C, E

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26
Q

Red or green accumulation on the first stage regulator could mean there is a significant amount of _____ or _____ _____ within the cyclinder

A

Corrosion

Foreign Material

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27
Q

Loose material inside the cylinder could cause what problem

A

The valve to clog or some other problem

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28
Q

Should cylinders used extensively in seawater be inspected more often than annually? Y/N

A

Yes

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29
Q

What do you look for during a visual inspection
A) hydrostatic pressure testing
B) exterior damage
C) interior corrosion
D) galvanic action between cylinder and valve

A

B C D

Exterior damage can weaken the cylinder

Interior corrosion could clog the cylinder, pitting in steel cylinders could weaken it long before a hydro is required

Galvanic action particularly in sea water can cause cylinder thread and valve to seize which means you can’t remove the valve to inspect the cylinder without destroying the threads

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30
Q

The term open circuit refers to the _____ air is released directly into the _____

A

Exhaled
Water

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31
Q

A closed circuit scuba system exhales air into the water? T/F

A

False - it is captured, filtered, reoxygenated and returned to the diver to be re-breathed

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32
Q

The demand valve refers to the fact that the regulator will provide air only upon ____.

A

Inhalation (aka on diver’s demand)

33
Q

What does the demand valve on a regulator during exhalation

A

Closes and air flow is terminated

34
Q

Primary advantages of open circuit demand valve regulator

A) requires no care or maintenance
B) more efficient gas use versus a free flow system
C) helps avoid CO2 buildup by reducing dead air spaces
D) simpler to use than closed circuit systems and less expensive
E) highly reliable
F) easy to breathe
G) if fails almost always fails open

A

All except A

35
Q

Function of first stage SCUBA regulator is to provide high pressure gas from cylinder to second stage? T/F

A

False - it reduces the cylinder’s high pressure to an intermediate pressure (85-140psi plus ambient water pressure)

36
Q

If the first stage regulator could not compensate for the ambient water pressure and only provided intermediate air pressure at 85psi to 140psi than what would happen when the ambient water pressure exceeded 85 psi say

Bonus at what depth would this occur assuming 85psig

A

The regulator would not be able to deliver air

Approximately 191’ I think

85/.445=191’

As 191*.445 = 84.9

37
Q

Function of second stage scuba regulator is to take the intermediate pressure from first stage and break it down to ambient pressure (surrounding water pressure) for diver to breathe? T/F

A

True

38
Q

The ambient pressure in a second stage regulator is sensed by a inflexible piston? T/F

A

False - flexible diaphragm

39
Q

A pilot valve refers to a second stage design that uses a small ____ to open the main second stage ____. Less effort is required to activate the smaller ____ therefore they tend to breathe more responsively.

As they are more sophisticated they require more _____

A

Valve
Valve
Valve

Maintenance

40
Q

Fail safe refers to a regulators tendency to ____ _____ because of the use of a _____ valve in the second stage

A

Free flow
Downstream

41
Q

A downstream valve means it will tend to close with the flow of air? T/F

A

False - open

42
Q

If a problem occurs in the first stage it will open/close allowing the air to escape to the second stage which will also open/close causing the regulator to ___ ____

A

Open
Open
Free flow

43
Q

The primary advantage of the fail safe design, which is a vital safety feature, is that

What happens to the airflow

A

Air is still delivered to the diver

Airflow is continuous/free flow

44
Q

It’s okay to continue a dive with a free flowing regulator if the air flow is manageable? Y/N

A

No

45
Q

An environmental seal on a first stage regulator does what

A

Not allow water to contact first stage piston or diaphragm

46
Q

Without an environmental seal using a first stage regulator on an ice dive could cause it to

Why

A

Freeze up

The high pressure air depressurizing from the cylinder to first stage draws a tremendous amount of heat from the surrounding environment and if water was in contact would freeze valves open

47
Q

In environmentally sealed first stage regulators the, what is used in place of water?

Does it freeze at a lower/higher point than water?

A

Silicone grease or alcohol

Much Lower

48
Q

Advantages of an environmentally sealed first stage regulator
A) protects from sun damage
B) prevents salt, sediment or other contaminants from entering
C) prevents a freeze up
D) encourages better environmental practices

A

B C

49
Q

A valve that tends to open in the direction of the flow is referred to as ____ while a valve that tends to close in the direction of the flow is referred to as _____

A

Downstream
Upstream

Ex) if can push a door open to enter a room it is downstream, whereas if pull to open its upstream

50
Q

Balanced first stage regulators primary advantage over unbalanced is
A) breathe easier at greater depths even at low cylinder pressure
B) provide greater air flow
C) they are better able to supply a second diver breathing from an octopus

A

All

As can provide more air flow to diver as not effected by cylinder pressure therefore easier to breathe

51
Q

Can a buddy team share a dive computer as long as they use it conservatively ? Y/N

Why

A

No because both buddies never dive the same profile.

52
Q

If one buddies dive computer allows 15 minutes of bottom time at 90’ on a repetitive dive and the other allows 20 minutes they should use the

A

Slightly less than 15 minutes, use the more conservative one, and make a safety stop

53
Q

It’s okay to dive a table or dive computer to its limits? T/F

A

False because little is known about the decompression phenomenon and individuals vary in their susceptibility, which is why should always make a safety stop.

54
Q

A capillary depth gauge works by _____ law. It’s an empty open plastic tube that allows water to enter at one end.

A

Boyle’s

55
Q

Does a capillary depth gauge have any moving parts? Y/N

A

No

56
Q

Do capillary depth gauges have lots of problems? Y/N

A

Yes
Increasingly small depth increments beyond 66’
Difficulty seeing the rising water column
Air bubbles getting into tube

57
Q

What are capillary depth gauges typically used for

A

Backup gauges in shallow water

58
Q

On a dive on a mountain lake at 10,000 a diver checks his capillary depth gauge reads 66’ is this accurate in terms of distance to surface? Y/N

Is it reading deeper or shallower

Why

A

No

Reading deeper

It measures a relationship of atmospheres, but at that altitude 1 ata is not sea level it’s only about 10psi instead of 14.7 psi at sea level. Therefore if it measures 3 ata and it is showing 66’ but it is really 20 psig (as it is 10 psi per ata and it is 2 atas under the surface) which if divided by .432 psi per foot should be 46.3’

59
Q

The oil filled depth gauge works by pressure causing a ____ ____ tube to ____ ____

Is the tube filled with oil or air?
Is it surrounded by oil or air?

A

Sealed coil
Coil tighter

Filled with air surrounded by oil

60
Q

An electronic depth gauge has a transducer that varies its electrical transmission depending on the pressure exerted on it? T/F

A

True

61
Q

The least common depth gauge

A

Capillary

62
Q

Once more common as a depth gauge but less so today it uses a mechanical _____

A

Diaphragm

63
Q

Avoiding the max limits of a dive table is wise because in terms of equipment limits
A) dive tables imprecise
B) depth gauges can malfunction or read inaccurately
C) you can get narcosis more easily
D) dive tables are hard to figure out under water

A

B

64
Q

Special considerations in terms of equipment when planning a deep dive
A) diver use air more quickly than at shallower depth
B) breathing is more difficult than at shallower depth
C) diver may have difficulty controlling ascent/descent

A

All

65
Q

Do analog gauges have a wider or narrower range of accuracy

A

Wider

66
Q

If you plan a dive to the NDL for a particular depth how could an inaccurate gauge screw you

A

You could go deeper than what gauge reads putting you in a decompression situation without you knowing

67
Q

Why is breathing more difficult when deep diving

A

Because air denser at depth requires more effort to move in and out of lungs therefore more difficult to breathe

68
Q

When deep diving there should ideally be some form of descent and ascent line? T/F

Why

A

True

Because site orientation and controlling ascent and descent more difficult

69
Q

The ____ ____ was designed to warn the diver that he has run low on air. When air was running low the reduced pressure enabled a spring mechanism to begin shutting off air flow. By pulling a lever down the mechanism released and normal air flow was restored.

A

J Valve

70
Q

A DIN connection on a scuba cylinder allows the DIN regulator to be screwed directly into the cylinder valve has these advantages:
A) Better air flow and more reliable
B) Better seal between the cylinder and regulator and a stronger connection
C) Less likely to freeze and easier to maintain

A

B

71
Q

Why would you want to add 10’ to your max depth for a particularly cold and/or strenuous dive

A

You can be on gassing at a faster rate

72
Q

The thermal conductivity of argon is approximately 32% lower compared to air? T/F

A

True

73
Q

Does a dive computer provide more no deco time? Y/N

A

Yes

74
Q

A ____ depth gauge that will give you theoretical depths rather than actual depths when diving at altitude above 1000’

A

Capillary

75
Q

Green discoloration on the first stage of a scuba regulator likely means

A

Water has most likely entered the first stage

76
Q

What are three types of SPGs

A

Mechanical
Electronic
Hose-less

77
Q

What internal valve designs are available on a first stage

A

Piston
Diaphragm

78
Q

What is generally accepted as night diving procedures in terms of lights

A

Have 2 lights a primary and a chemical glow light

79
Q

If you are doing a deep dive and your computer fails what general guideline should you follow

A

Ascend to safety stop for as long as possible, possibly as long as air permits

Dive Theory For IDC (4 decks)

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