Equipment Flashcards
Which are cylinder markings that denote the type of metal
A) 3AL
B) 3AC
C) 3AA
D) 3A
E) 67432
A, C, D
What type of cylinder is 3AA
Chrome molybdenum steel
What type of cylinder is 3AL
Aluminum
What type of cylinder is 3A
Older carbon steel that is more prone to corrosion
Which is the hydrostatic test date
A) 2750
B) 8$20
C) 53927
D) 11@91
B and D
How often is the hydrostatic test required
Every 5 years
What is the + sign mean after the hydrostatic test date, what type of cylinders does it appear on steel and/or aluminum?
Can be filled 10% over working pressure
Steel only
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?
70/2500 = .028 cubic feet psi steel
.028 * 2000 = 56
80/3000 =.027 cubic feet psi aluminum
.027*2000 = 54
Steel has more air
Aluminum cylinders were introduced because they have a higher working pressure and is stronger? T/F
False - less corrosion, not it’s strength
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
C D
Which enables use of much higher air pressures the DIN/Yoke
DIN
Is the O ring deeper/shallower in the cylinder valve and more/less stable in the DIN valve
Deeper more
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.
Burst disk
Valve
140%
If a burst disk were to rupture while on a divers back, which way would the force be directed
Away from the wearer’s head
What could happen if you inserted a disk for an aluminum cylinder in a steel cylinder and the cylinder was overpressurized.
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!
You only need to replace the burst disk after it ruptured? T/F
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
does a burst disk vent to straight out/ to the sides?
Why
To the sides
To prevent cylinder from spinning
It is okay to use heat treatment to refinish or paint a scuba cylinder? T/F
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
A cylinder should be ____ _____ anytime it is exposed to temperatures above ____ degrees to confirm its structural integrity
Hydrostaticly tested
180 degrees
A cylinder should be destroyed after 20 years? T/F
False
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
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
If during a hydrostatic test a cylinder does not compress down to a size close to its original size that’s okay? T/F
False - it is condemned
During a hydrostatic test a cylinder is filled to what pressure of its working pressure
5/3
What pressure would you hydrostaticly test a cylinder with a working pressure of 2900
5/3 = 1.67
1.67* 2900 = 4,843
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
B, C, E
Red or green accumulation on the first stage regulator could mean there is a significant amount of _____ or _____ _____ within the cyclinder
Corrosion
Foreign Material
Loose material inside the cylinder could cause what problem
The valve to clog or some other problem
Should cylinders used extensively in seawater be inspected more often than annually? Y/N
Yes
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
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
The term open circuit refers to the _____ air is released directly into the _____
Exhaled
Water
A closed circuit scuba system exhales air into the water? T/F
False - it is captured, filtered, reoxygenated and returned to the diver to be re-breathed
The demand valve refers to the fact that the regulator will provide air only upon ____.
Inhalation (aka on diver’s demand)
What does the demand valve on a regulator during exhalation
Closes and air flow is terminated
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
All except A
Function of first stage SCUBA regulator is to provide high pressure gas from cylinder to second stage? T/F
False - it reduces the cylinder’s high pressure to an intermediate pressure (85-140psi plus ambient water pressure)
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
The regulator would not be able to deliver air
Approximately 191’ I think
85/.445=191’
As 191*.445 = 84.9
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
True
The ambient pressure in a second stage regulator is sensed by a inflexible piston? T/F
False - flexible diaphragm
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 _____
Valve
Valve
Valve
Maintenance
Fail safe refers to a regulators tendency to ____ _____ because of the use of a _____ valve in the second stage
Free flow
Downstream
A downstream valve means it will tend to close with the flow of air? T/F
False - open
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 ___ ____
Open
Open
Free flow
The primary advantage of the fail safe design, which is a vital safety feature, is that
What happens to the airflow
Air is still delivered to the diver
Airflow is continuous/free flow
It’s okay to continue a dive with a free flowing regulator if the air flow is manageable? Y/N
No
An environmental seal on a first stage regulator does what
Not allow water to contact first stage piston or diaphragm
Without an environmental seal using a first stage regulator on an ice dive could cause it to
Why
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
In environmentally sealed first stage regulators the, what is used in place of water?
Does it freeze at a lower/higher point than water?
Silicone grease or alcohol
Much Lower
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
B C
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 _____
Downstream
Upstream
Ex) if can push a door open to enter a room it is downstream, whereas if pull to open its upstream
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
All
As can provide more air flow to diver as not effected by cylinder pressure therefore easier to breathe
Can a buddy team share a dive computer as long as they use it conservatively ? Y/N
Why
No because both buddies never dive the same profile.
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
Slightly less than 15 minutes, use the more conservative one, and make a safety stop
It’s okay to dive a table or dive computer to its limits? T/F
False because little is known about the decompression phenomenon and individuals vary in their susceptibility, which is why should always make a safety stop.
A capillary depth gauge works by _____ law. It’s an empty open plastic tube that allows water to enter at one end.
Boyle’s
Does a capillary depth gauge have any moving parts? Y/N
No
Do capillary depth gauges have lots of problems? Y/N
Yes
Increasingly small depth increments beyond 66’
Difficulty seeing the rising water column
Air bubbles getting into tube
What are capillary depth gauges typically used for
Backup gauges in shallow water
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
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’
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?
Sealed coil
Coil tighter
Filled with air surrounded by oil
An electronic depth gauge has a transducer that varies its electrical transmission depending on the pressure exerted on it? T/F
True
The least common depth gauge
Capillary
Once more common as a depth gauge but less so today it uses a mechanical _____
Diaphragm
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
B
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
All
Do analog gauges have a wider or narrower range of accuracy
Wider
If you plan a dive to the NDL for a particular depth how could an inaccurate gauge screw you
You could go deeper than what gauge reads putting you in a decompression situation without you knowing
Why is breathing more difficult when deep diving
Because air denser at depth requires more effort to move in and out of lungs therefore more difficult to breathe
When deep diving there should ideally be some form of descent and ascent line? T/F
Why
True
Because site orientation and controlling ascent and descent more difficult
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.
J Valve
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
B
Why would you want to add 10’ to your max depth for a particularly cold and/or strenuous dive
You can be on gassing at a faster rate
The thermal conductivity of argon is approximately 32% lower compared to air? T/F
True
Does a dive computer provide more no deco time? Y/N
Yes
A ____ depth gauge that will give you theoretical depths rather than actual depths when diving at altitude above 1000’
Capillary
Green discoloration on the first stage of a scuba regulator likely means
Water has most likely entered the first stage
What are three types of SPGs
Mechanical
Electronic
Hose-less
What internal valve designs are available on a first stage
Piston
Diaphragm
What is generally accepted as night diving procedures in terms of lights
Have 2 lights a primary and a chemical glow light
If you are doing a deep dive and your computer fails what general guideline should you follow
Ascend to safety stop for as long as possible, possibly as long as air permits
