(2024 Exam) USN Dive Man Mixed Gas

Question 1

Bottom time in excess of table?

Answer 1

Contact NEDU. If advise cannot be attained:
1) “D” using :120 schedule for deepest depth attained
2) Shift to O2 @ 40fsw
3) Sur Diver after :30 O2 @ 40fsw.
4) Compress to 60 NTE 100fsw/min
5) Treat on TT6 w/ max extensions

Question 2

Loss of Helium-Oxygen Supply on the Bottom?

Answer 2

1. Shift to (EGS).
2. Abort the dive.
3. Stay on EGS until 90 fsw.
4. At 90 fsw, shift to 50/50 and complete “D” as sched.
5. If the EGS becomes exhausted before 90 fsw is reached, shift the diver to air, complete decompression to 90 fsw, shift the diver to 50/50, and continue the “D” as planned.

Question 3

The minimum oxygen percentage allowed in the mixture is ___% for depths to 200 fsw and ___% for depths in excess of 200 fsw.

Answer 3

to 200fsw- 14%
Excess of 200fsw- 10%

Question 4

Instruments used to measure oxygen content in helium-oxygen mixtures shall be accurate to___%?

Answer 4

0.5 %

Question 5

To what depth are you allowed to abort a mixed gas dive? Are you allowed to make another dive after?

Answer 5

100 fsw and shallower.

Yes, dives aborted deeper than 100fsw may not.

Question 6

What is normal operational limit for SS mixed gas dives?

Answer 6

300fsw for :30.

Question 7

What is the Maximum working limit for SS Mixed Gas Dives?

Answer 7

380fsw.

Question 8

Following a “no-decompression dive” the diver must wait _____hrs before making a second dive.

Answer 8

12 hours

Question 9

Following a decompression dive, the diver must wait ____hrs?

Answer 9

18 hours.

Question 10

A diver should take a one day break after ____ consecutive days of mixed gas diving?

Answer 10

four

Question 11

What is the minnimum manning for SS mixed gas dives for one and two Divers?

Answer 11

One Diver- 12
Two Divers- 14

Question 12

Who is required to be formally trained (NDSTC) Sur Supplied Diver?

Answer 12

Divers, Timekeeper/recorder, Rack operator, Console Operator.

Question 13

What should the O2 % be for mixed gas dives, and what should it be if the bottom mix is below 16%?

Answer 13

EGS % should be the same as bottom mix, if bottom % is less than 16% the EGS % should be 15 to 17%

Question 14

When diving mixed gas in water below ___ degrees F keeping the diver warm is a life support consideration?

Answer 14

40 degrees.

Question 15

Following a no-decompression dive, the diver must wait ___hrs and Following a decompression the diver must wait ____hrs before ascent to altitude.

Answer 15

No”D”-12 hours

D- 24 hours

Question 16

What is the range for bottom mixture?

Answer 16

90% HE 10% O2
60% HE 40% O2

Question 17

The FADS III Mixed Gas System (FMGS) is designed to support mixed gas dive missions to____fsw?

Answer 17

300fsw

Question 18

The maximum oxygen concentration is set so the diver never exceeds an oxygen partial pressure of ___ ata while on the bottom?

Answer 18

1.3 ata

Question 19

If desired, another dive may be performed following a dive aborted ___
fsw and shallower?

Answer 19

100fsw

Question 20

If the divers arrive early at their first stop?

Answer 20

1. Begin timing the first stop when the required travel time has been completed.
2. If the first stop requires a gas shift, initiate the gas shift and ventilation upon arrival at the stop, but begin the stop time only when the required travel time has been completed.

Question 21

Loss of 50 Percent Oxygen Supply During In-Water Decompression?

Answer 21

1) Shift to Air, cont. “D”
2) Shift back to 50/50 if possible, Air time counts as “D” time.
3) If you cannot get 50/50 back, shift to O2 @ 50fsw. Breathe O2 at 50 & 40, do not exceed 16 mins @ 50. Add additional time from 50 to 40fsw stop. SUR D upon comp. of 40fsw stop.

Question 22

First and last step in CNS O2 Tox Nonconvulsive?

Answer 22

First: Up 10ft and shift to air.

Last: after leaving the subsequent shallower stop, return divers to 50/50.

Question 23

Asymptomatic Omitted “D”, stops missed deeper than 50 requiring more than 60 mins?

Answer 23

Compress to depth of dive, NTE 225fsw. Initiate TT8.

Question 24

In water “D” sickness deeper than 30?

Answer 24

*Descend 10fsw.
*1.5 times the stop times.
*Shift to O2 at 40fsw and complete :30 @ 40fsw.
*Sur “D” after 40fsw completion.

Question 25

Is repetitive diving allow during SS Mix gas diving at altitude?

Answer 25

No,
No “D”- 12hr S.I.
“D”- 18hr S.I.