Air Decompression definitions

Question 1

Descent time

Answer 1

The total elapsed time from the time the diver leaves the surface to the time he reaches bottom. (Rounded to the next whole minute for charting purposes)

Question 2

Bottom time

Answer 2

The total elapsed time from the time the diver leaves the surface to the time he leaves bottom. Bottom time is measured in minutes and round to the next whole minute.

Question 3

Total decompression time

Answer 3

Total elapsed time from time diver leaves bottom to the time he arrives on surface. Also called -TOTAL ASCENT TIME-

Question 4

Total time of dive

Answer 4

Total elapsed time from the time the diver leaves surface to the time he arrives back on surface.

Question 5

Deepest depth

Answer 5

Is the deepest depth recorded on the depth gauge during a dive

Question 6

Maximum depth

Answer 6

The deepest depth obtained by the diver after correction of the depth gauge reading for error.

Question 7

Stage depth

Answer 7

Is the pnuemofathometer reading taken when the divers are on stage just prior to leaving bottom.

Question 8

What is stage depth used for?

Answer 8

Used to compute the distance and travel time to the first stop, or to the surface if no stops are required.

Question 9

Decompression table

Answer 9

Is a structured set of decompression schedules, or limits, usually organized in order of increasing bottomed times and depths.

Question 10

Decompression schedule

Answer 10

a specific decompression procedure for a given combination of depth and bottom time as listed in a decompression table. Normally indicated as feet/minutes.

Question 11

Decompression stop

Answer 11

A specified depth where a diver must remain for a specified length of time (stop time) during ascent.

Question 12

No-decompression (No “D”) Limit

Answer 12

Maximum Time a diver can spend at a given depth and still ascend directly to the surface at the prescribed travel rate without taking decompression stops.

Question 13

No-Decompression dive

Answer 13

A dive that does not require decompression stops

Question 14

Surface interval

Answer 14

In context to repetitive diving, surface interval is the time a diver spends on surface between dives.

In context to SURFACE DECOMPRESSION, total elapsed time from when diver leaves 40 fsw to the time he arrives to 50 fsw on recompression chamber

Question 15

Residual nitrogen

Answer 15

Is the excess nitrogen gas still dissolved in a divers tissues after surfacing. Excess nitrogen is gradually eliminated during surface interval. If second dive is performed before all residual nitrogen has been eliminated, the residual nitrogen must be considered in computing the decompression requirements of the second dive.

Question 16

Single dive

Answer 16

Is any dive conducted after all the residual nitrogen from the prior dives has been eliminated from the tissues.

Question 17

Repetitive dive

Answer 17

Any dive conducted while the diver still has residual nitrogen in tissues from prior dive.

Question 18

Repetitive group designator

Answer 18

Is a letter used to indicate the amount of residual nitrogen remaining in the divers body following a previous dive.

Question 19

Residual nitrogen time

Answer 19

Is the time that must be added to the bottom time of a repetitive dive to compensate for the nitrogen still in solution in a divers tissues from the previous dive. Residual nitrogen time is expressed in minutes.

Question 20

Equivalent single dive

Answer 20

A repetitive dive is converted to its single dive equivalent before entering the decompression tables to determine the decompression requirement.

Question 21

Equivalent single dive time

Answer 21

Is the sum of the residual nitrogen time and the bottom time of a repetitive dive.

Question 22

Surface decompression

Answer 22

Is the technique where some of the decompression stops in the water are skipped. These stopes are made up by compressing the diver back to depth in a recompression chamber on surface.

Question 23

Exceptional exposure dive

Answer 23

A dive in which the risk of decompression sickness, oxygen toxicity, and/or exposure to the elements is substantially greater than on a normal working dive.