AIR DECOMPRESSION Flashcards
stage depth is used to compute the _______ and ________ to the first stop or surface
- distance
- travel time
pneumofathometer correction factors:
0-100
101-200
201-300
301-400
- 0-100: +1
- 101-200: +2
- 201-300: +4
- 301-400: +7
before the diver leaves the bottom, you should have:
- table / schedule
- first stop depth
- time to first stop
- time to 50 fsw
the ascent rate for decompression tables is ____ fpm unless conducting what type of dive?
- 30 fpm
- surD dives
decompression stop time begins when:
the divers leave the previous stop
if there isn’t a repetitive group designator listed for the current table and schedule, the divers are not eligible for repetitive diving and must wait _________ from last dive before conducting another dive
18 hours
when does O2 time begin for air/O2 in water decompression?
when all divers are confirmed on O2
if more than :30 of O2 time is required by the selected table and schedule, a ____ air break is required every ____
- :05
- :30
do air breaks count toward O2 time?
no
for dives in which the first stop is at 40 fsw or deeper, the T/S/V time includes the ___ ascent time from 40 to 30 fsw as well as the time required to ____________, __________, and __________
- ::20
- shift console to oxygen, vent the divers, and confirm on O2
for dives in which the first stop is an oxygen stop at 30 or 20 fsw, the T/S/V time only includes:
the time required to shift the console, vent the divers, and confirm that they are on oxygen
(travel time to first stop is not included)
travel / shift / vent time should be under ___
:03
if the final or total oxygen stop time is ____ or less, an air break is not required at :30
:35
if the final or total oxygen stop time is :35 or less, an air break at :30 is not required and the divers will surface on _____ upon completion of ____________
- 100% O2
- the oxygen stop time
what factors dictate the use of SurD?
- cold water
- tired diver
- sea state
- ship slipping in moor
- combat situation
- training
what are the advantages of surface decompression?
- shorter exposure time in water
- maintenance of constant pressure (depth control)
- close observation
- diver safety
for SurD ascent rate is ____ up to 40 fsw
30 fpm
for SurD when decompression is completed at 40 fsw, the travel rate up to the surface is at ______
40 fpm
when does undress time begin for SurD? When does it end?
when divers REACH SURFACE from the water and ends when divers LEAVE SURFACE in the chamber
T/F: the undress time is considered “still under pressure”
true
descent in the chamber is ______ maximum
100 fpm
the total elapsed time from when the divers leave the 40 fsw stop (or when traveling past 40 fsw if no stops are required) to when they reach the 50 fsw stop in the recompression chamber shall not exceed ______ without incurring a penalty
:05 (surface interval = :05)
when does oxygen breathing begin for SurD?
upon arrival at 50 fsw in the chamber
the first oxygen period consists of ____ at ____, followed by ____ at ____
- :15 at 50 fsw
- :15 at 40 fsw
for SurD, ascent time from 50 to 40 fsw is included in the _________
first oxygen period
for SurD, oxygen periods 2-4 are spent at ____ fsw
40 fsw
for SurD, if more than 4 oxygen periods are requried, periods 5-8 are spent at ____ fsw
30 fsw
for SurD, ascent from 40 to 30 fsw, if required, should take place during:
an air break
are air breaks counted as “dead time” or “oxygen time”?
dead time
what is the protocol for when travel rate is exceeded?
- stop ascent
- allow watches to catch up
- continue ascent
what is the protocol for early arrival at the first decompression stop?
- begin stop time when required travel time has been completed
- if first stop is an O2 stop, shift divers to O2 upon arrival at stop. begin stop time when both divers are confirmed on O2 and required travel time is complete
what is the protocol for delay up to 1 minute arriving at the first stop?
disregard
what is the protocol for delay greater than 1 minute (deeper than 50 fsw) arriving at the first stop?
- round up to next whole minute and add to BT
- recompute table and schedule
- if new T/S calls for deeper deco stops than diver’s current depth, do not go deeper (perform any required deco time for deeper stops at the diver’s current depth)
what is the protocol for delay greater than 1 minute (shallower than 50 fsw) arriving at the first stop?
round delay up to next whole minute and add to diver’s FIRST DECOMPRESSION STOP time
what is the protocol for a delay between stops < 1 minute?
disregard
what is the protocol for a delay between AIR stops < 1 minute?
disregard
what is the protocol for delay > 1 minute leaving or between AIR stops deeper than 50 fsw?
round delay up to next whole minute, add to BT and recalculate required decompression
what is the protocol for delay > 1 minute leaving an AIR stop or between AIR stops shallower than 50 fsw?
- ignore delay
2. resume normal schedule after completion of the delay
what is the protocol for delay leaving an O2 stop at 30 fsw or between the 30 fsw and 20 fsw stops?
- subtract any delay in leaving the 30 fsw O2 stop or any delay during travel from 30 to 20 fsw on O2 from the subsequent 20 fsw stop time
- if the delay causes the total time on O2 deeper than 20 fsw to exceed :30, shift the divers to air at the :30 mark
- when the problem has been resolved, shift the divers back to O2
- ignore any time spent on air
what is the protocol for delay in leaving the 20 fsw stop?
delays leaving the 20 fsw stop may be ignored however do not leave the divers on O2 longer than 30 minutes
what is the protocol for delay in travel from 40 fsw to the surface during surface decompression?
disregard unless the 5 minute surface interval from 40 fsw in the water to 50 fsw in the chamber is exceeded
definition: repetitive dive
any dive conducted while nitrogen from a previous dive is still present
definition: surface interval
begins when diver RS and ends when diver LS
for repet diving, if the surface interval is < 10 minutes, add BT of previous dive to that of repet dive using schedule for deeper of the two dives and ___________
combine BTs
repet dives can be made following SurD dives as long as:
there is a repet group designator listed
because of the ___________ (reduced / increased) atmospheric pressure, dives conducted at altitude require _________ (less / more) decompression than identical dives conducted at sea level
- reduced
- more
altitude correction for:
0-300 ft
none
altitude correction for:
300-1000 ft
correct dives 145 fsw and deeper
altitude correction for:
1000-10,000 ft
correct all dives
altitude correction for:
above 10,000 ft
contact NAVSEA 00C for guidance
exceptional exposure dives are defined by:
the required decompression time for the decompression mode selected
what are the criteria for exceptional exposure dives?
- any dive deeper than 190 fsw
- any in-water decompression dive with a total decompression time on air or air/oxygen greater than 90 minutes
- any SurDO2 dive with a chamber oxygen time > 120 minutes (4 oxygen periods)
how do you convert ACF to SCF?
ACF x ATA = SCF
how do you convert SCF to ACF?
SCF / ATA = ACF
definition: minimum manifold pressure
supply pressure that will ensure that the gas supply will be delivered at a sufficient pressure to overcome the ambient seawater pressure and allow the equipment to supply the required amount of air to ventilate the rig being used
what is the MMP for a MK 20?
90 psig
how do you calculate MMP?
MMP = [depth x 0.445] + 90
round up to next whole number
how do you calculate the MMP for KM-37 at
- 60 fsw or less
- 61-130 fsw
- 131 fsw or more
- < 60 fsw @ 90 psig = [depth x 0.445] + 90
- 61-300 fsw @ 135 psig = [depth x 0.445] + 135
- > 131 fsw @ 165 psig = [depth x 0.445] + 165
calculate: SEV
SEV = ATA x %gas
