USN Diving Manual Rev 6 Chapter 9 MTT

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USN Diving Manual Rev 6Chapter 9 MTT
MDV REISS NDC SHAFER
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Schedule of Events

• Decompression Tables
• No Decompression Limits and RNT Group Designators
  for No D Dives
  
• Appendix 2A (30-50 fsw)
• Residual Nitrogen Time Table for Repetitive Dives
  (RNT)
  
• Air Decompression
• In Water Air, In Water Air and Oxygen, Sur D O2
• Surface Level Equivalent Depth Table (SLED)
• Repetitive Groups Associated with Initial Ascent
  to Altitude Table
  
• Required Surface Interval Before Ascent to
  Altitude after Diving
  
• General Rules for Decompression
• Selection of Decompression
• Repetitive Diving
• RNT Exception
• MK 16 Repetitive Diving
• Variations in Rates of Ascent
• Exceptional Exposure
• Charting

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Schedule of Events

• No Decompression Diving
• Chart
• Decompression Diving
• In Water Air
• Chart
• In Water Air and Oxygen
• ORCA
• Procedures for Shifting to 100 Oxygen at 30 and
  20 fsw
  
• Air Breaks at 30 and 20 fsw
• Chart
• Surface Decompression on Oxygen (Sur D O2)
• Sur D O2 Procedure
• Chart

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Schedule of Events

• Emergency Procedures
• Loss of Oxygen in the Water
• Contamination of Oxygen Supply with Air
• CNS O2 Toxicity (Non convulsive) at 30 and 20 fsw
  Stop
  
• CNS O2 Toxicity Convulsion at 30 and 20 fsw Stop
• Loss of O2 in the Chamber
• CNS O2 Toxicity in the Chamber
• Asymptomatic Omitted Decompression
• Decompression Sickness in the Water

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Appendix 2A

• The Optional Shallow Water Diving Tables
• Expansion of No D Tables 9-7 and 9-8
• Small Change in Depth Can Result in Significant
  Change in No D Limit
  
• Ship Husbandry Diving
• Shallow Air Diving Applications
• Depth is known
• Ballast tank
• Electronic monitoring

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Appendix 2A
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Appendix 2A
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Air Decompression Table
In H20 D 15
In H20 Air D 90
In H20 Air/O2 D 90
Chamber O2 Periods 4
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Air Decompression Table
100/40 In Water Air Decompression
100/90 In Water Air/O2 Decompression
100/110 Sur D O2 Decompression
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Surface Level Equivalent Depth Table (SLED)
Same Chart
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Repetitive Groups Associated with Initial Ascent
to Altitude Table
New Table Repet Group Designators Have Chang
ed
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Required Surface Interval Before Ascent to
Altitude after Diving
New Table with different times
The Note Addressing the lack of a Repet group
Designator on Sur D Dives was Deleted
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Selection of Decompression
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Selection of Decompression

• There are three modes of decompression
• In-water Decompression on Air
• In-water Decompression on Air/O2
• Surface Decompression on Oxygen
• (Sur D O2)

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Selection of Decompression

• Selecting the Decompression Schedule
• Schedule selection same (Bottom time and Depth)
• Pnuemo correction same
• Descent Rate
• Same, NTE 75 fpm
• Sur D O2, NTE 100 fpm
• Ascent Rate
• No Decompression, In Water Decompression
• 30 fpm (Bottom to 1st stop, Between Stops, Last
  Stop to Surface)
  
• Surface Decompression
• 40 fpm from the 40 foot water stop

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Selection of Decompression

• Decompression Stop Time
• 1st Stop time begins upon arrival and ends when
  diver leaves the stop
  
• Subsequent stops the stop time begins when the
  diver leaves the previous stop and ends when
  diver leaves the stop.
  
• In other words time between stops is included in
  the subsequent stop time
  
• Same rules apply to in-water decompression on
  air/oxygen with the exception of the first stop
  on oxygen. The time at the first oxygen stop
  begins when all divers are confirmed on oxygen
  and ends when the divers leave the stop.
• Last Water Stop
• 20 fsw for all In Water Decompression
• Eligibility for Surface Decompression
• Completion of the 40 foot stop
• If no stop, continue to surface

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Repetitive Diving
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Repetitive Diving

• At depths of 10, 15, and 20 FSW, some of the
  higher repet groups do not have a defined RNT
  time.
  
• These groups are marked w/ a double asterisk ()
  in the lower half of Table 9-8.
  
• The RNT is undefined because the tissue nitrogen
  loading associated with those repetitive groups
  is higher than the nitrogen loading that could be
  achieved even if the diver were to remain at
  those depths for an infinite period of time.

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Repetitive Diving

• A diver entering a dive at one of those higher
  groups marked by a can still perform a
  repetitive dive to 10, 15, or 20 FSW because the
  No-D times at those depths is unlimited.
• An RNT time is not required to make the dive.
• If a subsequent repetitive dive to a deeper depth
  is planned, however, the diver will need a repet
  group at the end of the shallow dive in order to
  continue using the RNT table.
• If a is encountered in Table 9-8, assume that
  the repet group remains unchanged during the
  course of the dive at 10,15, or 20 FSW.
  
• (Rev 6, pg 9-23, paragraph 9-9.1 step 8.)

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Repetitive Diving

• If a repetitive group is not shown in the
  decompression schedule, repetitive dives deeper
  than 20 fsw are not allowed following a dive on
  that schedule. The diver must remain on the
  surface for _at_ least 18hrs before making a dive
  deeper than 20 fsw.
• Do not perform repetitive dives that require the
  use of Exceptional Exposure decompression
  schedules.
  
• (Rev 6, pg 9-23, paragraph 9-9.1 step 9.)

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Repetitive Diving

• Order of Repetitive Dives.
• The most efficient way to perform repetitive
  dives is to perform the deepest dive first and
  the shallowest dive last.
  
• This pattern yields the most bottom time for the
  least decompression time. There is no prohibition
  on performing repetitive dives in the reverse
  order, i.e., shallowest dive first and deepest
  dive last, or in any random order if the
  operational situation requires it.
• Patterns other than deep to shallow are not the
  most efficient in terms of decompression.
  

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Repetitive Diving

• Computation of ESDT is the same
• RNT Exception Rule.
• In some cases, the residual nitrogen time given
  in Table 9-7 may be longer than needed to provide
  adequate decompression on the repetitive dive.
  This situation is most likely to occur when the
  surface interval between the dives is short.
• After determining the decompression requirement
  for the repetitive dive using the procedure in
  paragraph 9-9.1, the diver should recalculate the
  requirement by summing the bottom times of the
  two dives and taking the deepest depth.
• If the resultant table and schedule produces a
  longer no-decompression time or a shorter
  decompression time than the procedure in
  paragraph 9-9.1, the table and schedule with the
  lesser decompression obligation may be used. This
  alternative method of determining the table and
  schedule is referred to as the RNT Exception Rule.

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RNT Exception

• Repet Depth can be less than the initial dive,
  the same or deeper.
  
• If RNT is more than previous bottom time add the
  2 bottom times to get ESDT.
  

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MK 16 Repetitive Diving

• The repetitive group designators for air diving
  and MK 16 MOD 0 and MOD 1 diving are defined
  identically.
  
• It is possible to perform a repetitive dive on
  air following either a MK 16 MOD 0 or a MK 16 MOD
  1 nitrogen-oxygen dive using the existing tables.
  
• To perform a repetitive dive on air following a
  nitrogen-oxygen dive on either the MK 16 MOD 0 or
  MOD 1, take the following steps

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MK 16 Repetitive Diving

• Obtain the repetitive group designator after
  surfacing from the MK 16 dive from Table 17-6 or
  17-9 (MOD 0) or from Table 18-9 or 18-11 (MOD
  1).
• Using the MK 16 repetitive group designator,
  enter the top half of Table 9-8 on the diagonal.
  From this point the procedure is identical to
  making a repetitive dive on air following an air
  dive.

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MK 16 Repetitive Diving

• MK-16 N2 / 02 repet dives are integrated with air
  Surface Interval Credit Table
  
• Can be used both ways
• Not for use with MK-16 HE02 dives

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Variations in Rates of Ascent

• Travel Rate Exceeded
• Stop the ascent
• Allow the watches to catch up
• Continue ascent.

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Variations in Rates of Ascent

• Early Arrival at the First Decompression Stop
• Begin stop time when required travel time has
• been completed.
• If the 1st stop is an Oxygen stop, shift the
  divers to O2 upon arrival at the stop. Begin stop
  time when both divers are confirmed on O2 and
  required travel time is complete.

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Variations in Rates of Ascent

• Delay Arriving at 1st Decompression Stop
• Delay up to 1 minute Disregard
• Delay greater than 1 minute, deeper than 50FSW
• Round up to next whole minute add to the Bottom
  Time.
  

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Variations in Rates of Ascent

• Recompute the Decompression Schedule.
• If a change calls for deeper decompression stops
  than the divers current depth perform any
  missed stops at the divers current depth
  
• Do Not Go Deeper

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Variations in Rates of Ascent

• DELAYS BETWEEN STOPS
• Delay
• Delay 1 min between air stops Disregard
• Note
• The stop time starts when the divers leave the
  previous stop

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Variations in Rates of Ascent

• Delay greater than 1 minute, leaving or
  between air stops deeper than 50 FSW
  
• Add the delay to the bottom time and recalculate
  the required decompression.
  
• Note
• If new a schedule is required, pick up new
  schedule at the present stop or subsequent stop.
  Ignore any missed stops, or time deeper than the
  depth which the delay occurred

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Variations In Rate Of Ascent

• Delay greater than 1 minute leaving an air
  stop or between air stops shallower than 50 FSW
  
• Ignore delay. Resume normal schedule after
  completion of the delay.
  

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Variations in Rates of Ascent

• Delay leaving an Oxygen stop at 30 FSW or
  between the 30 FSW and 20 FSW stops
  
• Subtract any delay in leaving the 30 FSW oxygen
  stop or any delay during travel from 30 to 20
  on oxygen from the following 20 stop time.
  
• If the delay causes the total time on oxygen
  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
  oxygen. Ignore any time spent on air.

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Variations in Rates of Ascent

• Delay in leaving the 20 FSW Oxygen stop
• Delays leaving the 20 FSW stop may be ignored.
  However, do not leave the divers on oxygen longer
  than 30 minutes.

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Variations in Rates of Ascent

• 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. Follow guidance in paragraph 9-12.6
  (Emergency Procedures)

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Exceptional Exposure

• Exceptional exposure dives are defined by the
  required decompression time for the decompression
  mode selected.
  
• The following air dives are considered
  exceptional exposure
  
• 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
  greater than 120 minutes (4 oxygen periods).

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Exceptional Exposure

• NOTE
• The Commanding Officer must have CNO approval to
  conduct planned exceptional exposure dives.
  

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No Decompression Diving

• Use the No-Decompression Limits Repetitive
  Group Designation Table
  
• At stops less than 20 no limit on time spent at
  depth.
  
• A repetitive group designator must be assigned to
  a divers subsequent dive, even no-d.

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No-Decompression Dive
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Decompression Diving

• -In Water Decompression on Air.
• Use this mode when entire decompression will be
  on Air.
  
• Use the entire top row on the Table marked Air.
• Last decompression stop is 20fsw, there are no
  10 stops

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Decompression Diving
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In-Water Air Decompression
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Oxygen Regulator Console Assembly (ORCA II)
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ORCA II

• Provides 100 O2 for Air O2 In-Water
  Decompression
  
• Connects to any certified DLSS
• Minimum O2, (3) K-bottles 517 scf
• (1) CAOS rack 522 scf

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ORCA II Configuration

• OPTIONS
• HP O2 only, ORCA will accept (2) HP sources
• ORCA HP (1) reducer
• HP primary and LP O2 as secondary
• CAOS rack is ideal. Provides HP and LP source
• K-bottles with adequate reducer. Provides HP and
  LP
  

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In Water Air/Oxygen

• Decompression conducted partly on air and partly
  on 100 Oxygen.
  
• Use the Air/O2 row to get stop times
• (O2 times are printed in BOLD numbers)
• Follow the air schedule to 30 FSW and shift
  divers to 100 oxygen at 30 FSW (or 20 FSW if not
  a 30 FSW stop)
  

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In Water Air/Oxygen

• Oxygen stop time starts when all divers are
• confirmed on Oxygen. (Vent each diver 20)
• 5 minute air breaks must be taken for every 30
  spent on oxygen. If the final O2 period is 35 or
  less, disregard the last 05 air break.
  
• Upon completion of the 20 FSW O2 stop, the
  divers surface at 30 FSW/MIN breathing oxygen.

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In Water Air/Oxygen

• Procedures for shifting to 100 oxygen _at_ 30
  20 fsw.
  
• Align ORCA or FMGS to supply 100 oxygen to the
  diver.
  
• Ventilate each diver 20 seconds. Divers may be
  ventilated simultaneously
  
• Verify 100 O2 to divers on O2 monitoring device
  if present.

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In Water Air/Oxygen

• Travel, Shift, Vent
• The Air Diving Chart has a place to enter the
  Travel/Shift/Vent time.
  
• If the first stop is 40 FSW or deeper the
  travel/shift/vent time includes the 20 ascent
  from 40 FSW to 30 FSW as well as the time it
  takes to shift to O2, vent the divers, and
  confirm the divers are on Oxygen.
• If the first stop is an oxygen stop at 30 FSW or
  20 FSW the travel/shift/vent time only includes
  the time required shift to O2, vent the divers,
  and confirm the divers are on Oxygen.

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In Water Air/Oxygen

• Air breaks _at_ 30 and 20 fsw.
• Oxygen stop time starts when all divers are
• confirmed on Oxygen. (Vent each diver 20)
• 5 minute air breaks must be taken for every 30
  spent on oxygen. If the final O2 period is 35 or
  less, disregard the last 05 air break.
  
• Upon completion of the 20 FSW O2 stop, the
  divers surface at 30 FSW/MIN breathing oxygen.

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In-Water Air/O2 Decompression
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Surface Decompression on Oxygen (SurD02)

• Complete any stops on air deeper than 40 FSW.
• Upon completion of the 40 FSW stop surface the
  divers at 40 FSW/MIN.
  

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Surface Decompression on Oxygen (SurD02)

• If a 40 FSW stop is not required, bring the
  divers from the bottom to 40 FSW at 30 FSW/MIN
  surface the divers from 40 FSW _at_ 40 FSW/MIN.
  
• (Travel from 40 FSW to Surface 01)
• Once the divers are on the surface the tenders
  have 330 to undress the divers and assist them
  to the recompression chamber.
  

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Surface Decompression on Oxygen (SurD02)

• Place the divers in the recompression chamber.
  Divers will monitor each other for signs of
  Oxygen Toxicity.
  
• (If only one diver, use a tender in the chamber
  to monitor the diver on oxygen)
  

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Surface Decompression on Oxygen (SurD02)

• Upon arrival at 50 FSW in the chamber place the
  divers on 100 Oxygen by BIBS mask.
  
• Divers will breathe oxygen for the required
  number of oxygen periods is specified in the Air
  Decompression Table.
  

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Surface Decompression on Oxygen (SurD02)

• The 1st Oxygen period consists of 15 _at_ 50 FSW
  and 15 _at_ 40 FSW.
  
• Periods 2-4 are spent at 40 FSW.
• If more than 4 periods are needed, complete them
  at 30 FSW.
  
• Ascent rate in the chamber is 30 FSW/MIN.
• Ascent time from 50 FSW to 40 FSW is included in
  the first Oxygen period.

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Surface Decompression on Oxygen (SurD02)

• Interrupt oxygen breathing every 30 with a 05
  air break. Air time is dead time. Oxygen time
  begins when divers are confirmed on O2 _at_ 50 FSW.
  
• When the last oxygen period has been completed
  return the divers to chamber air and surface the
  chamber at 30 FSW/MIN.

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Surface Decompression on Oxygen (SurD02)

• Surface Decompression from 30 and 20 FSW
• The Diving Supervisor can initiate Surface
• Decompression (Sur-D) at any point during
  in-water decompression at 30 FSW or 20 FSW
  regardless of breathing media (Air or Oxygen).
  
• The diving supervisor may elect to do the full
  number of oxygen breathing periods called for in
  the Air Decompression Table. -OR-

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Surface Decompression on Oxygen (SurD02)

• The diving supervisor may elect to take credit
  for the time already spent on air or oxygen in
  the water.
  
• If Sur-D is elected before the divers are shifted
  to oxygen, take the full number of chamber stops
  required by the Air Decompression Table.

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Surface Decompression on Oxygen (SurD02)

• If Sur-D is elected after the divers are on
  oxygen compute the number of chamber stops
  required by multiplying the remaining in-water
  oxygen time by 1.1 and divide by 30, then round
  up to the next higher half period.
• Note
• ½ period(15) _at_ 50 FSW is the minimum requirement.

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• To Sur D after 4 min at 20 fsw due to rough seas
• 02 time remaining 44 - 04 40 min
• 40 min 02 remaining
• 40 X 1.1 44 min
• 44 1.46 Round up 1.46 to 1.5 chamber
  period
  
• 30
• Diver must spend 15 min at 50 ft and 30 min at 40
  ft on 02 in chamber
  
• 15 min at 50 ft minimum

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Surface Decompression on Oxygen (SurD02)

• Surface decompression from 30 FSW or 20FSW
  while divers are decompressing on AIR
  
• First, convert the remaining air time at the
  stops to an equivalent oxygen time at those
  stops then convert this remaining oxygen time to
  the number of chamber oxygen periods required by
  multiplying by 1.1 and then divide by 30 (min),
  round up to the next whole period.

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Surface Decompression on Oxygen (SurD02)

• For divers at 30 FSW
• Compute the Air/Oxygen Trading Ratio at 30 FSW by
  dividing the 30 FSW Air stop time by the 30 FSW
  Oxygen stop time.
  
• Next, divide the remaining air time at 30 FSW by
  the air/oxygen trading ratio to determine the
  equivalent remaining oxygen time at 30 FSW.
  
• Add the oxygen time for the 20 FSW stop to the
  equivalent remaining oxygen time at 30 FSW to
  obtain the total remaining oxygen time.

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Surface Decompression on Oxygen (SurD02)

• For divers at 20 FSW
• Compute the air/oxygen trading ratio at 20 FSW by
  dividing the 20 FSW air stop time listed in the
  table by the 20 FSW oxygen time.
  
• Divide the remaining 20 FSW air stop time by the
  trading ratio to obtain the equivalent remaining
  oxygen time.
  
• Then (1.1 x Remaining Time) / 30 O2 Periods

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Air / Oxygen Trading Ratio

• Ratio is calculated by dividing the air time by
  the oxygen time
  
• 30 fsw 02 stop
• 14 1.75 or 28 2
• 8 14
• 20 fsw 02 stop
• 84 2.62 or 164 3.72
• 32 44

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Surface Decompression on Oxygen (SurD02)

• Example A diver is decompressing on a schedule
  that calls for a single 50 min stop on air at 20
  fsw. The corresponding 20-fsw oxygen stop time is
  27 min. After 20 minutes on air at 20 fsw, the
  diving supervisor elects to surface decompress
  the diver. The air/oxygen trading ratio at 20 fsw
  is 50/27 1.85, i.e., every 1.85 minutes spent
  air at 20 fsw is the equivalent of 1 minute spent
  on oxygen at 20 fsw. The remaining time on air at
  20 fsw is 50 20 30 minutes. The equivalent
  remaining oxygen time at 20 fsw is 30/1.85 16.2
  minutes. This remaining oxygen time is rounded up
  to the next whole minute, 17 min. The number of
  30-min SurDO2 periods required is (1.1 17) / 30
  0.62. This number is rounded up to 1.0.

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Emergency Procedures

• Factors to consider
• If EP takes you to chamber 15 min at 50 ft
• If EP directs a shift from In-Water O2 to
  chamber multiply remaining O2 time by 1.1
  
• If EP directs a shift from O2 to air, multiply
  remaining O2 time by Air /O2 ratio

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Emergency Procedures

• Bottom Time in Excess of the Table
• In the rare instance of diver entrapment or
  umbilical fouling, bottom time may exceed the
  longest bottom time listed in the table for the
  divers depth.
• When it is foreseen the bottom time will exceed
  the longest listed value, immediately contact the
  Navy Experimental Diving Unit for advice on how
  to decompress. If the Navy Experimental Diving
  Unit cannot be contacted in time, take the
  following action

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Emergency Procedures

• Bottom Time in Excess of the Table
• 1. If available, use the U.S. Navy Thalmann
  Algorithm Dive Planner to compute the
  decompression requirement.
  
• 2. Read down to deeper depths in the Air
  Decompression Table until a depth is found that
  has a schedule that is equal to or longer than
  the bottom time. The Air Decompression Table
  contains longer schedules at various depths
  especially for this purpose.

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Emergency Procedures

• Bottom Time in Excess of the Table
• Example A diver is trapped on the bottom at
  a depth of 155 FSW. By the time he is freed, the
  bottom time is 100 min. The longest schedule in
  the 160 FSW table is 80 min. Read down to the 170
  FSW table. The 120 min schedule is longer than
  the divers bottom time. Decompress the diver on
  the 170 FSW / 120 minute schedule.

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Emergency Procedures

• Loss of Oxygen supply in the water
• 1. Have the diver continue to breathe air while
  the problem is investigated.
  
• 2. If the problem can be corrected quickly,
  ventilate the diver with oxygen as soon as the
  gas supply is restored. Consider any time spent
  on air as dead time. Remain on oxygen at the stop
  for the full stop time listed in the table.

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Emergency Procedures

• Loss of Oxygen supply in the water
• 3. If the problem cannot be corrected, initiate
  surface decompression or continue decompression
  in the water on air. In this situation, the
  surface interval for surface decompression is the
  time from leaving the in-water stop to reaching
  the 50 FSW stop in the recompression chamber.

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Emergency Procedures

• Loss of Oxygen supply in the water
• If the oxygen supply is lost during the 30
  or 20 FSW water stops after the diver has shifted
  to oxygen
  
• 1. Shift the diver back to air.
• 2. If the problem can be corrected quickly,
  re-ventilate the diver with oxygen and resume the
  schedule at the point of interruption. Consider
  any time spent on air as dead time.

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Emergency Procedures

• Loss of Oxygen supply in the water
• 3. If the problem cannot be corrected and a
  recompression chamber is available on the dive
  station, initiate surface decompression. Compute
  the number of chamber oxygen periods required by
  multiplying the remaining oxygen time at the
  stops by 1.1, dividing the total by 30 minutes,
  then rounding the result up to the next highest
  half period. One half period (15 minutes at 50
  FSW) is the minimum requirement.

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Emergency Procedures

• Loss of Oxygen supply in the water
• Example The oxygen supply is lost
  permanently when the diver has a remaining oxygen
  time of 5 minutes at 30 FSW and 33 minutes at 20
  FSW. The total remaining oxygen time is 38
  minutes. The number of 30-min SurDO2 periods
  required is
• (1.1 38) / 30 1.39. This number is
  rounded up to 1.5.

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Emergency Procedures

• Loss of Oxygen supply in the water
• 4. If the problem cannot be corrected and a
  recompression chamber is not available on the
  dive station, continue decompression on air in
  the water. Compute the remaining stop time on
  air at the depth of the loss by multiplying the
  remaining stop time on oxygen at that depth by
  the ratio of the air stop time to the oxygen time
  at that depth.

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Air / Oxygen Trading Ratio

• Ratio is used to determine decompression
  obligation for dives were 02 breathing is
  discontinued.
  
• Examples
• Loss of In-Water 02 or chamber
• 02 toxicity In-Water or chamber

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Emergency Procedures

• Loss of Oxygen supply in the water
• Example The oxygen supply is lost
  permanently when the diver has a remaining oxygen
  time of 10 minutes at 20 FSW. His decompression
  schedule calls for either 140 minutes on air at
  20 FSW or 34 minutes on oxygen at 20 FSW. The
  ratio of air stop time to oxygen time at the
  20-fsw stop is 140/34 4.12. His remaining time
  on air at 20 fsw is 10 4.12 41.2 minutes.
  Round this time up to 42 minutes.

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Emergency Procedures

• Loss of Oxygen supply in the water
• 4. (cont) If the shift to air occurs at 30 FSW,
  compute the remaining stop time on air at 30 FSW
  as shown above, then take the full 20-fsw air
  stop as prescribed in the Air Decompression Table.

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Emergency Procedures

• Contamination of Oxygen Supply with Air
• It will be difficult to detect mixing of air with
  the oxygen supply during oxygen decompression in
  the water as no voice change will occur as it
  does in helium-oxygen diving.

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Emergency Procedures

• Contamination of Oxygen Supply with Air
• On shifting to oxygen, the ORCA/Console operator
  should verify that the ORCA is properly lined up
  and that the oxygen monitor, if one is present,
  indicates 100 oxygen going to the divers
  umbilical.
• The diver should monitor his EGS pressure gauge
  periodically to ensure that there is no drop in
  pressure.
  

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Emergency Procedures

• Contamination of Oxygen Supply with Air
• If the operator discovers that the ORCA/Console
  is
  
• improperly lined up, take the following action
• 1. Align the ORCA properly.
• 2. Re-ventilate each diver with oxygen for 20
  seconds.
  
• 3. Restart oxygen time. Consider any time spent
  on contaminated oxygen as dead time.
  

87
Emergency Procedures

• CNS Oxygen Toxicity Symptoms
• (Non-convulsive) at 30 or 20 FSW Water Stop
• 1. Chamber available, Sur-D , Shift the console
  to air during travel to the surface.
  
• -Compute the chamber oxygen periods required
  by multiplying the remaining oxygen time at the
  stops by 1.1, dividing the total by 30 minutes,
  then rounding the result up to the next highest
  half period.
• -One half period (15 minutes at 50 FSW) is
  the minimum requirement.

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Emergency Procedures

• CNS Oxygen Toxicity Symptoms
• (Non-convulsive) at 30 or 20 FSW Water Stop
• Chamber not available at 30 FSW
• 2. Bring divers up 10 FSW shift to air to
  reduce the partial pressure of oxygen (shift
  during travel).
  
• -Vent both divers upon arrival at 20 FSW, vent
  affected diver first.
  
• -Complete the decompression on air at 20 FSW.

89
Emergency Procedures

• CNS Oxygen Toxicity Symptoms
• (Non-convulsive) at 30 or 20 FSW Water Stop
• Chamber not available at 30 FSW
• 2. (cont) Compute the 20 FSW stop time as
  follows
  
• -Multiply the missed stop time on oxygen at 30
  FSW by the air/oxygen ratio for the 30 FSW stop
  time to obtain the equivalent air stop time.
  
• -Add this time to the time shown for the 20
  FSW stop time in the Air Decompression Table.

90
Emergency Procedures

• CNS Oxygen Toxicity Symptoms
• (Non-convulsive) at 30 or 20 FSW Water Stop
• Chamber not available at 20 FSW
• 3. Shift the console to air, vent both divers
  (affected diver first), complete the
  decompression in the water on air.
  
• - Compute the remaining stop time on air at 20
  FSW by multiplying the remaining stop time on
  oxygen at 20 FSW by the ratio of the air stop
  time to the oxygen time at 20 FSW.

91
Emergency Procedures

• CNS Oxygen Toxicity Symptoms
• (Non-convulsive) at 30 or 20 FSW Water Stop
• Example After 10 minutes on oxygen at 30
  fsw, a diver has a non-convulsive CNS oxygen
  toxicity symptom.
  
• A recompression chamber is not available on
  the dive station.
  
• The diver is immediately brought up to 20
  FSW and ventilated with air. His decompression
  schedule calls for 28 minutes on air at 30 FSW
  and 175 minutes on air at 20 FSW. The oxygen stop
  time at 30 FSW is 14 minutes.

92
Emergency Procedures

• CNS Oxygen Toxicity Symptoms
• (Non-convulsive) at 30 or 20 FSW Water Stop
• Example (Cont)
• The missed oxygen time at 30 FSW is 4
  minutes (14 4).
  
• The ratio of air to oxygen time at 30 FSW is
  
  
• 28/14 2.0.
• The missed air time at 30 FSW therefore is 4
  2.0 8 minutes. The required air decompression
  time at 20 FSW is 183 minutes (8 175).

93
Emergency Procedures

• CNS Oxygen Toxicity Symptoms
• (Non-convulsive) at 30 or 20 FSW Water Stop
• Example After 24 minutes on oxygen at 20
  FSW, a diver has a non-convulsive CNS oxygen
  toxicity symptom. The diver is shifted to air
  with 10 min of oxygen time remaining at 20 FSW.
  His decompression schedule calls for either 140
  minutes on air at 20 FSW or 34 minutes on oxygen
  at 20 FSW.

94
Emergency Procedures

• CNS Oxygen Toxicity Symptoms
• (Non-convulsive) at 30 or 20 FSW Water Stop
• Example (Cont) The ratio of air stop time to
  oxygen time at the 20-fsw stop is 140/34 4.52.
  His remaining time on air at 20 FSW is 10 4.52
  45.2 minutes. Round this time up to 46 minutes.

95
Emergency Procedures

• Oxygen Convulsion at the 30- or 20-fsw
• Water Stop
• 1. Shift divers to air.
• 2. Vent the unaffected diver, have him vent the
  affected diver.
  
• 3. Hold the divers at depth until the
  tonic-clonic phase of the convulsion has subsided
  (1-2 minutes).

96
Emergency Procedures

• Oxygen Convulsion at the 30- or 20-fsw Water
  Stop
  
• 4. At the end of the tonic-clonic phase, have
  the dive partner or standby ascertain if the
  affected diver is breathing.
  
• 5. If the diver appears NOT to be breathing, try
  to re-position the divers head to open the
  airway.
  
• Note
• Airway obstruction is the most common reason an
  unconscious diver fails to breath.

97
Emergency Procedures

• Oxygen Convulsion at the 30- or 20-fsw Water
  Stop
  
• 7. If the diver IS breathing, hold him at depth
  until he is stable, then surface decompress.
  Compute the number of chamber oxygen periods
  required by multiplying the remaining oxygen time
  at the stops by 1.1, dividing the total by 30
  min, then rounding the result up to the next
  highest half period.
• One half period (15 minutes at 50 FSW) is
  the minimum requirement.

98
Emergency Procedures

• Oxygen Convulsion at the 30- or 20-fsw Water
  Stop
  
• 8. If surface decompression is not feasible,
  continue decompression on air in the water.
  
• Compute the remaining stop time on air at
  the depth of the incident by multiplying the
  remaining stop time on oxygen at that depth by
  the ratio of the air stop time to the oxygen time
  at that depth.
• If the shift to air occurs at 30 FSW,
  compute the remaining stop time on air at 30 FSW,
  then take the full 20 FSW air stop as prescribed
  in the Air Decompression Table.

99
Emergency Procedures

• Oxygen Convulsion at the 30- or 20-fsw
  Water Stop
  
• 9. If it is not possible to verify that the
  affected diver is breathing, leave the unaffected
  diver at the stop to complete decompression, and
  surface the affected diver and the standby diver
  at 30 fsw/min.
• Treat for arterial gas embolism in
  accordance with Figure 20-1.

100
Emergency Procedures

• Surface Interval Greater than 5 Minutes
• 1. If the surface interval is less than or
  equal to 7 minutes, increase the time on oxygen
  at 50 FSW from 15 to 30 minutes, i.e., add
  one-half oxygen period to the 50 FSW stop.
• Ascend to 40 FSW during the subsequent air
  break. The 15-min penalty is considered a part of
  the normal surface decompression procedure, not
  an emergency procedure.

101
Emergency Procedures

• Surface Interval Greater than 5 Minutes
• Example Divers are decompressing on a
  SurDO2 schedule that requires 1.5 oxygen
  breathing periods.
  
• It took 6 minutes and 20 seconds to travel from
  40 fsw to the surface, undress the diver, and
  recompress to 50 fsw in the chamber.
  
• The divers are placed on oxygen at 50 fsw in the
  chamber. They will breathe oxygen at 50 fsw for
  the 15 minutes (one-half period) required by the
  original schedule plus an additional 15 minutes
  to compensate for exceeding the normal 5-min
  surface interval.

102
Emergency Procedures

• Surface Interval Greater than 5 Minutes
• Example Cont
• Upon completion of 30 minutes on oxygen at 50
  fsw, they will remove the BIBS to initiate a
  5-minute air break and ascend from 50 fsw to 40
  fsw at 30 fsw/min while breathing air.
• After 5 minutes on air, the divers will breathe
  oxygen for 30 minutes to complete the oxygen time
  required at 40 fsw on the original schedule.
  
• After 30 minutes on oxygen at 40 fsw, the divers
  will remove the BIBS and ascend to the surface at
  30 fsw/min breathing air.
  
• Because the divers exceeded the normal 5-minute
  surface interval, the total number of oxygen
  periods is increased from 1.5 to 2.0.

103
Emergency Procedures

• Surface Interval Greater than 5 Minutes
• 2. If the surface interval is greater than 7
  minutes, continue compression to a depth of 60
  FSW.
  
• Treat the divers on Treatment Table 5 if the
  original schedule required 2 or fewer oxygen
  periods in the chamber.
  
• Treat the divers on Treatment Table 6 if the
  original schedule required 2.5 or more oxygen
  periods in the chamber.

104
Emergency Procedures

• 3. Safe Way Out
• Used if the diver (s) cannot reach 50 FSW in the
  chamber due to ear problems.
  
• Compress the divers to the deepest depth they
  attain.
  
• Begin oxygen breathing at that depth.
• Continue to attempt to press divers deeper.
• Oxygen time starts when diver initially starts
  breathing oxygen.

105
Emergency Procedures

• 3. Safe Way Out
• If the Air/Oxygen schedule called for a 20 FSW
  stop, attempt to get the divers to 20 FSW in the
  chamber.
  
• If the Air/Oxygen schedule called for a 30 FSW
  stop, attempt to get the divers to 30 FSW in the
  chamber.
  
• Double the number of chamber oxygen periods
  indicated in the table and have the diver take
  these periods at whatever depth he is able to
  attain.

106
Emergency Procedures

• 3. Safe Way Out (cont)
• Interrupt oxygen breathing every 60 minutes with
  a 15-min air break. The air break does not count
  toward the total oxygen time.
  
• Upon completion of the oxygen breathing periods,
  surface the diver at 30 fsw/min.
  
• Carefully observe the diver post-dive for the
  onset of decompression sickness.
  
• Repetitive diving is not allowed following a dive
  in which the safe way out procedure is used.
  

107
Emergency Procedures

• Decompression Sickness During the Surface
  Interval
  
• If Type I Decompression sickness occurs during
  travel from 40 FSW in the water or during the
  undress phase.
  
• Compress diver in chamber to 50 FSW following
  normal Sur-D procedures.
  

108
Emergency Procedures

• Decompression Sickness During the Surface
• Interval
• If the SX resolve in the first 15 at 50 FSW, the
  SI was 05 or less, and no neurological SX are
  present increase the 50 FSW oxygen time from 15
  to 30 (.5 periods). Continue normal
  Decompression.
• Ascend from 50 FSW to 40 FSW during the
  subsequent air break.

109
Emergency Procedures

• If Type I symptoms do not resolve during the 15
  minute 50 FSW stop or symptoms resolve but the
  surface interval was greater than 5 minutes,
  compress the diver to 60 FSW on oxygen.
• Use TT-5 if schedule called for 2 or less oxygen
  periods.
  
• Use TT-6 if schedule called for 2.5 or more
  oxygen periods.
  
• Tx time begins upon arrival at 60 FSW.

110
Emergency Procedures

• If symptoms of Type II decompression sickness
  occur during travel from 40 FSW to the surface,
  during the surface undress phase, or the
  neurological examination at 50 FSW is abnormal,
  compress the diver to 60 FSW on oxygen.
• Treat diver on TT-6.
• Treatment time begins upon arrival at 60 FSW.
• Note
• In all cases follow guidelines for recompression
  treatments in Chapter 20.

111
(No Transcript)
112
Emergency Procedures

• Loss of Oxygen Supply in the Chamber
• Have the divers breathe chamber air. If the loss
  is temporary, return the diver to oxygen
  breathing. Consider any time spent on air as dead
  time.
• If the loss of the oxygen supply is permanent,
  complete decompression in the chamber on 50
  nitrogen/helium 50 oxygen (preferred) or on
  air.
• 50/50 available Multiply the remaining oxygen
  time by 2. Air breaks are not required when
  breathing 50/50 gas.

113
Loss of O2 in chamber 50/50 available

• Permanent loss of O2 10 into 40 ft chamber
  stop
  
• 02 time remaining 2 periods 60 - (1510)
  35
  
• 35 X 2 70
• Diver breathes 50/50 for 70 min at
  40 ft
  
• (no air break required/time off 50/50 is dead
  time)
  

114
Loss of O2 in chamber no 50/50 available

• Permanent loss of O2 10 into 40 ft chamber
  stop
  
• 02 time remaining 2 periods 60 - (1510)
  35
  
• Air / 02 Ratio is (20 130) 150 (air)
  150 3.12
  
• (11 37) 48 (02) 48
• 3.12 X 35 109.2 (round up) 110 min
• Diver breathes air for (110 X .1 10.5) 11 min
  at 40 ft
  
• Diver breathes air for (110 X .2 21.6) 22 min
  at 30 ft
  
• Diver breathes air for (110 X .7 75.6) 77 min
  at 20 ft
  

115
Emergency Procedures

• Loss of Oxygen Supply in the Chamber
• 50/50 NOT available Multiply the remaining
  chamber time on oxygen by Air/O2 trading ratio
  from the 30 20 FSW (water) stop times to obtain
  the equivalent chamber decompression time on
  air.
• Allocate the air or 50/50 breathing as follows
• 10 _at_ 40 FSW
• 20 _at_ 30 FSW
• 70 _at_ 20 FSW

116
Emergency Procedures

• Loss of Oxygen Supply in the Chamber
• If divers are at 50 FSW, ascend to 40 FSW and
  begin stop time.
  
• If loss occurs at 30 FSW allocate the air or
  50/50 breathing as follows
  
• 30 _at_ 30 FSW
• 70 _at_ 20 FSW
• Round up times to next whole minute.
• Surface divers upon completion of the 20 FSW stop.

117
Emergency Procedures

• Example A SurDO2 schedule calls for 2, 30-min
  oxygen periods in the chamber. The chamber oxygen
  supply is lost permanently after 28 minutes on
  oxygen at 50 and 40 FSW. Chamber air is the only
  gas available.
• O2 time (2 x 30) 28 32 remaining
• Original (water) air stops 52 140 192
  (30/20 fsw)
  
• Original O2 (water) stops 13 34 47
  (30/20 fsw)
  
• Air/O2 ratio 192/47 4.08
• 32 x 4.08 131 equivalent chamber air stop
  time

118
Emergency Procedures

• Loss of Oxygen Supply in the Chamber
• Example Cont
• Allocate the 131 chamber air time as follows
• 13 _at_ 40 FSW (131 x 0.1)
• 26 _at_ 30 FSW (131 x 0.2)
• 92 _at_ 20 FSW (131 x 0.7)

119
Emergency Procedures

• CNS Oxygen Toxicity in the Chamber
• At the first sign of CNS oxygen toxicity, the
  diver should be removed from oxygen and allowed
  to breathe chamber air.
  
• Fifteen minutes after all symptoms have
  completely subsided, resume oxygen breathing at
  the point of interruption.
  
• If symptoms develop again, or if the first
  symptom is a convulsion, take the following
  action

120
Emergency Procedures

• CNS Oxygen Toxicity in the Chamber
• 1. Remove the mask.
• 2. After all symptoms have completely subsided,
  decompress 10 feet at a rate of 1 fsw/min. For a
  convulsion, begin travel when the patient is
  fully relaxed and breathing normally.
• 3. Resume oxygen breathing at the shallower depth
  at the point of schedule interruption.

121
Emergency Procedures

• CNS Oxygen Toxicity in the Chamber
• 4. If another oxygen symptom occurs after
  ascending 10 FSW, complete decompression on
  chamber air. Compute the remaining chamber time
  on air the same as loss of chamber oxygen.
• Allocation of time is the same as Loss of O2.
• 10_at_ 40 FSW
• 20_at_ 30 FSW 30_at_ 30 FSW
• 70_at_ 20 FSW 70_at_ 20 FSW

122
Emergency Procedures

• Asymptomatic Omitted Decompression
• Missed decompression due to
• Uncontrolled ascent
• Exhausted air supply
• Bodily injury
• Note
• If the diver shows symptoms of decompression
  sickness or A.G.E. immediate treatment with the
  appropriate recompression table is essential,
  treat IAW Chapter 20 of the US Navy Diving Manual.

123
Emergency Procedures

• Asymptomatic Omitted Decompression
• Omitted decompression may be
• Planned There is time to consider options and
  ready the chamber and alert personnel.
  
• Unplanned The diver suddenly appears on the
  surface for some unforeseen reason.

124
Emergency Procedures
125
Emergency Procedures

• No-Decompression Stops Required
• Diver makes an ascent greater than 30 FSW/MIN but
  the dive itself is a No-Decompression dive.
  
• Observe on the surface for one hour. Watch for
  signs or symptoms of Decompression Sickness (DCS)
  or Arterial Gas Embolism (AGE).

126
Emergency Procedures

• Omitted Decompression Stops at 30 and 20 FSW
• 1. If on surface for and add 01 to stop time. Resume original
  schedule.
  
• 2. If the diver is on the surface for 1 to 5
  minutes and a recompression chamber is available
  on dive station, place the diver in the
  recompression chamber and complete the
  decompression using surface decompression.

127
Emergency Procedures

• Omitted Decompression Stops at 30 and 20FSW
• 2. (cont)
• If the diver was on oxygen at the time of the
  omission,
  
• Multiply the remaining oxygen time at the stops
  by 1.1
  
• Divide the total by 30 min, then round
• the result up to the next highest half
  period.
  
• (T x 1.1) / 30 O2 periods

128
Emergency Procedures

• Omitted Decompression Stops at 30 and 20FSW
• 2. (cont)
• If the diver was on air at the time of the
  omission,
  
• Compute the Air/Oxygen Trading Ratio.
• Divide the remaining air stop time by the Ratio.
• Multiply the equivalent O2 stop time by 1.1
• Divide the required chamber time by 30 to compute
  the number of oxygen periods (round up to the
  next ½ period).

129
Emergency Procedures

• Omitted Decompression Stops at 30 and 20FSW
• 2. (cont)
• If the diver is on the surface for 1 to 5 minutes
  and a recompression chamber is not available
  
• Return the diver to the depth of the omitted
  stop.
  
• Multiply the 30- and/or 20-fsw air or oxygen
  stops by 1.5.

130
Emergency Procedures

• Omitted Decompression Stops at 30 and 20FSW
• 3. If the diver is on the surface for more than 5
  minutes but less than or equal to 7 minutes and
  a recompression chamber is available on the dive
  station
• Use Surface Decompression.
• Increase the oxygen time at 50 FSW from 15 to
  30.

131
Emergency Procedures

• Omitted Decompression Stops at 30 and 20FSW
• 4.If the diver is on the surface for more than 7
  minutes and a recompression chamber is available
  on site
  
• Use TT-5 if original schedule called for 2 or
  less oxygen periods.
  
• Use TT-6 if original schedule called for 2.5 or
  more oxygen periods.

132
Emergency Procedures

• Omitted Decompression Stops at 30 and 20FSW
• 5.If the diver is on the surface for more than 1
  minute and no chamber available.
  
• Return diver to depth omitted.
• Complete decompression in the water my
  multiplying the 30 and /or 20 air or 02 stop by
  1.5.

133
Emergency Procedures

• Note
• Chamber On Station means the chamber is
  available for use on the dive station.
  
• Chamber On Site means that the chamber is
  within 30 by available transportation.
  

134
Emergency Procedures

• Omitted Decompression Stops Deeper than
  30fsw
  
• If the diver omits part or all of a decompression
  stop at 40 FSW or deeper and a recompression
  chamber is available on site, treat the diver
  with Treatment Table 6.
• If a recompression chamber is not available on
  site, return the diver to the depth of the first
  decompression stop.

135
Emergency Procedures

• Omitted Decompression Stops Deeper than 30
  fsw
  
• Follow the original decompression schedule to 30
  FSW . At 30 FSW, shift the diver to oxygen if it
  is available.
  
• Complete decompression from 30 FSW by multiplying
  the 30- and 20-fsw air or oxygen stops by 1.5.

136
Emergency Procedures

• Omitted Decompression Stops Deeper
• than 30 fsw
• Follow the original decompression schedule to 30
  FSW . At 30 FSW, shift the diver to oxygen if it
  is available.
  
• Complete decompression from 30 FSW by multiplying
  the 30- and 20-fsw air or oxygen stops by 1.5.

137
Emergency Procedures

• Decompression Sickness in the Water
• Launch standby and decompress other divers IAW
  original schedule.
  
• If on air, shift to Oxygen if available.
• Have diver descend 10 FSW, if significant relief
  not achieved, descend another 10 FSW. No deeper
  than 40 FSW if diver is breathing oxygen.
  
• Remain at treatment depth for at least 30.

138
Emergency Procedures

• Diver Remaining in the Water
• 1. Dispatch STBY to assist. Continue to
  decompress according to the original schedule.
  
• 2. If diver is on Air _at_ 30 or 20 switch to 100
  O2.
  
• 3. Have diver descend 10 fsw. If significant
  relief not obtained press an additional 10, but
  no deeper than 40 fsw if on 100 02.
  
• 4. Remain _at_ treatment depth for 30 min.

139
Emergency Procedures

• 5. If diver is on air
• Multiply all air/oxygen stops by 1.5.
• If the treatment goes deeper than the original
  first stop, do stops in 10 FSW increments 1.5
  times the original first stop time.
  
• 6. If treatment is at 40 FSW on oxygen, multiply
  the 30 and 20 FSW stops by 1.5.
  
• - If original schedule did not call for a 30 FSW
  stop, use the 20 FSW stop time x 1.5 and take it
  _at_ 30 FSW.

140
Emergency Procedures

• 7. If treatment is at 30 FSW on oxygen, multiply
  the 20 FSW stop time by 1.5.
  
• 8. If asymptomatic upon surfacing, transport on
  O2 to the nearest chamber and treat on a TT-5.
  (This may be waived if chamber is not within a
  reasonable distance (12-24 hrs).
• If symptomatic, transport to the nearest chamber
  and treat on a TT-6.

141
Emergency Procedures

• 9. If a chamber is available on station
• - Diving supervisor may forego in-water
  treatment and surface the diver for treatment in
  the chamber.
  
• -OR-
• - The diving supervisor may elect to leave the
  diver in the water for 30 to relieve the
  symptoms and then surface the diver to the
  chamber.

142
Emergency Procedures

• Diver Remaining in the Water
• 9. (cont)
• In either case, the surface interval should be 5
  minutes or less, and the diver should be
  considered to have Type II decompression
  sickness, even if the symptoms are Type I. After
  completing recompression treatment, observe the
  diver for at least 6 hours. If any symptoms
  recur, treat as a recurrence of Type II symptoms.

143
Emergency Procedures

• Diver Leaving the Water
• If the diver indicates that he has decompression
• sickness and feels he cannot safely remain in
• the water
• 1. Surface the diver at a moderate rate (not to
  exceed 30 FSW/MIN).

144
Emergency Procedures

• Diver Leaving the Water
• 2. If a recompression chamber is on site,
  recompress the diver immediately. Guidance for
  treatment table selection and use is given in
  Chapter 20.
• 3. If a recompression chamber is not on site,
  follow the management guidance given in Volume 5.

145
Questions?
146
02
1000
1002
105
1052107
1115
1118
75
110/80
210
210
02
40
1127
09
1144
15217
1247
155305863
1248
X
248
133
N/A
147
02
1200
108
1202
1226
1082110
1229
26
110/30
256
256
40
1243
14
1244
X
44
18