Commercial diving/Operate the Dive Chamber

Relevance: Surface oriented wet bell diving.

Required outcomes:

Demonstrate the ability to prepare the chamber for use
Calculate the appropriate quantity of chamber and BIBS gas for a planned chamber operation
Calculate an appropriate reserve gas supply for a planned chamber dive profile
Assist occupants to prepare for a chamber dive
Demonstrate the ability to operate the gas control valves during a chamber operation
Communicate with other dive team members and chamber occupants using voice communications and hand signals as appropriate
Record the progress of a chamber operation
Clean and prepare the chamber and associated equipment for storage after use
Show the ability to submit defect reports and maintain equipment

Assessment criteria for Chamber Operator practical skills

Assessment Criteria for Chamber Operator Practical and Planning Skills assessment

As a general principle competence in a composite skill implies competence in component skills. RPL assessment should target the composite skill to save time.
All skills must be assessed until each one has been performed competently.
If the assessor has any doubts that a critical skill can be consistently performed the skill should be demonstrated competently 3 times in succession
Several skills may be assessed together when convenient (integrated assessment).
Any practicable combination of these skills may be assessed on a single run.
Whenever practicable demonstration of the skill should be personally observed by the assessor.
Chamber operation skills may be demonstrated on an approved simulator where practicable. A simulator should have a control panel made up from the same type of components as those on a full size chamber, but scaled down to provide realistic flow rates. A simulator may be approved if it provides realistic experience of all the operations it will be used for. (This implies that valve lever angles on the simulator will control flow rates to result in pressure changes that are similar to the changes in a full size chamber for the same valve lever angles. A basic requirement would be that a fully opened supply valve would pressurise the simulator to the same pressure in a similar time and a fully opened exhaust valve would decompress the simulator in approximately the same time as for the full size chamber. The full set of valves and controls is not necessary on a simulator, and lock doors and double chambers are not required, however the valves must operate in the same way [1/4 turn ball valves] and there must be a pressure gauge calibrated in msw and fsw of a similar type to those on a real chamber. A pressure sensor connected to a computer which can graph the profile would be very useful but is not compulsory. A means of recording the profile on a dive computer would also be useful as an alternative)
The candidate must perform competently during at least one full run done on a full size twin lock chamber.

Specific skills listed by category:

Category: Planning

Specific skills

Select Decompression Tables, Plan schedule.
- Select suitable tables suitable for:
  - A training dive to 50 metres
  - Surface decompression on oxygen
  - Surface decompression on air
  - Treatment for decompression illness (recognise that the tables are treatment tables)
  - Precautionary procedure for asymptomatic case of omitted decompression, given the actual dive profile.
- Draw up an elapsed time schedule for a chamber run using the chosen tables. Indicate/explain any additional conservatism applied.
- Draw up a contingency profile to deal with a plausible deviation from the planned schedule
Chamber gas calculations:
- Calculate the amount of air required to pressurize a chamber given the volume of the chamber.
- Express this volume as litres free air and as pressure change (bar) in storage cylinders of specified capacity
BIBS gas calculations:
- Calculate the amount of gas required for a treatment table for one diver given the table and an RMV for the diver.
- Calculate the pressure change in a HP supply cylinder of given volume during the treatment. (pressure change may be spread over more than one cylinder if necessary)

Category: Prepare Chamber for use

Specific skills

Prepare chamber
- Check chamber is safe and ready for use
  - Chamber is in date and suitable for required pressure
  - Interior of chamber is clean, dry, smells OK, no debris/foreign objects lying around.
  - Fire extinguisher is full, in date and in place
  - Exterior of chamber is clean, no damage visible
  - Windows in good condition
  - Valves are in correct status (more detail here?)
  - Oxygen monitor connected and tested, calibrated if necessary
  - Timer ready and working
  - Medical lock closed, seals in good condition
  - Main and fore chamber door hinges and seals in good condition and clean, doors swing easily and seat as intended
- Check main gas supply sufficient, connected
  - LP compressor ready if applicable
  - HP storage pressure and volume sufficient
  - Regulator fitted
  - Regulated pressure appropriate
  - LP whip connected to regulator and chamber, joints tight, no leaks, main and fore chamber filling valves tested, closed and not leaking
Prepare BIBS
- Check BIBS fitted, operating, ready for use
  - BIBS connected to supply and dump lines
  - BIBS tested, clean and disinfected, stored correctly
  - BIBS dump valve open (?)
- Check BIBS gas supply sufficient, connected
  - Oxygen cylinder pressure and volume sufficient for the planned profile
  - Oxygen regulator fitted
  - Regulated pressure appropriate
  - LP Whip connected to regulator and chamber, joints tight, no leaks, valves closed.
Prepare communications equipment:
- Connect power, switch on and test voice comms equipment
  - Comms functions both ways
  - Comms set to monitor chamber
- Emergency comms equipment present and functional
Check chamber lighting functional
- Connect power, switch on, switch off if not needed.
Sign off chamber checklist – ready for use

Category: Pressurise chamber

Specific skills

Initiate compression
- Blow down and establish seal (about 1.5m?)
- Check occupants can equalise (about 9m?)
- Check for audible leaks
Blow down to depth
- Blow down to specified operating depth
  - Maintain rate of 20m/min if possible and no problems arise
- Stop if requested by occupants
  - Delay while ears cleared if required
  - Ascend slightly to facilitate ear clearing if required
- Stop at operating depth
  - Do not overshoot depth
Maintain operating depth
- Correct for cooling (+0m,-1m)
  - Add air to maintain pressure as chamber cools
- Maintain nominal depth +0m, -1m
Vent to provide air changes (keep CO₂ level low)
- Full vent 1 minute in 5 (may be shortened during training to 20 seconds if chamber has no occupants)
- Chamber pressure maintained during venting

Category: Communications

Specific skills

Brief occupants before run (specifically learner divers about to undergo their first chamber dive) (a checklist may be used if available)
- Explain the need for equalising the ears and what to do if there are problems (descent and ascent)
- Explain the planned profile
- Specify the decompression schedule
- Inform the occupants of the need to prevent restriction of circulation
- Answer questions on the procedures
- Explain the communications procedures (voice and emergency)
- Explain emergency procedures
- Check that occupants remove any fire hazards from their person
- Warn occupants to be careful of the BIBS and not to tamper with valves
Authorise entry to chamber
Check function of voice comms with occupants
Check that occupants are able to equalise at start of descent
Inform occupants of immanent changes in pressure and other waypoints in the schedule during the run
Use appropriate voice procedures
- Exchange voice messages using correct voice protocol

Category: Operate Medical lock

Specific skills

Transfer materials into pressurised chamber
- Check that items are suitable for pressurisation (open sealed rigid containers)
- Instruct occupants to check that medical lock inner door is closed
- Check if medical lock is pressurised
  - If so, vent to atmosphere
- Open outer lock door
- Insert items into medical lock
- Close outer door, check vent closed
- Instruct occupants to equalise medical lock
- Compensate main lock pressure if necessary
- Instruct occupants to open medical lock, remove items, close and reseal inner door and close equalisation valve
Transfer materials out of pressurised chamber
- Check that outer medical lock door is closed and sealed
- Check that vent valve is closed
- Instruct occupants to equalise medical lock and open inner door
- Instruct occupants to insert items into medical lock and close and seal door, and close equalising valve
- Open vent valve and check that medical lock vents and does not leak from main chamber.
- Open outer door and remove items from chamber
- Close and seal outer door, close vent valve

Category: Operate fore chamber lock

Specific skills

Transfer personnel into pressurised main chamber
- Brief occupants
- Authorise entry into fore chamber
- Check occupants ready for compression
- Pressurise and check door seal
- Compress to depth of main chamber
- Check chambers equalised and transfer into main chamber
Transfer personnel out of pressurised main chamber and decompress per schedule
- Pressurise fore chamber to main chamber depth
- Instruct occupants to equalise chambers using valve if necessary
- Instruct occupants to transfer to fore chamber and hold door closed
- Get a seal between the chambers by dropping the fore chamber pressure about a metre and pressurising main chamber if required to retain correct depth
- Decompress fore-chamber as required to suit profile of occupants.
- Ensure that pressure history of all occupants is considered.
- Provide BIBS Oxygen as required
- Vent and monitor Oxygen concentration if applicable

Category: Provide oxygen by BIBS

Specific skills

Supply oxygen to BIBS
- Open supply of O₂ to BIBS
- Check BIBS dump open
Monitor oxygen use
- Monitor PO₂ in chamber gas
- Monitor status of occupant on O₂ (via reports from inside tender)
- Record time on O₂
- Control length of oxygen sessions and air breaks
Vent O₂
- Extend venting when PO₂ is too high

Category: Conduct decompression

Specific skills

Monitor time at depth
Record waypoints of profile
Modify decompression schedule to compensate for deviations from planned profile
Start ascent at scheduled time (-30sec+0sec (?))
- Stage decompression
- Decompress at rate appropriate to selected table
- Arrive at stops on schedule
- Maintain correct stop depth
- Leave stops on schedule
Slide decompression
- Conduct slide ascent at correct rate
Vent 1 minute in 5, extend if necessary to control O₂ levels

Category: Manage emergencies

Specific skills

Fire in the chamber
- Explain procedures in case of fire in the chamber
Fire in the control room
- Explain procedures in case of fire in the control room
Loss of pressure
- Explain procedure in case of loss of pressure
Gas contamination
- Explain procedure in case of contamination of
  - Chamber gas
  - BIBS gas
Medical problems
- Explain procedure in case of the following:
  - Tension pneumothorax
  - Oxygen convulsions
  - DCS of inside tender

Category: Secure chamber after use

Specific skills

Debriefing
- Debrief occupants if appropriate (specifically learner divers and divers treated for mild DCI)
  - Occupants are warned of:
    - Repetitive group status (or equivalent)
    - Possibility of DCS symptoms
      - To stay near chamber for recommended period
      - Not to exercise strenuously for period
      - Time to fly restriction (including any major increase in altitude)
Housekeeping
- Check chamber clean, dry and clear of objects brought in by occupants
- Clean and dry as required
Shut down procedures
- Check gas supply closed, compressor shut down etc
- Check BIBS gas supply closed, BIBS clean and stored

Category: Administration

Specific skills

Complete chamber operations record
Record and report incidents and equipment malfunctions

Assessment Criteria for Chamber Operator required range of experience

During a formal training program records of all training runs should be kept on a standard form supplied by the school to keep track of what has been done and so that at any time it is possible to see what must still be done.
A similar form should be used to compile evidence of experience for RPL.
The order of the runs is not important
A run may only be counted for experience if it was performed competently. Runs in which hazardous errors were made must not be logged towards experience but must be repeated until performed competently. Minor errors which are corrected by the learner and do not constitute a significant hazard to the occupants may be disregarded.
There should be at least one run without any significant errors.

Explanation of requirements for specified chamber runs

50msw training dive for 10 minutes bottom time (Table optional, any authorised non-treatment table may be used
- Run chamber with 1 or more occupants for training chamber dive to depth of 50msw
- Planned bottom time to be approximately 10 minutes (may vary if there is good reason)
- Depth may be reduced if limited by maximum operating pressure of chamber, but should not be less than 30msw
- Vent 1 minute in 5
- Decompress conservatively based on greater depth, greater time or both
- Use stops as required by table in use
- Make any corrections necessary in case of depth or time over-runs
- Record run and log operation
Simulated recompression for omitted decompression
- Compress main chamber with occupants playing parts of inside tender and diver with omitted decompression
- Follow omitted decompression procedure according to US Navy Diving Manual or other authorised decompression tables for given scenario described by the instructor/assessor. (USNDM rev.6 Chapter 9, Table 9-3 and paragraphs 12.10.1 to 12-10.3)
SurD O₂ (to USN Rev 5 Table 9-9 or Rev 6 table 9-9)
- Pre-compress main chamber to working depth
- Compress divers in fore chamber to working depth
- Supply Oxygen by BIBS (may be modified as for Oxygen short table for training and assessment purposes)
  - Monitor and control Oxygen times
  - Monitor and control Air breaks
- Decompress according to schedule
- Record run and log operation
SurD Air (to USN Rev 5 Table 9-10)
- Pre-compress main chamber to working depth
- Compress divers in fore chamber to working depth
- Decompress according to schedule
- Record run and log operation
Oxygen short table (USN Table 5) (may be modified as described below for training and assessment purposes. )
- Compress main chamber with occupants playing parts of inside tender and patient
- Use BIBS for at least 5 minutes, thereafter use can be simulated.
- Oxygen intervals (real or simulated) can be reduced to 5 minutes
- Oxygen partial pressure of any chamber with BIBS in use must be monitored and chamber vented to maintain PO₂ remains within specified limits (<25% by volume unless otherwise authorised)
- Decompression to follow Table profile, but stop lengths can be shortened in same way that treatment at max depth was shortened. (oxygen intervals can be simulated and/or reduced to 5 minutes each)
- Slide decompression must follow table requirements
- Record run and log operation
Medical lock transfer IN
- Transfer item/s into pressurised main chamber according to approved procedure
Medical lock transfer OUT
- Transfer item/s from pressurised chamber out according to approved procedure
Fore lock transfer IN
- Transfer an occupant to the pressurised main chamber using the fore chamber
- This may be part of a SurD recompression, or an inside attendant with no decompression obligation
Fore lock transfer OUT
- Transfer an occupant out from the pressurised main chamber. Decompress in the fore chamber as required by the occupant’s pressure exposure history.
- Use an appropriate table to derive the correct decompression schedule
- Use of BIBS in fore chamber is optional
Chamber preparation and Pre-run checks
- Prepare chamber for use
- Complete and record pre-run checklist
- Correct or report any problems
Secure chamber and Post run checks
- Clean chamber as required
- Make up stock of used materials or notify responsible person
- Complete and record post-run checklist
- Report any defects

Assessment Criteria for Assessment of attitudes

Category: Safety

Specific item:

Compliance
- Chamber Operator complies with statutory and organisational safety requirements without having to be constantly reminded (Diving regulations, ACoP’s, Operations manual etc.)
- Chamber Operator reports incidences of non-compliance to the appropriate authority
Situational awareness
- Chamber Operator pays attention to surroundings and appears aware of changes in circumstance which should be apparent.
- Chamber Operator recognises changes in circumstances which may affect team safety
- Chamber Operator alerts team to changes in circumstances that they should know about

Category: Teamwork

Specific item:

Contribution
- Chamber Operator does fair share of work taking physical and other abilities into account
Fitting in
- Chamber Operator acts as part of the team and does not alienate other members
Proactive
- Chamber Operator performs appropriate functions without having to be specifically requested each time.

Category: Communication

Specific item:

Communication
- Chamber Operator is able to communicate effectively with other members of the team
- Chamber Operator communicates when appropriate and provides useful information.
- Information provided is not known to be incorrect.
- Chamber Operator timeously notifies diving team of information that he is required to provide (particularly relating to fitness to dive, hazards, non-compliance with safety requirements and equipment failure, loss and defects)

Category: Timekeeping

Specific item:

Punctuality
- Chamber Operator arrives at arranged times
- Chamber Operator does not unduly hold up proceedings by tardy performance of tasks.
- Chamber Operator gives reasonable warning /notification if not able to meet schedule
Availability
- Chamber Operator remains on site and available for tasks as required according to prior arrangements and standard procedures

Information for Feedback

Written feedback should be appended to the PoE and the basic details logged.
As a general rule there should be written feedback in a situation where remedial work is necessary, or where the learner/candidate must be informed that action outside of the standard programme must be taken. Written feedback must be signed as understood by the learner, and should contain a statement by the learner whether the feedback is accepted as fair or not.
The learner may provide written feedback to the school which must also be appended to the PoE and noted on the record form. The school may append comment on such feedback and should record any action taken as a consequence of such feedback and include this in the PoE, either complete or as a reference to the official report. This is particularly important in the event of claims of breach of standards or unfair treatment.