Diving with a Closed Circuit Rebreather Diver

Diving with a Closed Circuit Rebreather Diver

As the club evolves there will be divers who will take their diving beyond the basic open circuit single cylinder no-decompression diving. They will move on to Extended Range Diving (ERD) and Closed Circuit Rebreather (CCR) diving. These types of diving involve different techniques and styles of diving. To help the club's divers get a better understanding I will post some useful links and information in this section on rebreather diving.

 

How a rebreather works:

http://en.wikipedia.org/wiki/Rebreather

 What you need to know about diving with a rebreather buddy:

http://www.divernet.com/cgi-bin/articles.pl?id=5221&sc=&ac=d&an=

What can happen when it goes wrong:

http://www.hse.gov.uk/diving/video/co2video.htm

CFT Rebreather Safety Recommendations (from www.CFT.ie)

 The following recommendations have been produced in a bid to promote the safe integration of Semi Closed and Closed Circuit rebreathers within the club and C.F.T. as a body. The most important thing that must be remembered is that no matter how well qualified a diver is on open circuit, a new rebreather diver becomes a diver under training and must again build and practise skills progressively, and be fully aware of all the dangers involved in going beyond the limitations of theirtraining and experience. All diving activities expose us to an element of risk and rebreather diving increases that risk, therefore it must emphasised very strongly that the guidelines laid down by the manufacturers and C.F.T. must be adhered to rigidly when diving a rebreather. 

Rebreather Divers 

C.F.T. prerequisites for rebreather training are minimum Club Diver, Rescue Diver, Extended Range Diver or international equivalents recognised by C.F.T.  The types of rebreathers currently approved for use by C.F.T include 1)      A.P.D Inspiration – classic2)     A.P.D Inspiration with vision electronics3)     A.P.D Evolution4)     Drager Dolphin   All training must be completed by a recognised Technical Training Agency (C.M.A.S, I.A.N.T.D , T.D.I , P.S.A, I.T.D.A or B.S.A.C). On completion of the course the diver should register their qualification with Head Office. 

Skills Practice 

A rebreather diver should regularly practise skills taught on their rebreather training course. Most importantly, shut down, gas switch i.e. bail out skills.     

Pre-Dive Checks 

Pre-dive checks should be conducted in accordance with the unit specification and training, this includes breathing from the unit for at least two minutes before entering the water.   

Cylinder Pressures 

The same rules apply to rebreathers as with open circuit scuba equipment. The dive should begin with a  sufficient amount of gas in all cylinders to carry out the planned dive. Divers shall return to the surface with sufficient reserve in accordance with unit specifications and manufacturers recommendations. Contents gauges and pPO2 levels should be regularly monitored throughout the dive.

 Buoyancy 

Rebreather divers must ensure that they have sufficient buoyancy to support them on the surface and at depth with full configuration of kit i.e. redundancy cylinders etc. Sufficient redundancy must also be considered in the event of a flooded breathing loop. 

Buddy Diving 

It is recommended that while a rebreather diver builds up experience on their unit (at least 100 hours dive time), their buddy should be at least an experienced club diver.It is important to ensure that the buddy of a rebreather diver is familiar with the unit so that in the event of a problem the buddy can assist their partner. Although not essential, it is preferable if the buddy has trained as a rebreather diver or has completed the try dive on the unit in a swimming pool.Proper buddy checks on gas and pPO2 levels must be maintained throughout the dive     

Breathing 

It is strongly recommended that rebreather divers breathe freely and normally, i.e. keep the flow going in the loop, this will increase the CO2 scrubbing and help to avoid hypercapnia. 

Alternative Gas Source 

It is recommended that all rebreather divers should carry sufficient open circuit gas to allow a safe return to the surface in the event of a complete rebreather failure.An open circuit regulator may be connected to the oxygen cylinder of a Closed Circuit Rebreather. If one is attached then the second stage must be clearly marked and have an isolator device fitted, i.e. slider shut off valve or similar.Gas supply should be worn on a “rich right” and  “lean left” basis. 

Diluent Gas 

The diluent gas may be air, nitrox or a helium mix (depending on a diver’s qualifications and the rebreather type)Air diluents should not be used below C.F.T’s maximum depth recommendations or in accordance with the diver’s qualifications (whichever is the shallower)  

Oxygen Gas 

All oxygen used in rebreathers should be of the correct breathing grade. 

Descent 

The recommended set point of O2 must be set prior to entering the water, and again on reaching target depth when diving CCR. When diving with a rebreather, in order to prevent task loading and oxygen spiking it is important that the descent is done slowly.  

Bubble Check (Leak Check) 

Bubble checks must be performed to identify any source of leakage and must be carried out no deeper than six metres. Note: Semi closed rebreathers will emit a trickle of bubbles throughout a dive.  

Ascent 

As with scuba, the recommended rate of ascent is 10 metres per minute.A slow controlled ascent is important in order to avoid a drop in the pPO2 in the breathing loop, which can cause hypoxia. (CCR only)It is also important to allow proper venting of the breathing loop in order to avoid becoming positively buoyant.  

Delayed Surface Marker Buoy 

C.F.T. recommend that an S.M.B.  be carried by all rebreather divers (two for extended range dives one red and one yellow) Boats cannot track bubbles, so the deployment of an S.M.B. is a clear indication of position and intent to surface.The S.M.B. if possible should have an independent means of inflation. 

Repetitive Diving 

It is important for rebreather divers that particular attention is taken regarding their O2 uptake. It is essential to ensure that the National Oceanic and Atmospheric Administration’s oxygen exposure table is strictly adhered to as with Nitrox Diving. 

Cover Divers 

It is recommended that divers covering rebreather divers  be familiar with rebreathers. It is also recommended that they be qualified to at least Club Diver level. 

Dive Planning and Organisation 

When a rebreather diver(s) is in the group it is very important that the dive plan and emergency plan are gone through thoroughly so that in the event of an accident/incident everyone knows exactly what to do. This should be normal practice but more attention is required because of the nature of thegroup.   

Stage Decompression 

Stage decompression diving should not be practised unless the diver has completed C.F.T.’s Extended Range Diver course or  a recognised equivalent.If stage decompression is planned it must be carried out using a recognised decompression computer and/ or decompression software.The diver must have a bail out plan and carry with him an adequate bail out supply of gas to enable him to cope with any foreseeable emergency situation that may arise.This type of diving should be carried out in accordance with Extended Range guidelines. 

Dive Site 

Diving involving hard work by the diver i.e. heavy seas, strong tidal conditions must be avoided by rebreather divers. This is because of the danger of a CO2 build up in the breathing loop of the unit. 

Boats 

When covering divers on rebreathers the boat cox’n must pay particular attention when manoeuvring the boat as rebreather divers produce very few bubbles if any. Rebreathers are “Life Support Equipment” and must be treated with respect on the dive boat. 

Care and Maintenance 

Particular attention must be paid to O2 cells. It is important that these must be dried off, removing any condensation build up after every dive. The manufacturer's recommendation regarding the changing ofO2 cells at intervals must be followed.  

CO2 Absorbent material 

It is imperative that the manufacturer's recommendation regarding the type of absorbent material and duration is followed to the letter. 

Hygiene 

It is important to disinfect the breathing loop in accordance with the manufacturer's recommendations using the proper solution.The breathing loop must be thoroughly washed and disinfected after each use to avoid lung infection.  

Rebreather use during courses and tests 

Rebreathers can be used in all C.F.T courses and tests (except rescue tests) by either the instructor and / or candidate, provided both parties consent. This should be arranged in advance of the course/ test.If a candidate in any way feels intimidated by an instructor using a rebreather during a test, then the test should be carried out on open circuit.

Safety Officer's Report 2007/08

Safety Officers’ Report May 2007 – April 2008

 Prepared by: Bryan Curley, Safety Officer, UCD SAC

Date: 07/04/2008 

Summary:

  The 2007/08 season has passed out with few incidents but did include a couple that were serious with a real risk of injury or death. These incidents serve to remind us that SCUBA diving is an adventure sport with inherent dangers and that we can never become complacent while undertaking club activities.  All incidents were dealt with in a competent and comprehensive manner by the divers on site and were all therefore resolved satisfactorily.  UCD Sub Aqua Club has always prided itself on the way it carrys out all it’s activities correctly and safely. On occasion things will happen no matter how much you do and the club members have the knowledge and training to deal with these situations. We do it by the book and that keeps us and our fiends safe.   

Incidents:

 There were s number of incident reported to the safety office in the past year and a number in which the safety officer was directly involved (these are the ones that still need incident reports to be written). A number of the incidents early in the season were due to poor buoyancy control high lighting the need for all dive leaders to be conscious of their buddy’s buoyancy and dive skill level. Especially early in the season there is a heightened risk of buoyancy control being lost on the ascent from a dive leading to a uncontrolled and rapid ascent.  In addition to the SCUBA incidents there were a couple of incidents on snorkels which remind us that snorkelling must be taken seriously as there are a number of inherent dangers to this activity.  In November of 2007 there was an incident on a club weekend that had nothing to do with diving. A number of club members were assaulted while leaving a disco on the Saturday night during a club weekend. This attack was unprovoked and just points out that it is a rough world out there. We cannot guard against everything so we need to stay alert for trouble and steer clear as well as we can.  

Training:

The major incident in October was very well handled and reinforced the need to continuously train to deal with a crisis scenario. On this occasion we had a boat well stocked with well trained divers who were able to respond to the incident and provide support and assistance to the Diver Emergency Responders (DER) treating the casualty. This may not always be the case and possibly, as in this case, one of the divers you would expect to deal with the incident, may be the casualty.  The DER course is open to all divers and snorkellers irrespective of grade in the club and as such everyone should be doing this course as soon as possible in their diving career. Also those who have done the course or it’s equivalent have an duty to ensure they stay current on the techniques and procedure by taking at least the practical side of the course on a yearly basis. Even if you are not the DER responding to an incident if you have the training you can offer assistance where needed or at least know what is going on.  A lot of people are tempted to throw our eyes up to heaven when out on the boat and another leading diver “incident” is being run thru. These “incidents” serve a very valuable purpose because when it goes bad, it goes bad fast and you don’t have time to think. The responder must rely on the ingrained processes and procedures learnt in the “incidents”. The “muscle memory” required is learnt this way and in a real incident will save time and ultimately prevent serious injury or loss of life. So when there is an “incident” on the boat all divers should watch, learn and get involved.  

Reports:

Date	Incident Ref	Diver(s) Involved	Nature of Incident
1/6/2007	02/2007	Ian Miller	Uncontrolled ascent
3/6/2007	03/2007	Claire Westbrook	Uncontrolled ascent
4/6/2007	04/2007	Katie Maguire	Regulator letting in water
7/6/2007	05/2007	Bairbre Mullee	Trapped on snorkel duck dive
16/6/2007	06/2007	Multiple	Boat Engine Failure
12/8/2007	07/2007	Bernard Brady	Missing Diver
13/10/2007	08/2007	Jenny NiMhurchu	DCI
23/3/2008	01/2008	Sorcha O’Driscoll	Cold Snorkeller – Hypothermia risk

The detailed reports are available in the Members Only section of the web site.

Recommendations:

 Buoyancy control:

Proper buoyancy control by divers of all level is essential to ensure that a dive is completed safely. All should strive to master their buoyancy and be aware that this skill must be constantly practised. There is no magic way to prefect it, it is all about practise. To make buoyancy control easier all divers must ensure they are suitably weighted and familiar with their buoyancy devices. They should also remain aware of their situation to ensure they have their buoyancy under control before it is lost beyond a recoverable state.     

Dive Knife:

All divers and snorkellers must carry a cutting instrument such as a knife or shears in case of entrapment in line. You cannot breather water so if you become entrapped you need a way to release yourself before the air in your lungs or cylinder runs out.  

Briefing:

The DOD is not giving the dive brief because they like the sound of their voice. All divers have a responsibility to listen to the brief and note the DOD’s instructions on what is to be done in a particular scenario such as losing a buddy or a missing diver, etc.  

DER Training:

All divers should ensure they have taken the DER course and make sure they remain current on the techniques and procedures.  

Serious Incident Response Protocol:

The club is developing a Serious Incident Response Protocol (SIRP) to ensure news of a serious incident is communicated to the appropriate persons and provide support to the casualty’s next of kin. A copy will be available as soon as the safety officer finishes writing it and has it approved.

UCDSAC Safety Statement

Introduction
UCD Sub Aqua Club (UCDSAC) is affiliated to C.M.A.S. (Confederation Mondiale des Activities Subaquatiques) or, the World Underwater Federation, through the national federation, C.F.T (Comhairle Fó Thuinn) also known as the Irish Underwater Council. The primary function of these bodies is to promote and advance underwater swimming and related activities, and to formulate, administer and implement the standards, rules and recommendations required for safe diving. The Technical Commission of CFT is elected each year by the member clubs and its function is to maintain safe diving standards.

The function of UCD Sub-Aqua Club is to train its members to the highest standards of competence and safety in snorkelling, diving and boat handling and to instil an attitude of safety first in all instances. All diving related activities, carried out by the club, are governed by the rules and recommendations of the above federations and all training and qualifications are administered by CFT.

The Committee
UCD Sub-Aqua Club is run by a committee of members elected each year at the AGM. The members of this committee most concerned with the safety aspects are:

• The Diving Officer (D.O.)
  All matters relating to diving activities are under the control of the D.O. He/She must necessarily be an experienced diver of 3* grade or higher (see below)
• Safety Officer
  The Safety Officer deals with all issues relating to safety, whether diving or otherwise, associated with the activities of the Club
• Equipment Officer
  He/She ensures that all club equipment is in safe working order
• Boat Officer
  He/She maintains and services the club boat/s
• Captain
  Overall coordination of committee activities

It should be noted that: EVERY MEMBER OF THE CLUB IS RESPONSIBLE FOR THEIR OWN SAFETY AND THE SAFETY OF EVERY OTHER MEMBER OF THE CLUB AT ALL TIMES

UCDSAC conditions of membership
Medical fitness to dive:
As per the CFT requirements, a diving medical examination is required before commencement of dive training, to be carried out by a registered medical practitioner.

On first medical

Chest X-Ray required

Additional medicals

Every five years for divers under 35 years or / if clinically indicated
Every three years for divers over 35 years
Every year if the diver is on long term medication
Or if there is a change of medical status

E.C.G.

at age 50 then every 5 years

For insurance purposes a medical disclaimer to be signed each intervening year and counter signed by the club D.O. with proof retained in Diver’s Log Book.
Additional membership conditions are as per the UCD Athletic Union Council requirements.

Training
UCDSAC facilitates divers from the basic grade upwards and trains divers to Diver 2 star level in house. Training for further qualifications is undertaken on a regional basis directly with CFT.

• Diver 1 Star Qualification
  Training takes place during the academic year, generally between October and March. Training comprises lectures and pool based training including snorkel and scuba training. All training is carried out by suitable qualified instructors. Candidates must be over 16 years of age and in good health (see above).

  Entry requirements

  • Swim 200m freestyle without stopping
  • Swim on back for 50m
  • Hold breath underwater for 30 seconds within 5 minutes of 1&2.
  • Pass diver medical as set out by CFT medical form.

  Pool Training
  Before commencing any open water diving all members of UCD Sub Aqua Club must undergo an extensive training program as laid out by CMAS. The primary training course is known as diver 2 star training programme and subsequent training is an extension of this intensive introduction. The course in snorkelling and diving involves in-water (swimming pool) instruction in the use of fins, snorkels, masks and basic snorkel techniques, as well as techniques in the safe use of underwater breathing equipment known as SCUBA (self contained underwater breathing apparatus).

  Lectures
  The second major element of the course is a series of lectures which are required to understand the various techniques and safety procedures which are necessary for safe diving underwater. The lecture course is divided into 4 main sections and there are 22 separate talks. The sections are dive physics, physiology, equipment and techniques.

  Open Water Diving
  To qualify from this course a prospective diver must pass a number of tests:

  • Written test
    This is conducted at the end of the lecture series and tests a candidates understanding of the material contained in lectures.
  • Pool test
    This tests the candidates proficiency in the techniques and skills learned in the pool

  Only after successfully passing these tests can a candidate proceed to Open Water Diving. After completing 5 dives with instructors to depth not greater than 10m and demonstrating a series of techniques underwater the candidate will be issued with a trainee diver certificate ( 1*). This allows candidates to dive to progressively deeper depths (max 30m) with divers of grade 2* or above.

• Diver 2 Star Qualification
  When candidate has completed 20 dives in Irish waters and has demonstrated, to the satisfaction of the club D.O. a high level of competence in diving techniques, CPR (Cardio Pulmonary Resuscitation) and the ability to lead dives safely, the candidate may be recommended for the diver 2* test.
  This test is conducted by an instructor from another club within CFT and covers all aspects of the course as well as navigation on dives and the ability to lead dives. If passed, the 2* diver is qualified to dive with any diver 1* or above at the discretion of the club D.O.
  Once a diver has qualified as a 2* he/she is then encouraged to continue training and augment existing qualifications by obtaining the following certificates, the training for which is provided on a regional basis:
  
  • Motorboat Handling Certificate
  • V.H.F. Radio Users Certificate
  • C.P.R. and O2 Administration Certificate
  • Rescue Diver Certificate
  • Nitrox Diver
  • Nitrox Blender
• Further Training
  All of the above qualifications with the exception of the Nitrox Diver and Blender qualifications are necessary pre-requisites for the CMAS diver 3* programme. The 3* qualification is the highest diving certificate issued by CFT (subsequent qualifications are instructor orientated) and as such is very important and difficult to obtain. Qualified 3*s also known as Leading Divers have demonstrated an extensive knowledge of all diving related issues as well as the ability to organize groups of divers for safe and enjoyable diving. UCD Sub Aqua Club actively promotes its members, in the interest of safety, to aim towards this qualification. It is also required for the Club Diving Officer to be of this grade at least.

Diving
Scuba diving is undertaken regularly between March and October each year (in season) and occasionally out of season. All members must undertake three 30 minute snorkels at the beginning of each season in order to acclimatise, if they have not dived in an intervening 90 day period. Diving is at the discretion of the Diving Officer and all divers are subject to the (depth) limitations of their diving grade.

• Air
  Divers diving on air are limited to the depth and time as ascribed by the relevant dive tables.
• Nitrox
  Divers must be 2 Star grade or higher to undertake Nitrox training. Divers on Nitrox are limited to the time and depth as ascribed by the relevant dive tables.

• Air and Nitrox Compressors
  UCDSAC provides air and nitrox for all club members. We use two compressors, one fitted with (removable) blending equipment; each is used and maintained to the manufacturer’s recommendations. Members are trained in the use* and care of the compressors before use.
• Buddy System
  Divers must never dive alone. This is the cornerstone of safe diving. The Buddy System ensures that divers are paired with respect to abilities and qualifications and that during diving pairs remain in close contact in order to be of assistance to one another in the event of an incident. The foundation of the Buddy System is the Buddy Check where pairs check and familiarize themselves with their buddies equipment and discuss and agree a dive plan. A Buddy Check is performed before each dive.
• Dive Tables
  Dive tables are used by divers to avoid decompression sickness (DCS), CFT recommends the use of the Buehlmann Air Dive Tables. The version of the Buehlmann Dive Tables used by Irish Divers was developed specifically for sports divers form a system, which is used for professional, mixed gas and caisson diving. The version has less than a 1% failure rate when used correctly. All the empirical factors used in the tables were derived experimentally by the Hyperbaric Physiological Laboratory in Zurich, Switzerland, and tested in water using ordinary sports divers.
• Use of Boats
  The use of boats on open water is an integral part of diving and greatly enhances the Safety of operations, however, boats also introduce certain hazards and an understanding of these and proper training is vital to Safe Diving. At all times while used for diving operations or otherwise Club Boats must be under the control of a qualified Coxswain (Cox’n). A qualified Cox’n is a person who has successfully undertaken and passed the CFT Boat Handling Course.
• Dive Planning
  All dives are planned by a suitable qualified diver or a diver in training, under the supervision of a suitably qualified instructor. Dive planning includes the use of sea charts, weather forecasts and local knowledge to ensure safe diving. In addition, emergency plans are drawn up to identify key emergency services, contact details and access and egress from dive sites. In addition, where practical, any qualified Rescue Divers and Diver Medics are identified and an emergency vehicle with first aid and oxygen is designated.