Safe Diving Practices M
Medical examination
Divers should ensure they are fit and healthy to dive and diver training or diving must not be undertaken until the diver has completed an annual medical self-declaration form on renewal of membership. If the diver has no underlying medical condition that would potentially prevent them from diving safely, they may sign the form and a copy should be retained in branch records. If a member has an underlying medical condition or query, telephone contact should be made with a medical referee for further advice. (Forms and medical referee list available from BSAC HQ or can be downloaded from the BSAC website). Branch Diving Officers should ask for proof of current self-declaration status when members transfer to them from another branch.
If any member has been the subject of a decompression accident they must not commence diving again until medical clearance has been obtained from a UK Sports Diving Medical Committee approved referee.
Some countries have local regulations that may require a medical examination so it is worth checking before travelling and diving abroad.
Potential new members who are undergoing the 'Try Dive' or other introductory course should be asked to sign a disclaimer, which states they have not suffered from diseases or conditions which would make aqualung diving hazardous. An example disclaimer can be obtained from the BSAC website at http://www.bsac.org/uploads/documents/Forms/trydivediscl.pdf
Mixed gases (Technical diving)
The terminology ‘mixed gases’ can encompass many types of gases a diver could breathe during a dive. However, it is generally accepted that the main gas used is tri-mix. Tri-mix contains oxygen, helium and nitrogen in various percentages. The amount of oxygen in the mix is reduced the deeper the dive. This is to reduce the effects of high partial pressures of oxygen and to ensure the diver does not suffer from oxygen toxicity. The nitrogen percentage is also lowered to reduce the effect of nitrogen narcosis. Once the percentages of the oxygen and nitrogen have been calculated the balance gas added is helium.
Tri-mix containing less the 17% oxygen percentage at the surface, i.e. a hypoxic mix should not be breathed on the surface or in shallow water. Divers using mixtures unable to support life at the surface are required to carry additional travel & decompression mixes and switch mixes at the appropriate depth.
The BSAC recommends that mixed gas diving should be to a maximum depth of 80 metres and that all participating divers should hold a suitable qualification from one of the recognized training agencies and register this qualification with the BSAC. All divers should be aware that mixed gas diving, with its greater depths, increases the element of risk. It is important that divers are not only suitably trained and qualified but gain depth experience and dive fitness in a progressive way.
Multiple dives (Technical diving)
Technical divers should always track their oxygen uptake. When conducting multi-day diving, it is essential to ensure that the NOAA (National Oceanic and Atmospheric Administration) oxygen exposure limits for both the short term (ie. central nervous system) and long term (ie. pulmonary toxicity) implications are observed. The BSAC recommendation is one deep dive in a 24-hour period.
Page last modified: 18th Dec 2006 - 11:33:11