Safe Diving C
| Checklist |
| Compressors |
| Computers (see Dive Computers) |
| Cylinders |
| Cylinders (Nitrox and mixed gas) |
| Cylinder pressures |
Checklist
The BSAC recommends that divers prepare their equipment by devising and using a checklist.
Compressors
For safety reasons only properly trained and competent people should operate compressors. If you use a portable petrol or diesel engine compressor take care not to have the air intake in a place where fumes may be ingested with the air, and never use the compressor in a site where it is an annoyance to other people. It is essential that air of a high standard of purity is delivered.
The production of compressed air for use in oxygen enriched mixtures requires specialised oil-free equipment and training. Only properly trained operators using appropriate equipment should undertake this.
Cylinders
The current test and inspection specifications (August 2002) approved by the Health and Safety Executive are BS EN 1968 (Steel) and BS EN 1802 (Aluminium). Diving cylinders must be tested according to the aforementioned standards. These standards call for diving cylinders to be visually inspected every TWO & a HALF years and subjected to a hydraulic test every FIVE years. Divers should ensure that test stations carry out their tests in accordance with BS EN 1968 and BS EN 1802 and should obtain a test certificate which states this. Test stations approved by the Inspectorate for Diving Equipment Servicing and Testing (IDEST) are recommended.
(See the IDEST website: http://www.sita.org.uk/idestmembers.html ).
The cylinder should be stamped by the test station after every inspection / test and a label attached to indicate when the next inspection is due. Cylinders to the obsolete specifications HOS, HOT (steel) and HOAL 1, 2, 3, and 4 (aluminium) are still legal for use by divers, although no longer manufactured.
Test standards BS 5430 Part 1 & 3 have been withdrawn.
Cylinders (Nitrox and mixed gas)
Additional to the requirements set out above in the ‘Cylinders’ section, cylinders that are for use with nitrox and mixed gases should be dedicated to this use, marked with a suitable label that clearly identifies the gas mixture contained (oxygen and / or helium percentage) and the Maximum Operating Depth (MOD). This practice should ensure divers do not confuse cylinders and that they breathe the correct gas at the correct time and depth. Cylinder contents should always be analysed at the time of filling and again immediately prior to the dive. The BSAC recommends the convention of configuring the richest oxygen mix gas to the right hand side to assist gas recognition.
Cylinders should be regularly (usually annually) cleaned to oxygen service standard. Oxygen service standard is essential where the oxygen content is 23% or greater and the cylinder is likely to be filled using pure oxygen and the partial pressure method. Nitrox cylinders should have a maximum working pressure of 250 bar.
Cylinder pressures
The dive should commence with sufficient gas to conduct the planned dive in all cylinders including bale out gas.
Cylinder pressures should be regularly monitored throughout the dive and it is recommended that:-
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Open circuit divers return to the surface before pressures have fallen to one third of remaining capacity.
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Rebreather divers should return to the surface before the pressure falls below 30bar in any supply cylinder directly connected to the breathing loop. Rebreather bale out cylinders should be capable of allowing the diver to return to the surface with one third of gas remaining in the cylinders.
Page last modified: 12th Dec 2006 - 15:43:05