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Occupational Health and Safety Act, 1993 (Act No. 85 of 1993)

Code of Practice

Diving Regulations, 2009

Code of Practice for Inshore Diving

5. Diving Equipment

5.3 Divers' breathing gas supply


The diving apparatus must be arranged in such a manner that every diver, including the standby diver receives a breathing gas of the correct composition, volume, temperature and flow for all reasonably foreseeable situations, including emergencies.


All divers must receive an uninterrupted supply of breathing gas. In particular, the supply must be arranged so that no other diver (including the standby diver) is deprived of breathing gas if another diver's umbilical is cut or ruptured.


If breathing gases are not analysed immediately prior to use, an incline oxygen analyser with an audible Hi-Lo alarm must be fitted to the diver's gas supply line in the dive control area. This will prevent the diver being supplied with the wrong percentage of oxygen.


5.3.1        Compressors


Compressors used to supply air to divers in the course of a diving operation shall be capable of maintaining a supply of air to meet the air requirements of the diver/s.


All receiver tanks and pressure vessels used in connection with compressors shall meet the required regulations and standards.


Compressors shall be operated by a competent person who, if circumstances permit, may also act as a diver's tender. The compressor operator shall ensure that all equipment necessary to supply an adequate quantity of air to the diver is in good working order. Particular attention shall be given to valves, stop valves, drain cocks, gauges, and all parts liable to be damaged.


5.3.2        Prevention of contamination of breathing air supply


The diving contractor shall ensure that adequate procedures are in place to ensure that compressed air supplied to divers comply with the minimum requirements set out elsewhere in this document. This will include procedures, checklists, maintenance and tests with regards to compressor air intakes, the compressor itself, the filtration systems and any other part of the equipment. Some of these aspects are covered in other Regulations under the Act.


5.3.3        Storage cylinders


Gases stored in cylinders at high pressure are potentially hazardous. The dive plan must specify adequate protection for the gas storage areas. All gases used during diving projects will be handled with appropriate care.


Gas storage cylinders must be suitable in design, fit for purpose and safe for use. Each cylinder must be in date in terms of SANS 10019.


Cylinders used for diving within the scope of this Code may be subjected to special conditions, such as use in salt water, and will therefore need special care. Cylinders used under water in direct contact with the water should be tested according to the requirements for Scuba cylinders, as they are subject to the same environmental conditions.


Detailed requirements are contained in other Regulations under the Act. Contents of gas cylinders


Gas cylinders containing breathing gases coming from suppliers will be colour coded in accordance with industry guidance and will be accompanied by an analysis certificate. Neither of these should be accepted as correct until a competent member of the dive team has analysed at least the oxygen content. This analysis should be repeated immediately before use of the gas.        Marking and colour coding of gas storage


Fatal accidents have occurred because of wrong gases or gas mixtures being used in a diving project.


The diving contractor will ensure that all gas storage units comply with a recognized and agreed standard of colour coding and marking of gas storage cylinders and banks. Where appropriate, pipework should also be colour coded.


Unless special circumstances apply, gas cylinders for inshore and inland operations will be marked and colour coded in accordance with SANS 10019.


5.3.4        Breathing gas composition


Constituent gases for breathing mixtures should be within 0.5% by volume of the nominal composition.        Breathing gas toxicity


Divers breathing a mixture of oxygen and nitrogen under pressure, whether compressed natural air or an artificial mixture, are at risk of both oxygen toxicity and nitrogen narcosis as the depth increases. The dive plan will therefore need to specify the maximum depth for the mixture being used.


The recommended maximum partial pressure range for oxygen used under water is 1.4 bar to 1.6 bar for the working part of the dive. The partial pressure for oxygen used must never be lower than 0.2 bar.


Partial pressure of oxygen during decompression should comply with the requirements of the decompression schedule in use, taking into account the breathing apparatus and security of the diver's gas supply and airway in case of loss of consciousness.


Breathing mixtures other than oxygen and nitrogen (or air) should be used when diving takes place deeper than 50 m of water. Diving at these depths is covered in the Code of Practice for Offshore Diving.        Breathing air purity standards


Breathing air for diving under this Code will comply with the SANS 10019.        Air purity testing


To ensure that breathing air complies with these minimum standards, the diving contractor will ensure that the air is tested in the following manner:

The compressor should have a monthly functionality test for delivery and pressure.
An air purity test must be performed at a maximum interval of 6 months.
An air purity test may be performed more frequently if deemed necessary.
Testing for contaminants other than those listed in the SANS10019 shall be conducted if their presence is suspected.


Quantitative testing for particulate matter (including oil) shall be conducted if its presence is evident in a qualitative test.


A record of these tests should be kept with the compressor log for inspection.        Purity of gases for breathing mixes


These criteria apply equally to the gases in storage and after mixing, before delivery to the diver.


Gases should be tested for specific contaminants when there is reason to suspect that they may be present above the limits. A HIRA survey should be used to determine the likelihood of these or any other potentially toxic contaminants being present in the breathing gas.


Potential contaminants should be limited to:




Carbon dioxide

1000 ppmv

Carbon monoxide

5 ppmv




40 to 200 bar

>200 bar

50 mg/m3 (62ppmv)

35 mg/m3 (44ppmv)

Low pressure: RH ideally 50% to 60%


0,1 mg/m3

Solid particles

0.5 mg/m3 for particles >  5 µm



Volatile hydrocarbons excluding methane

5 ppmv


25 ppmv

Hydrogen sulphide

1 ppmv

Sulphur dioxide

1 ppmv

Oxides of nitrogen

2 ppmv

(Ref: ECHM  Book of Experts Reports, Section 5.1, Table 6: Proposed contaminant units for compressed air).


5.3.5        Oxygen banks and Oxygen installations


Pressurised oxygen can cause a serious fire or an explosion, but can be used safely if stored and handled correctly. Any gas mixture containing more than 25% oxygen by volume should be handled like pure oxygen.


Any components used in plant which is intended to be exposed to high partial pressures of oxygen will need to be cleaned of hydrocarbons to avoid explosions; Formal cleaning procedures for such equipment must be specified by the diving contractor, together with documentary evidence that such procedures have been followed.        Oxygen hoses


The use of hoses for oxygen in lieu of piping shall be kept to a minimum. Hoses and associated fittings shall be constructed of material that is compatible with oxygen at the operating pressure and temperature.        Flow velocity


High flow velocities of oxygen through hoses shall be such that the differential pressure along a hose does not exceed 700 kPa (7 bar)        Valves


Quick-opening valves such as ball valves should not be used in oxygen systems where the pressure exceeds 700 kPA (7 bar)        Oxygen storage area


An area where oxygen is stores shall be:

adequately ventilated;
properly identified with warning signs;
kept clean and located as far as practical from combustible materials


5.3.6 Chambers


All chambers used under this code shall be of a twin-lock configuration and have sufficient space available to treat all the ill or injured divers in an emergency, with at least one ill diver lying in the horizontal position.        Availability of recompression chambers


A recompression chamber is required at the dive site whenever any one of the following conditions is present:

diving takes place at a depth exceeding fifty metres; or
decompression stops are required as part of the dive; or
a functional facility for recompression of a diver is not available within two hours; or
the diving project is an offshore operation


Whenever an onsite recompression chamber is not required in terms of the previous paragraph, arrangements must be made to ensure that all divers could receive recompression therapy within two hours from the time when the need for recompression is identified.


The diving contractor must identify the location of the nearest diving or hyperbaric chamber appropriate for the depth at which the diving operations are to be carried out and make sure it is within two hours travelling time by available transport from the dive site to the diving chamber. The diving contractor will confirm that the decompression facility is in a safe and operational state.        Operation of chambers


Diving chambers may only be operated by persons with the appropriate qualification and competence.


Chamber operators must be available while diving operations are in progress and they must remain on duty at the chamber while the chamber is in use.


Chambers must only be operated using appropriate published or proprietary diving or treatment tables. The tables to be used mus be contained in the operations manual and be available at the chamber.


Whenever deviation from treatment tables is contemplated, it should be accompanied by appropriate instructions provided by the level 2 Designated Medical Practitioner and approved by the diving contractor. If such instructions are given telephonically it should be co-signed by at least two individuals.


5.3.7 Electrical power Primary electrical power source


The diving contractor shall ensure that the primary source of electrical power for the diving system complies with the relevant regulations.        Alternative power sources


The diving contractor shall ensure that there is a secondary source of power for the diving system in the event of failure of the primary source. The second power source shall be capable of meeting the requirements of the diving system. This may include the following when applicable:

being rapidly brought online;
operating the handling system;
heating the diving plant and equipment, including providing heat for a diver(s) in water;
sustaining life-support systems for compression chambers and any diver in the water;
illuminating the work site of divers and the interior of compression chambers, dive stations, etc.; and
operating communication and monitoring systems.        Electricity used underwater


Divers, and others in the dive team, may be required to work with equipment carrying electric currents, which present the risk of electric shock and burning. The diving contractor shall ensure that the equipment and procedures do not endanger the health and safety of any person.


Recharging lead-acid batteries generates hydrogen that can provide an explosion hazard in confined spaces. Care will need to be taken to provide adequate ventilation.