Exposure limits for air diving operations
Contents
Introduction
1 This diving information sheet is part of a series of information sheets providing guidance on diving at work. It replaces the following diving safety memorandum: DSM 2/1990. The remaining DSMs have either been replaced by other diving information sheets, or will be cancelled when the Diving at Work Regulations come into force on 1 April 1998.
2 The sheet contains guidance on the maximum time that a diver, using air, should spend under water.
Exposure limits for air diving operations
3 HSE's policy is to recommend that diving, which uses air, should be organised in such a way that the planned bottom times* do not exceed the limits outlined in Table 1.
4 If a nitrox breathing mixture is being used, you can find out the maximum exposure by entering the equivalent air depth of the maximum dive depth in the table below.
Table 1 Maximum bottom time limitation for surface decompression, in-water decompression, and transfer under-pressure decompression diving | |||
---|---|---|---|
Depth | Bottom time limits (minutes) | ||
Metres | Feet | Transfer under-pressure | Surface decompression and in-water decompression |
0-12 | 0-40 | 240 | 240 |
15 | 50 | 240 | 180 |
18 | 60 | 180 | 120 |
21 | 70 | 180 | 90 |
24 | 80 | 180 | 70 |
27 | 90 | 130 | 60 |
30 | 100 | 110 | 50 |
33 | 110 | 95 | 40 |
36 | 120 | 85 | 35 |
39 | 130 | 75 | 30 |
42 | 140 | 65 | 30 |
45 | 150 | 60 | 25 |
48 | 160 | 55 | 25 |
51 | 170 | 50 | 20 |
* Bottom time:the total elapsed time from when the diver is first exposed to a pressure greater than atmospheric, ie when leaving the surface, or on the start of pressurisation when a closed bell is employed in the observation mode, to the time (next whole minute) that the diver begins decompression (measured in minutes).
Further reading
- Commercial diving projects offshore. The Diving at Work Regulations 1997. Approved Code of Practice L103
- Commercial diving projects inland/inshore. The Diving at Work Regulations 1997. Approved Code of Practice L104
- Recreational diving projects. The Diving at Work Regulations 1997. Approved Code of Practice L105
- Media diving projects. The Diving at Work Regulations 1997. Approved Code of Practice L106
- Scientific and archaeological diving projects. The Diving at Work Regulations 1997. Approved Code of Practice
- The Diving at Work Regulations 1997 SI 1997/2776 The Stationery Office 1997 ISBN 0 11 065170 7
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This leaflet contains notes on good practice which are not compulsory but which you may find helpful in considering what you need to do.
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Printed and published by the Health and Safety Executive 2/98 DVIS5 C20
Added to the Web Site on 23/9/1998