46 CFR Appendix A to Part 197 - Appendix A to Part 197—Air No-Decompression Limits

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Appendix A to Part 197—Air No-Decompression Limits

The following table gives the depth versus bottom time limits for single, no-decompression, air dives made within any 12-hour period. The limit is the maximum bottom time in minutes that a diver can spend at that depth without requiring decompression beyond that provided by a normal ascent rate of 60 fsw per minute. (Although bottom time is concluded when ascent begins, a slower ascent rate would increase the bottom time thereby requiring decompression.) An amount of nitrogen remains in the tissues of a diver after any air dive, regardless of whether the dive was a decompression or no-decompression dive. Whenever another dive is made within a 12-hour period, the nitrogen remaining in the blood and body tissues of the diver must be considered when calculating his decompression.

Air No-Decompression Limits

Depth (feet): No-decompression limits (minutes)
35 310
40 200
50 100
60 60
70 50
80 40
90 30
100 25
110 20
120 15
130 10

(Source: U.S. Navy Diving Manual, 1 September 1973.)