U XVal-He-4B: A Maximum Permissible Tissue Tension Table for Real- Time Thalmann Algorithm Support of Constant 1.3 ATM PO2-in-Helium Diving to 200 FSW

摘要

The Thalmann Algorithm parameterized with the XVal-He-4 Maximum Permissible Tissue Tension (MPTT) table is a candidate real-time algorithm for use in the Navy Dive Computer (NDC) to support MK 16 MOD 1 He-O2 diving to maximum depths of 200 fsw. However, XVal-He-4 was developed specifically to generate the U.S. Navy Diving Manual MK 16 MOD 1 He-O2 decompression tables to 200 fsw, and not for real-time applications. The XVal-He-4-Thalmann Algorithm can prescribe infinite-duration decompression stops following bottom times of more than a few minutes at depths greater than 211 fsw. Therefore, an NDC implementation of XVal-He-4 could fail to provide decompression guidance with even a brief unplanned excursion deeper than 211 fsw. A modified MPTT table, lacking the problematic 5-minute half-time compartment, was designated XVal-He- 4B. XVal-He-4 and XVal-He-4B produce identical decompression schedules at depths of 180 fsw or less and schedules with practically equal estimated risks of decompression sickness at 190 and 200 fsw. XVal-He-4B does not fail in the operational depth range of the MK 16 MOD 1 and is recommended for use in an NDC to support operations to 200 fsw.