Empirical Evaluation of the MK 16 MOD 1 UBA Breathe-Down Procedure

摘要

Guidance for using new helium-oxygen (Me-C2) decompression tables for the MK 16 MOD 1 underwater breathing apparatuS (UBA) includes recommended performance of a predescent breathe-down procedure (SOP) to reduce descent- induced overshoot of diver-inspired oxygen partial pressure (002). This report describes work completed at NEDU to test the efficacy of this procedure. Thirty- two MK 16 MOD 1 Me-C2 man-dives to 300 feet of seawater (fsw) were completed in the NEDU Ocean Simulation Facility: 16 with descent preceded by performance of the SOP, and 16 without EDO before descent. Diver-inspired 002 was measured with an O2 fuel cell positioned in the base of the inhalation hose on the USA, and with mass Spectrometric analysis of a gas stream sampled from the same site. Peak 002 after descent at a mean rate of 60 fsw/min was not significantly different between SOP (1.92 ATA) and Mo-SOP (1.91 ATA) groups (P = 0.61). It is recommended that the SDP be removed from standard operating procedures for MK 16 MOD I diving. Two OCS incidents in 12 dives completed with the 300 fsw/lOmin schedule from the MK 16 MOO 1 Me-C2 tables motivate a recommendation that a MS 16 MOD 1 Me-C2 diver who has not completed prior work up dives should use the decompression schedule for his actual or planned bottom time at the next tabulated dive depth deeper than his actual or planned dive depth if the latter is greater than 200 faw.