Overview

To keep our dives consistent, flexible and as simple as possible, we use standardized mixes.  Each mix allows us a range of depths to explore and provides a similar decompression.  This eliminates the need to remember a bunch of numbers and the use of decompression tables, since the ascent profiles are consistent within the mixes.  In other words, a dive to 150' using 21/35 will have a similar ascent profile as a dive to 200' on 18/45.  The primary difference is we'd simply add a 2nd decompression gas (O2) on the 200' dive.


Parameters

  • Bottom mixes have an MOD PPO2 of 1.4 ata
  • ​​Bottom mixes have an average PPO2 of 1.2 ata for our working depth
  • Bottom mixes have a buffer from our working depth and the MOD of 1.4
  • ​Bottom mixes are created by adding HE, then topping with 32% (easy for banking 32% and doing trimix fills) or by quick formulas for "air tops"
  • ​Deco mixes have an MOD PPO2 of 1.6 ata
  • ​Deco mixes have an average PPO2 of 1.2 ata (averaged over the range the deco mixed is used), except for O2 at 20'
  • ​Deco mixes are used over an average of 5 10' stops, except for when using O2 for decompression
  • ​​The higher the HE content, the better, however the HE content must always be enough to provide an END of 100' or less, based on the conservative formula; END = (1 - HE)*ATA's.  This formula assumes O2 to be narcotic


BOTTOM MIXDEPTH RANGEMODEND AT MAX DEPTHEAD"AIR TOP" MIX
EAN320 - 100'100-20% credit14% O2
25/25100 - 130'151'88'10% credit12% O2 - 25% He
21/35130 - 160'190'98'0%9% O2 - 35% He
18/45170 - 200'220'94'0%8% O2 - 45% He
15/55210 - 240'275'90'0%7% O2 - 55% He
12/60250 - 300'352'100'0%5% O2 - 60% He
10/70310 - 360'429'88'0%4% O2 - 70% He
DECO MIXDEPTH RANGEMODEND AT MAX DEPTHEAD"AIR TOP" MIX
O220'20'--O2
EAN5070 - 30'70'--36% O2
35/25120 - 80'120--25% O2 - 25% He
21/35190 - 130'190'--9% O2 - 35% He

UTD STANDARD MIXES