UTD STANDARD MIXES

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 Mix

 Depth Range  MOD  END at Max Depth EAD  "Air Top" Mixing
EAN32  0 - 100'  111'  -  20% credit  14% O2
 25/25  100' - 130'  151'  88'  10% credit  12% O2 - 25% HE
 21/35  130' - 160'  190'  98'  0%  9% O2 - 35% HE
 18/45  170' - 200'  220'  94'  0%  8% O2 - 45% HE
15/55  210' - 240'  275'  90'  0%  7% O2 - 55% HE
 12/60  250' - 300'  352'  100'  0%  5% O2 - 60% HE
 10/70  310' - 360'  429'  88'  0%  4% O2 - 70% HE
 Deco Mix Depth Range   MOD END at Max Depth   EAD "Air Top" Mixing 
 O2  20'  20'  -  - O2 
 EAN50  70' - 30'  70'  -  - 36% O2
 35/25  120' - 80'  120'  -  -  25% O2 - 25% HE
 21/35  190' - 130'  190'  -  -  9% O2 - 35% HE

 


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