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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