standard_gases.md

Standard gases

Because you can choose from lot of combinations, we provide list of common gases. Some agencies (GUE, UTD) limit number of used gases and promote their list of mixes called Standard gases. Standardization of gases simplifies logistic, team planning and prevents mistakes during dive. Even you are able to define your custom mixture, because of practical reasons it is preferred to use the same gases within the team over custom gases or different gases for each diver.

• GUE and UTD both use:
  • 1.4 max PpO2
  • 1.2 ppO2 at working depth
  • decompression ppO2 1.6
  • Both Oxygen and nitrogen as toxic
  • Maximum narcotic depth 30 meters (100 ft)

Source:

• GUE standard gases
• UTD standard gases

Metric

Bottom mixes

Gas	UTD Range used [m]	GUE Range used [m]	MOD [m]	MND [m]
EAN 32	0 - 30	0 - 30	33	30
Helitrox 25/25	30 - 39	-	46	26
Helitrox 21/35	39 - 48	30 - 45	57	29
Trimix 18/45	51 - 60	45 - 60	66	28
Trimix 15/55	63 - 72	60 - 75	83	27
Trimix 12/60	75 - 90	-	106	30
Trimix 12/65	-	75 - 92	106	27
Trimix 10/70	93 - 110	92 +	130	26

Note: The MND is shown for UTD maximum depth for each range.

Deco mixes

Gas	UTD Range used / GUE Range used [m]	MOD [m]
Oxygen	0 - 6	6
Ean50	9 - 21	21
Helitrox 35/25	24 - 36	36
Helitrox 21/35	39 - 57	57

Note: MND here isn't relevant, since it is always lower than 30 meters (100 ft).

Imperial

Bottom mixes

Gas	UTD Range used [ft]	GUE Range used [ft]	MOD [ft]	MND [ft]
EAN 32	0 - 100	0 - 100	110	100
Helitrox 25/25	100 - 128	-	150	85
Helitrox 21/35	128 - 157	100 - 147	187	96
Trimix 18/45	167 - 197	147 - 197	216	92
Trimix 15/55	207 - 236	197 - 246	272	88
Trimix 12/60	246 - 295	-	348	100
Trimix 12/65	-	246 - 302	348	88
Trimix 10/70	305 - 360	302 +	427	85

Note: The MND is shown for UTD maximum depth for each range.

Deco mixes

Gas	UTD Range used / GUE Range used [ft]	MOD [ft]
Oxygen	0 - 20	20
Ean50	30 - 70	70
Helitrox 35/25	80 - 118	118
Helitrox 21/35	128 - 187	187