DIR standard gases

[lamont]

Still has never made sense to me. 21/35 is not really trying to kill me at 155ft I would us it to 160ft without much concern. If you are doing a tech1 dive and dipping a bit below 150ft its fairly straightforward to average 1.2 And the new hard limit of 150 is <1.4

21/35 is actually 150 fsw +/- 10 fsw, so 160 max with 150 average is 'legal'.

 

[ivobj]

I recently took Tech II with Dan MacKay. Because I had done my Tech I before GUE changed the MOD markings from 1.4 to 1.2 this was something we talked about at length.

Bottom gases up to the Tech II level (PPO2 = 1.2):
- 32% ---> MOD 100
- 30/30 --> MOD 100
- 21/35 --> MOD 150
- 18/45 --> MOD 200
- 15/55 --> MOD 240

Deco gases (PPO2 = 1.6):
- 100% --> MOD 20
- 50% ---> MOD 70
- 35/25 --> MOD 120
- 21/35 --> MOD 190

The way it was explained to me was that GUE had always recommended a 1.2 average and that the only change was that the 1.4 "hard limit" had been removed. Meaning that you could still take the gas to 1.4 as long as you averaged 1.2.

He also told us not to go remarking all our bottles just yet.

Complementing, for botton gases I usually calculate for each dive specifically considering the average 1.2 for ppO2 and AED of 30 mt (~100ft).

For deco I use the standard ones:

- in case of short deco obligation, I usually use only 50%,
- if 2 gases 50% and 100% O2,

I never made deco with more than 2 gases other than back gas, for the deeper dives usually I make the deep deco stops on back gas and change to 50% at 70 ft.

 

[rjack321]

21/35 is actually 150 fsw +/- 10 fsw, so 160 max with 150 average is 'legal'.

Rather unusual to me to have plus or minus around a "MOD". To me its 160ft with some shallower average recommended usage guidelines.