nyresq
Contributor
Putting a nitrox mix in it now sets an MOD (maximum operating depth) within rec limits that CAN NOT BE VIOLATED. People have died breathing the wrong mix for their depth. As stated prior "its just for a few breaths" can throw you into a siezure from a cns hit. Because it won't be "just a few breaths" if you need to go to your bail out bottle. The Sh3t hits the fan, you WILL start breathing harder and you will lower your resistance to a cns hit while trying to get out of trouble. A ppo2 of 1.6 or 1.7 is ok if your just cruising along at a nice comfortable pace and are relaxed. but get excited and flustered and all of a suden that quick hit of a rich mix will throw you into a siezure, and then its goodnight... forever.
fill it with air and you're good to a MOD of 220'. and you can get it filled anyplace you go, you won't need to worry about getting it filled at a local shop on a boat or at the quarry etc...
As far as deco, you've already said you're using an air (21%)computer, so there is no problem with nitogen loading/off gassing computations being different than your backgas.
You've already said this is strictly a bail out/ run for home pony, but IMO I think 13 is too small. At 120' 13 cuft will not last very long. Do a search on pony size and read a few threads on this. I remember one of the threads had calculations worked out for size vs depth vs time needed to surface safely. you might be quite suprised how little time a 13 cuft will last at depth. For the extra gas I think a 20 cuft is worth the small (couple of inches length) increase in size.
fill it with air and you're good to a MOD of 220'. and you can get it filled anyplace you go, you won't need to worry about getting it filled at a local shop on a boat or at the quarry etc...
As far as deco, you've already said you're using an air (21%)computer, so there is no problem with nitogen loading/off gassing computations being different than your backgas.
You've already said this is strictly a bail out/ run for home pony, but IMO I think 13 is too small. At 120' 13 cuft will not last very long. Do a search on pony size and read a few threads on this. I remember one of the threads had calculations worked out for size vs depth vs time needed to surface safely. you might be quite suprised how little time a 13 cuft will last at depth. For the extra gas I think a 20 cuft is worth the small (couple of inches length) increase in size.