Were you taught this math in your entry level CCR class?

[rjack321]

@broncobowsher why bother burping it down vs. just breathing it down if it doesn't exceed 1.5/1.6? It'll come down on its own in a few minutes

Hit the bottom, working hard cause its not slack like it's supposed to be, looking for the wreck... yea I am dil adding and/or flushing first THEN running a line and looking around because the next few minutes are going to be distracted and I dont want to look up in 3mins and see 1.8

 

[tbone1004]

@rjack321 I'll certainly give you that one.

Do you use a dil mix that gives you a reasonable ppO2 on those dives at the bottom, or would you use a leaner dil for that? I.e. 100ft dive using air instead of EAN32 for dil so the ppO2 comes down a bit faster on descent?

 

[broncobowsher]

@broncobowsher why bother burping it down vs. just breathing it down if it doesn't exceed 1.5/1.6? It'll come down on its own in a few minutes

The idea is that it will drop as I descend, leaning it out with Dil. The CMF on the Revo is dialed in fairly well for me, so just breathing it down can take a long time. Longer then I want to spend that high. I'm already above the targeted highest PPO2 and want to drop it a little. The burping the loop is only if I am not getting the PPO2 down to a reasonable level in a reasonable time.

 

[tbone1004]

@broncobowsher if you're on a CMF that makes a lot more sense.
One of the perks of the eCCR's is that it definitely leans out for descents quite a bit better. I'm thinking that if I was in that situation I'd probably run my dil mix a bit leaner than I do on the eCCR's so it can drop the ppO2 a bit faster. I dive a dil with a ppO2 higher than my normal setpoint on a pretty frequent basis *EAN32 in cave country*, so in a cave like Jackson Blue, Little River, etc. where there is a pretty rapid descent or if in the ocean going straight to 100ft ish it will regularly hang out around 1.5 when I hit the bottom vs. a high setpoint of 1.1 but it will come down in less than 10 minutes vs. a CMF where it may never come all the way down.

 

[JohnnyC]

Needle valve for the win! Stuff it closed for the descent, open it up on the bottom, whack it open to deco out.

 

[rjack321]

@rjack321 I'll certainly give you that one.

Do you use a dil mix that gives you a reasonable ppO2 on those dives at the bottom, or would you use a leaner dil for that? I.e. 100ft dive using air instead of EAN32 for dil so the ppO2 comes down a bit faster on descent?

16/50 is my normal all purpose wreck diving dil. This is one reason why offboarding dil in the ocean doesn't make much sense to me. I can bring 3 or 4 CCR bottles of trimix dil and a couple of different BOs that I can select based on the actual profile.
So for this past weekend I brought a bunch of trimix CCR bottles. A BO of 32%, a BO of 21/35 and a BO of EAN50. I ended up doing a 165ft, 110ft, 100ft, 70ft, 85ft, and 95ft dives. I appreciated the trimix poking around inside wrecks at the 90ft depth too, even if I had 32% BO