Rebreather World - View Single Post - PO2 Set-points (WHEN!)

Drmike · 20th April 2008, 11:57

Quote: (Originally Posted by silent running)

Yes Mike, proper venting happens easily with a nice, loose OPV, aided by pushing down on the CLs with one's hands and the occasional nose vent.

I never let the CL fill so much on ascent that the opv has to open - no need, and no need to crush lungs manually. On ascent I simply shut the adv off and nose vent to keep min loop and that also helps keep setpoint too at same time (high) People not maintaining min loop and letting OPVs control lung vol an ascent is probably one reason you seldom see ECCR divers with horizontal trim during ascents

I suspect if people find they cant keep up with expanding CL volume on ascent by nose/mouth venting they are probably ascending too fast.

If mouth venting you only break lip seal when you sense a pressure differential. No water should enter the dsv then provided you maintain depth or are ascending. Unlike nose venting, the trouble with mouth venting is you cant maintain min loop vol this may effect trim adversley during ascents

Quote:

My AP buddies all complain about the super tight stock OPVs and how they only activate by pulling on the dump cord, a design feature which may help facilitate pressure tests on the surface, but which certainly isn't convenient in the water, either during a slow ascent or even potentially injurious during a fast, emergency ascent. And why is the OPV nearer to the bottom of the CL? A great feature, if you dive upside down and like pulling on a string.

why dont they lower the opv opening pressure when diving by unscrewing it? (thats how its designed to be dived and how I dived my inspiration) Locking it down is done for over pressure testing only.

Quote:

If one were to use a rich dil targeted to the max depth, overshoot will be even less, even if you pause during descent, which is another argument for richer dils...

Dont you mean the other way around?. Rich dils aid overshoot

What do people think will happen if they spike their ppo2 to say 2bar on descent for a few seconds before further descent causes the adv to fire in dil that will lower it? - sweet FA I should think

personallly I always spike my ppo2 momentarily well over setpoint on descent as I want to test for current limitation before the dive not after

20th April 2008, 11:57	#13 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,128	Re: PO2 Set-points (WHEN!) Quote: (Originally Posted by silent running) Yes Mike, proper venting happens easily with a nice, loose OPV, aided by pushing down on the CLs with one's hands and the occasional nose vent. I never let the CL fill so much on ascent that the opv has to open - no need, and no need to crush lungs manually. On ascent I simply shut the adv off and nose vent to keep min loop and that also helps keep setpoint too at same time (high) People not maintaining min loop and letting OPVs control lung vol an ascent is probably one reason you seldom see ECCR divers with horizontal trim during ascents I suspect if people find they cant keep up with expanding CL volume on ascent by nose/mouth venting they are probably ascending too fast. If mouth venting you only break lip seal when you sense a pressure differential. No water should enter the dsv then provided you maintain depth or are ascending. Unlike nose venting, the trouble with mouth venting is you cant maintain min loop vol this may effect trim adversley during ascents Quote: My AP buddies all complain about the super tight stock OPVs and how they only activate by pulling on the dump cord, a design feature which may help facilitate pressure tests on the surface, but which certainly isn't convenient in the water, either during a slow ascent or even potentially injurious during a fast, emergency ascent. And why is the OPV nearer to the bottom of the CL? A great feature, if you dive upside down and like pulling on a string. why dont they lower the opv opening pressure when diving by unscrewing it? (thats how its designed to be dived and how I dived my inspiration) Locking it down is done for over pressure testing only. Quote: If one were to use a rich dil targeted to the max depth, overshoot will be even less, even if you pause during descent, which is another argument for richer dils... Dont you mean the other way around?. Rich dils aid overshoot What do people think will happen if they spike their ppo2 to say 2bar on descent for a few seconds before further descent causes the adv to fire in dil that will lower it? - sweet FA I should think personallly I always spike my ppo2 momentarily well over setpoint on descent as I want to test for current limitation before the dive not after __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you Last edited by Drmike : 20th April 2008 at 12:14.
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