Set Points Revisited

diverreb

Reading some recent posts I was wondering what set-points people are using these days. In my class we were taught a 1.2 was pretty standard for most types of diving. I'm wondering if that has changed. For the purposes of this poll consider a maximum depth range of 200 Feet (61 Meters). I assume some of you might use different set points for more extreme dives, or shallower dives... If that's the case indicate that in a post.... Also note if you bump up the set point for Deco.

Thanks,
Richie

kwinter

This is what you think about at 6:30 a.m. on a holiday? There must be a support group somewhere ...........

jkaterenchuk

I use 1.0 for the bottom portion of the dive and manually control it up to 1.3 when at 20ft. My reasoning is as follows.

1) I can verify on the surface that my Oxygen cells will operate correctly up to the ppO2. I still do a spike of the cells when descending to 20ft to confirm they reach the expected value at 20ft..
2) At 1.0 the HUD has a single led blink which is easy to read and understand. More blinks gets my attention.
3) I like the extra cushion between 1.0 and 1.6 should I have a O2 control issue that cause a spike.
4) I have found the extra deco incurred when compare to using 1.2 or 1.3 for the entire dive not a major concern.
5) Slightly lower CNS is incurred.

For me item #1 is by far the major factor as I am still very concerned about why and how several very experience divers (more than me) have died on their rebreathers. Until I know otherwise I will believe they were doing everything right and something unknown caused their accident. Diving with 1.0 setpoint takes another highly critical monitoring area which is handled by less than reliable equipment and put it more into a conservative area of my control and verification.

John

the diving tiler

.7 down to 30 meters 1.3 for down to 75 meters, 1.4 on deco station at 15 meters. Spike it on way down to 1.7 make sure all is well

cramerdn

the search function will reveal this thread as well.

http://www.rebreatherworld.com/q-and...oint-poll.html

Skipbreather

I use 1.2 since I don't often have the opportunity for multi day diving. Were I ever to actually have the time to do a long dive trip, I'd roll it back to 1.0.

hound

I keep my setpoint at .7, maintaining 1.0 on the bottom with the MK1 thumb solenoid. I guess I will pull the 1.0 lever on the poll.

I use the HUD as a primary and check the handsets at 2-4 min intervals against the HUD. The Smithers pattern seems to lend itself to maintaining a 1 or 1.1 setpoint given the convergence of the three colors around PPO2 of 1.

I also try to avoid always using 10/50, despite the ease of mixing. Combined with the lower setpoint, I can flush the loop and not have the solenoid immediately fire.

When I flush the loop I want to see an expected value and I want to see it sit there for a period of time to verify I have no creep in the O2 system.

I do a flush with O2 at 33' and note the millivolts.
I flush the loop on the bottom twice during the dive.
I temporarily increase the setpoint to 1.2 twice during the dive to check the solenoid.
I spike the PO2 as I approach the 130 or 70 stop to 1.4-1.6 and note the millivolts.

2 notations of the millivolts; 2 flushes; 2 solenoid checks.

I've adopted this setpoint playbook for no paticular reason other than it plays to my fears.

Happy 4th. -matt

Andy Del

1.3 on all dives, unless too shallow to get there. I also bump up the PO2 to 1.6 or thereabouts on deco. Simple, easy and the same each time...

cheers

Andy

lizardland

Same reason I dive on 1.0 as well. I run a pure O2 loop manually at 6m which in reality means 1.45-1.50 average at the end of a long dive.

For the difference it makes to deco (a few min) I like the lower CNS loading too.

Before I got the HH and I was diving my Mk15 with original electronics then I was running 0.8-0.9 SP. If you run it higher then I found out the hard way that if a cell connection dies then you get massive O2 spikes (I ended up on 1.7-1.8 at 65m) because of the way it averages cell readings.

Cheers,

Stuart

Dsix36

I run 1.3 unless I will be doing repetitive multi-day dives and then I drop it to 1.0
I bump it to 1.6 at 20'

__________________
THE MORE THAT I LEARN, THE MORE THAT I STILL NEED TO LEARN!!!!!!