My O2ptima Configuration

n2diving

> Do you have a second stage attached to the Diluent tank?
Yes, the RiteSource is a BC integrated second stage. Switching to it is incredibly fast, in part because recovery of the second stage is something that will be practiced multiple times on every dive. I'm aware of many O2ptima divers who have both an outboard bailout and a RiteSource. The emergency strategy is the extremely fast switch to the RiteSource for the sanity breaths and then either return to the loop or switch to offboard bailout. However, some experts consider the RiteSource an additional risk on deeper technical dives.

>do you consider the adv suitable for bailout?
No, the O2ptima ADV is not suitable for OC bailout.

>Are you going to just use the plastic plug for the scrubber or do you plan to eventually make a delrin insert?
No, the factory installed cartridge plug is already in place, is a hassle to remove, and I fail to see any advantage to replacing it with one made of delrin. If you are ultra paranoid about it, keep the plug from the previous cartridge and put one in both ends.

> Have you considered diving without a full cover?
No, although the prototypes did not have covers. I like the cover, it streamlines the unit and reduces posibility of line traps. It's extremely light weight and I do not to see any benefit to removing it. I'm not aware of anyone who is diving their O2ptima without a cover, but if you don't want it I see no objection to removing it.

> Would it be easier to add a hose with (Kiss style gas addition) with a laser cut orifice and a ball valve?
No, and I'm not aware of any O2ptimas that have been modified this way. I don't see any benefit to adding a constant flow valve other than to reduce the number of manual O2 additions, which are not at all burdensome for me or my sister. My sister has a camera in her hands most of the time and she says managing her PO2 manually is no trouble. If you are asking why we don't dive an mCCR instead of an eCCR, that's a discussion for another forum.

Crazyduck

Thank you...
Regards Andrew

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Presently in a state of transition from Open Circuit to Closed Circuit.

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MarcLaukien

What is this risk which some experts believe it has on deeper tech dives? Freeflow? Wouldn't this be a risk regardless of depth?

Sorry for this basic question, but what is an ADV, and how does it relate to OC bailout?

sensor330

[quote=n2diving;96308]
Primary Monitoring: It's unclear to me how not monitoring the primary handset in our configuration could lead to a situation where we did not know our PO2. The typical configuration does require the diver to compare the primary display to the secondary HUD. However, we are monitoring PO2's via four sensors, three via the HUD of the secondary and one completely independent sensor via the VR3, none of which are dependent on operation of the primary. I suppose the primary could fail in two ways: one such that it fires the solenoid and causes a high PO2 or the other such that it does not fire the solenoid and causes a low PO2. In our case, failure of the primary such that a low PO2 is caused is unlikely since we don't rely upon the primary to maintain PO2 and such a failure would go unnoticed. A high PO2 would be noticed by our monitoring the four sensors from two other independent sources as well as the sound of the solenoid firing, which would be abnormal.


quote]

On my primary I've seen one out of the three cells voted out while on the secondary the cells were within spec. When I'm diving and I see that one cell has been voted out, the dive is over. Although it is not a emergency it is something that definitely requires attention, especially if you are doing cave, wreck, or deep diving.

While I haven't yet connected my 4th cell I can not comment on how well it tracks PO2. I have everything to connect it but I have the following concerns:

1. Another calibration to do;
2. two more failure points;
3. another cable to deal with;
4. added complexity; and
5. added maintenance cost.

If anybody can give me some good feed back as to why the 4th cell would be a good addition it would be much appreciated.

Scott

n2diving

I'm not sure how the oxygen sensors are wired to the handsets in your rebreather, but on the O2ptima, the only circumstance that I'm aware of which could cause such a occurance would be slight calibration differences between the two handsets, which is almost unavoidable. There could be enough variance between the two that one might be voted out on one handset and not on the other. In fact, I would suspect the only time that both handsets would vote out a sensor at exactly the same moment would be when a sensor underwent a sudden and significant change. Normally the secondary handset will indicate a 0.5 or 1 millivolt lower reading on the sensors anyway due (I'm told) to the difference in cable lengths. The behavior would be more likely if the two handsets were not calibrated within a minute or two of each other.
I would not assume a minor calibration variation would be a reason to abort a dive.

Sensor variance is another matter, although again not cause for immediate concern. On my longer dives a sensor variance is common. At some point in a two or three hour dive I would expect to observe a range of 0.1 or 0.2 ATA between the highest and lowest. A wide variance on one of the sensors against the other three would suggest that it be more closely monitored, but would not suggest I immediately abort the dive. Most of these effects are moisture related and transitory, often responding to a dil flush. Monitoring the actual readings of all four would still not seem to require routine monitoring of the primary display, but if I saw a wide variance I always have the option of checking the primary.

The debate of the benefits of a 4th cell seem to be more an issue of personal preference and tolerance for risk vs complexity. Since I sell O2ptima's I've talked to a lot of people about their configuration requirements and have observed that some people feel it's an absolute requirement and others feel it's completely unnecessary. I've heard and read the arguments on both sides. I can only add that it's a popular option and that both my sister and I like having an independently monitored 4th cell.

n2diving

The problem is more generally considered 'dribbling' that goes unnoticed, but also of course freeflow. While it is always a concern, the impact of dribbling or freeflow on the diluent is greatly magnified at depth and could cause rapid depletion of diluent. Also, part of the concern is rooted in the fact that the ScubaPro AirII, the most popular version of the BC integrated octo, has something of a history of intractable dribbling. Although the Dive Rite RiteSource does not seem to have the same problem, at great depth most would not consider bailout to dil a viable option and therefore having the RiteSource in the configuration is a needless risk.

I agree and consider the RiteSource risks outweigh it's benefits on very deep diving. However, our configuration as presented is for recreational sport diving and I believe it to offer signficant benefits. I've observed a signficant and consistent difference in execution speed between a traditional off board bailout and RiteSource bailout on enough different divers, some very highly skilled, that I think it merits consideration for recreational sport rebreather configurations.

JPJones

8/60 works great and I would disagree with removing the rod I tried it and can cause a false high PO2 reading.

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n2diving

You are correct about removing the rod. The reason Lisa and I can get away with it is we don't rely upon the solenoid injection, we use manual.

However, the new FX rod is a big improvement and I may go back to using it, because it's so painless compared to the previous designs.

-- Mark

JPJones

I still like my original prototype best but it was not dummy proof enough. I fly auto unless I'm shallow and need the fine control.

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wsparks

New FX Rod? What changed? Is this something new for me to "upgrade to"???