Optima mCCR/eCCR Hybrid

Tony_Q

Given recent threads discussing the merits of mCCR or hybrid mCCR/eCCR for use in recreational i.e. less than 40m depths, I am interested in considering this modification for my Optima.

So the obvious question, have any Optima divers modified their rig to include an additional constant flow manual oxygen injection?

If so, I would be interested in whether you have found it to be a worthwhile modification, and how you have configured the oxygen addition.

Thanks,
Tony

kwinter

Ditto. I've been wondering about the feasibility of adding a leaky valve.

heyydude

Hey all,

Since the Optima has a 4th Cell Port, you could easily install a "leaky valve" into the loop at that point.

Conversely, if you were adventuresome with a drill and tap, you could install one on the opposite side of the scrubber housing.

The extant hole in the Optima is tapped for 1/4-18 NPT (National Pipe Thread) Female.

Golem Gear sells the orifices which will fit these (and other) products.

I should add that all our Hammerhead products, with the exception of the KISS Kidney have 4th Cell Ports built-in. Thus, a "leaky valve" could be installed into all of them.

Take care,

Kevin Juergensen
Juergensen Marine, Inc.

kwinter

Kevin -

If I use that port for the leaky valve, then I have to get another one tapped for the Fischer connector needed for 4th port monitoring or the new Liquivision X-Link interface. I'm not sure there is room for a 3rd tap. And tapping the other side of the lid would put it inside the water trap. I'm not sure, but that doesn't sound like a great place for the leaky valve to be.

And BTW, it might be time to update your RBW profile. The Hammerhead was added to the rebreather list a while back.:D

Ken

Tony_Q

Hi Kevin,

Thanks for the suggestion.

Smart and simple.

Regards,
Tony

heyydude

Hey Ken,

Mmmmmm.... Lets see.....

Leaky Valve
Primary with 3 sensor monitoring and trimix deco
Secondary with 3 sensor monitoring and trimix deco
Heads Up Display with Vibrating Alarm (DIVA)

And you still want to add a X1 to this?

:D

Reminds me of one of my customers who was building his own rig - he actually ordered THREE Primary Displays with Solenoids. Was going to have a unit with 9, count 'em N-I-N-E Oxygen Sensors.


I'm all for redundancy here, as well as safety - but you reach a point where you start adding "redunant wings" to the airplane - no?

:)

Kevin.

NEDIVER

Looks like I have created a monster, hopefully manufacturers will take notice and have this be an option for new units.

Now to the Optima, unlike my evolution which I have easily found a "blanking" cap for the DS4 does this blanking plug exist for the dive rite first stage?

If not you would have to run an off-board cylinder with the blanking adaptor to feed the "leaky valve". After long thought, if I were to have to drill and tap my unit, I would not continue with this quest. Fortunately, a well known manufacturer has made an adaptor that can screw directly into the exhale hose, allowing the O2 to mix in the scrubber before the sensors and give a proper reading for the solenoid to fire or not. I would be against this mod if it were on the inhale tube due to the fact that you would be getting the O2 needed to satisfy your PO2 reading then additional O2 from the leaky valve. This leads to inhaling PO2 higher than what you are reading on your handset. Is that the most advantageous? No, it is not even a question.

So what ever you decide, have the leaky valve be on the exhale side preferably. At the least have it in the head where the reading is taking place and do not even consider a mod where the additional O2 is being added after the cells and before your mouthpiece. Furthermore, if you have the leaky valve right in where the 4th cell would be, one can only assume (I know about assumptions) that the concentration of O2 right at the cells would give higher readings than actual air in the entire loop.

Even after careful consideration of having all of the mods being reversible with my evolution, and the addition of the leaky valve pre-scrubber and having the right 1st stages for the blanking plug, the conclusion that I have come up with is; Not to do the crossover. This took long debate and many conversations. Thanks to PatB for the most sensible of all the debate and that comes down to simplicity. If we keep adding and changing, pretty soon it gets hard to trouble shoot if there is a problem at depth. I have decided that that complication is not one I am willing to dance with when I have a unit that works just fine for the moment.

What is the future? Hopefully for the added benefit of all CCR's to have constant O2 flow that manufacturers will follow the lead of units like the rEVO and give the option for hCCR. This makes sense to me, if only for the benefit of increased battery life by having the solenoid fire less, it is a winner. Secondly, depth. You can plug the rEVO for depth beyond the capabilities of a blanking plug. I would have to remove the components of my hybrid transition once I am comfortable to diving those depths. Now I would be wondering which unit configuration I am diving and at which time. That starts to be too much to keep track of after 100M.

So the future for me; no conversion and a purchase of a hybrid unit that is available from a manufacturer within the next year. Right now that looks like it will be the rEVO.

Best of luck in which ever decision you make.

Dive safe,

__________________
-Tom-

"slow is smooth, and smooth is fast" TM
"Insanity is repeating the same thing over and over again, expecting different results" Albert Einstein

jradomski

when adding a leaky valve to an existing system whether it be an optima or a vision there are consderations..

Adding a leaky valve to a CCR like the HH or to a HH equipped inspiration is easy and the same reg that supplies the solenoid can be used to supply the leaky valve since the HH uses a snaptite solenoid and the pressure ranges are compatible..

If you add it to an optima you need to use an independent 1st stage.. the solenoid used in the optima is designed to work at 90-100 psi.. The vision als has a pressure limitation.. (I dont know what the performance of the new solenoid) but the original solenoids are designed to operate at 7 to 8 bar above ambient.. below this the solenoid does not reliably close and above this it may not open...

__________________
Joe Radomski
CCR Trimix Instructor Trainer
ANDI Instructor Trainer Director #10

All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.

kwinter

Thanks for the clarification Joe. I was a bit lost by Tom's post with the blanking plug. I didn't think about the IP issue with the leaky valve.

And as for Kevin's comments, as I have told you:
1. I do not have, nor will I have, deco active on the secondary.
2. I use the X1 for deco instead of the primary because I am more comfortable with VPM-B/E than gradient factors, even though I know it is still safe.

And there's also that last one minute at 10 feet business.

Ken

Tony_Q

Thanks Joe.

Would a snaptite solenoid fit in the Optima head in lieu of the standard solenoid?

If so, it could avoid the need for separate first stages (for shallower depths where a compensated first stage would be satisfactory).

Tom,
Thanks for your thoughtful comments.

Not an easy decision. Agree that manufacturer supported solution is the best way forward, but in the absence of such an option divers need to make the choice that works for them.

I like EACs so rEvo not an option for me. APOC looks like it will take more time to get sorted than initial hype would suggest (it was my Plan A for next year APOC +HH, now only Plan B) , so modifying the Optima looks the only practical option in the next 12-18 months.

If DiveRite were to offer a solution, I would obviously just take that up, but unlikely short-term.

Also, it is a lot harder for my wife to see the dollars spent on converting the Optima to hybrid, than if I purchased a separate mCCR. There are only so many places in the garage/bedroom/garden shed to stuff gear out of sight:)

Planned dive mode would be as manual mode with eCCR parachute, similar to how a number of divers now dive their Optimas (but without the leaky valve installed). Hopefully minimising some of the risk in PO2 monitoring on expired rather than inspired PO2.

I think the good monitoring habits engendered by diving in mCCR mode will help fight the complacency which can creep in when the eCCR just keeps working (till the day it stops working).

Regards,
Tony