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24-07-2020, 07:44 AM
To clarify the state of the cells in my machine.
All of them work, reading low and high. All of them show 1.6 at 6m following an oxygen flush.
One cell, which I'll call Paulo, is a bit slower than the rest and this has been moved off of the controller and on to the backup. It eventually reads OK but has a slightly lower mV reading and seems to need to warm up. This sensor will be the first to be replaced once cells are available.
All others are well within tolerance and read the same.
24-07-2020, 08:07 AM
The big difference between a Revo and Inspo (as far as I'm aware - don't have any experience of Inspos, etc.) is that the Revo evolved from a manual CCR.
Originally Posted by gobfish1
There's an orifice which constantly injects O2 into the machine at your resting metabolic rate. This means that the oxygen injection solenoid will need to fire much less often than a full electronic CCR, maybe several minutes between oxygen squirts if you're 'at rest'.
The Revo training encourages running the machine manually by setting the controller's setpoint slightly lower (e.g. 1.2) and running the machine manually at the nominal setpoint (e.g. 1.3). This was referred to as "parachute mode"; I've heard lots of Revo divers mention that they regard the sound of the injector as being a slight slap or reminder that they've failed to fully monitor their PPO2 levels.
Should the solenoid fail open -- should be a rare failure mode -- then the O2 needs turning off (and if MOD1, bailout and terminate the dive) and possibly be controlled by feathering the valve (a MOD? technique??). TBH I don't know the 'advanced' answer, but would guess you'd plumb in your high % bailout gas into the injection block and inject manually. I do know that for deep dives, two oxygen cylinders are used -- need a Revo MOD3 person to clarify.
Should the solenoid fail closed, no problems, just carry on as if it's a manual machine. In fact if you're running it in parachute mode, you should never use the solenoid in a dive.
The setup checklists (there's 4 checklists which are followed: build, close, predive, prejump) checks the solenoid several times and measures the solenoid battery voltage post-3x injection.
Small point about batteries on the unit; there's 3. One in the Petrel controller which does not drive the solenoid. A separate battery to drive the solenoid. A battery in the Nerd backup. A failure of any one doesn't affect the other systems (OK, if the Petrel fails then there's no auto solenoid operation - you still have the Nerd with two cells, or bailout).
24-07-2020, 08:19 AM
So you’ve already moved the cell? If the slow reaction follows the cell it’s the cell if it stays put it’s more likely connector / wiring or another cell with duplicate issues. How old is the cell ? Worth looking at the cell connection to check for contamination. Be wary of that cell and in an inspo I would be looking to change it out , if it’s too slow it would throw me cell errors.
24-07-2020, 08:28 AM
Wiring/connection issues won't give you slow responses, only voltmeters at the end of the day
Originally Posted by Vanny
Sluggish cells probably some weirdness with the membranes or the chemistry of them.
I've had one do that from being silly and laying my unit down on it's back leaving a puddle of condensate on the face of cell 2, it did recover but was always slow afterwards.
To be honest it wouldn't bother me if my cells reacted at different speeds, you soon get used to how they behave and any "oh shit this is weird" just dil flush and you've got a few minutes thinking time there.
24-07-2020, 09:02 AM
The difference is you have years of experience. Someone with 8 hours of Mod1 training and no experience thinks that he is equipped to make the same judgement calls
Originally Posted by WFO
24-07-2020, 09:11 AM
I was taught feathering on my MOD 1. MP had me do it every dive as part of the skills refresher as the course progressed.
Originally Posted by Chrisch
24-07-2020, 09:20 AM
No nothing of revos, only used inspos - does that mean there is only one battery powering the solenoid so what would happen if this crapped out on you? Will it still run mccr as normal just requiring you to keep a closer eye on the ppo2?
Originally Posted by Wibs
24-07-2020, 09:24 AM
I had a sluggish cell, but only when under pressure and even then not consistently. On the surface it was fine. I moved it around the unit, both by swapping connections and physically moving the position and it remained sluggish. I swapped it out. I didnít have the experience to know what I could manage and frankly, the headspace it was occupying wasnít worth the 60 quid a new cell costs.
None of my cells, a mix of AP and Narked lasted past the warranty date anyway. I had three AP13 in the unit when I bought it, all narrowly in date and I replaced the sluggish one with a Narked and bought a spare at the same time. The Narked failed so was returned and replaced and the spare was fitted. As they were out of cells at that point I also bought 2 AP14 which were fitted as the 13s went out of date. None of them made it as far as the 13s, but thatís what warranty is for.
Originally Posted by Chrisch
24-07-2020, 10:08 AM
A fair point. Other thing to consider is I am on MCCR and only looking at 3 cells. Keeping track of 5 of them would confuse the bollocks off me
Originally Posted by Paulo
24-07-2020, 10:19 AM
Thanks for the reply.
Originally Posted by Wibs
I understand how your unit works just wanted to know how you came to the conclusion that you had a superior unit over a nother .
A diver can run his AP/eccr rebreather with his set point at 1.2 or 1.3 and then keep his set point at 1.4 requiring less interaction from solenoid.
Solenoid no much use as you descend limited use at your fixed depth and only gets a work out on accent
In fact I could do a 3h dive and not have it kick in. ( But liked to give it a bit of a work out just to stop it rusting up lol )
Also the ap unit has two controllers and two batteries plus on my old unit Iv a SW plumed in that also has its own power. Also the ap units have the option to add more cell if a diver was so inclined.
Ps you mention a 2nd O2 cylinder on other mod course that will be for when the leaking valve stops flowing due to ambient pressure .
I'd take the plum out your mouth and get some dive time in . The come back and give us all a up date .
Ps the last dead CCR diver I seen wasn't to arsed about a clean chest and good trim . Just something to think about . ( I think back Mount lungs are a compromise and was happy to suffer the extra clutter for a better all round performance) just my preference.
Enjoy your new unit and get some dive time in .
Last edited by gobfish1; 24-07-2020 at 11:25 AM.