ECCR Upgrade, .... Feedback Wanted

Scuba_Vixen

Hi Guys,

Following on from the thread on finding a smaller (.0030") orifice for my KISS valve, the idea of just putting the plug (available from Jetsam) in it and adding a solenoid valve, controlled from my HUD controller and making it eCCR has me thinking seriously.

The KISS valve would remain in a "manual add only" mode.

Seems the best choice of reasonably available solenoid valves is the Snap-Tite Wattmiser series, with the 0.025" orifice being the smallest they have.

This would translate to about a 1 to 1.5 second pulse, once per minute with a depth compensated 1st stage and a ~7bar IP.

From reading several related posts, it seems the solenoids in most CCRs draw in the 300ma range, so that should indicate that the 1.5Watt coil option for the snap-tite is the better choice. (assuming a 6V coil)

My thinking is that running the solenoid valve in a parallel configuration with the KISS valve with a flow stop in the solenoid valve's supply line would be the most reasonable way to go. .... any issues with the solenoid valve, and it's O2 supply can be cut off, still leaving me manual control to abort and surface.

With the current generation of my HUD controller, I have room in the electronics canister for the solenoid driver circuit and more than ample battery capacity. Carefull use of a Dremel tool will gain me access to the pair of needed I/O pins on the microcontroller. Coding for solenoid control shouldn't present much problem, although any form of "voting logic" isn't within it's cabability.

Anyway, for those still with me here;

1) I could use some feedback on how often your solenoid fires, and for how long, while at a more or less constant depth.

(I know it isn't always the same, I'm just looking for the general ranges)

2) If you have experience with the Snap-tite valves, what orifice, IP, and coil worked for you?

#) Anything else relevant you want to share is welcomed.


Thanks in advance,


Darlene

RonMicjan

are you thinking about just having it fire on a timer, or give you a button to fire it electrically? Is this just to be able to dive deeper?

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decoweenie

Darlene,

As you are aware, the solenoid firing frequency depends on the O2 metabolic rate of the diver at the time. And the amount of gas injection per fire cycle.

Example of 2 different methods from 2 systems: the original MK15-X fires a fixed duration per cycle since it has a O2 reservoir, and the YBOD fires a variable duration per cycle depending on the offset of the loop PO2 to the set-point.

Combining both of these will affect the frequency of solenoid firing.

So keep those in mind when you are evaluating responses from different people. What system are they using ? What is the work rate of the reply ? Etc.

Lastly, your metabolic rate from the other thread seems to be quite low as well. So also don't forget to factor that into your final timing.

My timing...

On the YBOD at constant depth and a steady swim with stage(2) and not strong current, the solenoid fires approximate every 10 seconds (or less) for a short burst (i.e. 2-sec) on the average.

Again, this is only an approximation and never timed exactly.

I have a relatively higher O2 metabolic rate than you with my KISS IP set ~12bar+ using 0.0035" orifice, and I only have to add every 10-15 mins on deco to keep set-point. And I think probably from off-gassing.

Scuba_Vixen

Bird Precision has suitable orifice replacements in the smaller size, and I'll likely get one, but I like to make things for myself, and functional electronic PO2 control shouldn't be too big a deal. I'm not that far away already.

It's really much more a goal to accomplish, than something to dive it deeper. The real advantage, either way, (eccr or smaller orifice) is that it won't waste gas from a creeping PO2 and required dill addition to get it back down.

The way my HUD controller is set up, it sequentially reads the A/D result of each of the 3 cells. Depending on what that is in relation to the programmed set point, it then lights the prescribed led(s) in the hud display so I know where my PO2 is at, relative to where I want it to be. It also blinks non PO2 related leds in the HUD, 1 , 2 or 3 times to tell me which cell is being displayed.

It holds the display of each cell for about 2 to 2.5 seconds, then goes to the next. It takes about 6 to 8 seconds to cycle thru all 3.

The way the code handles the A/D result to give the proper led display, also lends itself to firing a solenoid for a short duration, if needed, while each cell is displayed, programmed solenoid duration gets keyed to the amount of deviation from setpoint.

As long as there is minimal deviation, the solenoid doesn't fire. The more deviation, the longer the duration. It's basically proportional control. I expect durations to be between ~.4 seconds and 1 seconds, maybe 2 or 3 times per minute to stay very close to setpoint.

Actual experimentation will tell.

Unfortunately, the Basic Stamp microcontrollers aren't the best choice for controlling a HUD and a solenoid, as they aren't multitasking, but this implimentation should work acceptably. ... It just has some limitations, and it's not fancy.

I'll likely code it, so that it doesn't initiate untill you reach a 1.2 PO2 for the first time from manual addition. Resetting or turning off the controller post dive, will turn off the solenoid control. (or at least that's the plan at the moment)


Darlene

Scuba_Vixen

Thanks so much for the info.

As you can see from the post above, I have the option of programming the solenoid control to check the deviation from setpoint everytime each cell displays. The control would only fire if there was enough deviation to warrant O2 addition, and for a duration proprtional to the deviation.

It looks like AP has specific solenoid valves just for them. Those timing numbers would indicate a much smaller orifice than the snap tite. The number of times it fires though, is a good indication of how little power it consumes, so that battery life is acceptable.


Thanks again,

Darlene

I'd really like to hear from the Meg owners

Maybe Joe R will catch this thread and purloin me a Meg solenoid valve to work with.

caveseeker7

Darlene, the PRISM injects 1 sec in a 5 sec cycle. As needed, of curse.

If memory serves me right, the HH variable injection times, up to 3 sec in a 6 sec cycle.
Should be in the manual, and Joe the cycle posted somewhere.

I like the idea of a solenoid supply shut off valve.

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Cheers
Stefan



"Political Correctness is a doctrine, fostered by a delusional, illogical minority,
and rabidly promoted by an unscrupulous mainstream media,
which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.!"

dan@scuba-training.net

Battery life and power consumption on the Inspiration, Evolution, Megladon and KISS (the only systems I have experience with) is adequate, but...

1. All ECCR's need batteries

2. All ECCR's need trim weights

What if an ECCR had a battery that was big (and well placed) enough to serve as a trim weight?

The Designer could use a solenoid that had much greater power (and power consumption) than the current ECCR's use.

(I'm talking about a solenoid like the one that operates the door locks on my car, or the one on the starter...)

(Ok, maybe not that powerful...)

The more powerful solenoid could easly over come the intermediate pressure of a standard scuba regulator for the oxygen injection. There would be no need to adjust the first stage to supply lower than normal pressure.

Just a thought, worth exactly what you just paid for it: Nothing!

decoweenie

Very interesting out of the box thinking there!

However, people might object to having to lug heavy batteries on trip. And batteries on planes are touchy subject as well. And "heavy" batteries are not as common.

Unless you were thinking about a LOT of D-cells...

caveseeker7

Double D cells probably.
So easy to get distracted from a good thought ...

__________________
Cheers
Stefan



"Political Correctness is a doctrine, fostered by a delusional, illogical minority,
and rabidly promoted by an unscrupulous mainstream media,
which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.!"

RonMicjan

I dont think so Tim... (err, Dan)

what runs your power door locks is an actuator, an electric motor with a gear and rack that is wired to be reversing polarity

there is no need to adjust the pressure down with eCCR now, the crop of solenoids the various CCR manufacturers use work just fine. Darlene's VO2max is low so she needs to turn down the IP with a KISS valve attached, so her PO2 wont creep up at low work rates. We are all working making CCR's lighter and more efficient, not heavier. Bigger solenoid, larger heavier batteries, means more weight, and more cost, kinda backwards dont ya think?

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