Pictures of OSTC and PO2 card diving

[andersnasman]

I attached some pictures from a testdive with the OSTC this weekend. The OSTC is connected to an Inspiration classic.

Dive data:

Water temp 1.3C
Max depth 40m
Dive time around 35 minutes
OSTC software version 1.23

PO2 electronics installed in a box together with the six HUD LEDs (which I should move out of the box shortly). The PO2 card was only powered from the OSTC. The three pull-up resistors on the PO2 board for the sensors was taken away.

The connection to the Inspiration was made by parallelling the sensors. I mounted the cable through a Beanie adapter (http://narkedat90.com/shop/product/clas ... ll_holder/) so I didn't have to drill holes in the Inspo.

Almost all went fine. I had one problem which related to that I connected the card to the OSTC after I started the OSTC, this caused the OSTC to start emulating a dive (to 70m). When I got passed that problem all went fine and it all behaved as it was supposed to.

I will publish some close-up pictures of the installation on both Inspiration and KISS with DS-1 shortly.

[Anonymous User]

Well done!

Was the OSTC O2 card inside the Inspo head?

One comment on paralleling the O2 cells. My personal opinion is that it is a very bad idea on any rebreather as this reduces reliability and can actually interfere with the critical life-support pPo2 control of the rebreather. This critical life-support on all rebreathers I know have not been formally tested other than in accordance to in-house manufacturer protocols. This means that the "life-support" element of the electronics bear no CE EN61508 formal verification. Adding experimental stuff like the OSTC board (i.e. paralleling the O2 cells) to non EN61508 electronics (built only to manufacturer's or sub-contractor internal inhouse standards) compounds potential problems and risks.

I am working on an alternative system which employs 3 inpendent O2 cells mounted in the counterlung and which is due for manned testing first week of February. The advantage is that you would have truly independent thrid party monitoring of the inhaled gas. Details of the project are here: http://www.rebreathermallorca.com/forum ... icseen#new . If manned testing succeeds I will prepare a full report, and it would be nice to connect the OSTC to the contraption under test.

[andersnasman]

The PO2 card is in a separate water tight box (in which I mounted the HUD LEDs now for testing). The test rig is the one seen in the pictures, stashed under the OSTC.

The same setup could be used with three separate sensors as there is room for more sensors in the Beanie adapter (see link above for). That way You wouldn't interfer with the master cells. By the way, the cells in the Inspo are already splitted between the two computers (as in most eCCRs). The most important thing is to at least meet the 10kOhm stated by Analytic devices? For testing purposes using the master cells is fine for me.

I would not put the cells in the lungs as that's the place that collects most moist. I would consider the the middle upper part of the cannister to be the safest place to put cells and electronics (at least for Inspo and KISS).

Well, at least that's how I see it.

[heinrichsweikamp]

Here is a nice approach for dry sensors:

http://www.theadaptivesystem.com/electronics.html

regards,
Matthias

[Anonymous User]

I like Camelion!

As to O2 cell location, the only place to retrofit on most if not all rebreathers 3 additional O2 cells is in the top section of the inhale counterlung.

This section is generally immediately after the O2 cells in the can and high up. The O2 cells need to be protected with a cage from direct contact with the counterlungs.

[andersnasman]

Attached is a picture of a Beanie style adapter for an Inspiration. In the red circle You can see one of the empty holes for extra cells in the adapter.

[andersnasman]

Some more pictures of the test installation.

[Anonymous User]

Cool!

Is the pO2 casing 1 ATA sealed?

[andersnasman]

Yes it is (1ATA), and the cable is solid. Im thinking about filling the box with oil when I do the final version). I'm not very fond of exposing another opening into the Inspo (there are far too many already).

I have had thoughts about mounting the electronics inside the Inspo loop, but I don't like having active electronics inside the breathing loop (comments?). This way I would have to have two cables coming out of the Inspo, one for HUD and one for OSTC.

[Anonymous User]

The only consideration I feel strongly about is the piggy-backing and sharing of the Inspo O2 cells with the OSTC electronics. I do not think this setup gives any significant reduction of risk, and may actually contribute to a serious accident.

The box for the OSTC board... two thoughts:

1. Larger aluminum box for the OSTC to house both O2 board and OSTC electronics (the OSTC though is quite nice and compact and it may be better just an aluminum housing for the OSTC electronics alone).

2. Standard aluminum box to be produced in mass for cost reduction and be sold together with the board (by mass I mean designed and produced together with the board and sold as a package).

[christian]

I agree with not placing electronics into the loop,

i was running the diamond hud ( rebreathersolutions) for two years and now it completely died as the circuit board corroded far too much ( possibly have to put this into "experience")

On another note - splitting the feed to the inspo's o2 sensors has always worked very well for me.
The only problem is were to get the molex connectors as no-one has them over here.

Were did you buy yours from ? As i need some as well.

Cheers
christian
New Zealand

[sailor]

christian Wrote:
----------------------------------------------------
> The only problem is were to get the molex
> connectors as no-one has them over here.
>
> Were did you buy yours from ? As i need some as
> well.
>
> Cheers
> christian
> New Zealand

Hi,
you can find Molex connectors here:

www.tecme.de

and here:

www.dtuag.eu