Read and Learn......

silent running

Very well put Pete. Know what you're breathing, you're not at the surface so you can't take for granted what the O2 content is until you look at your PO2 monitor...

webhead

I can confirm that on the Apec 1 and the ISC/Shearwater heads, there are power switches on the head that end up inside the canister body when assembled for diving. The A1 has a timeout that turns off the display (still fires the solenoid) and the ISC/SW can be turned off from the handset in software (display and solenoid off). Both will turn on in the water - A1 has pressure sensor (actually displays depth and dive time) and the ISC/SW has a wet switch.

So if you do a proper pre-breath, unless you open the unit or the batteries die, the unit will self activate when you start the dive.

__________________
"These are not the droids you are looking for.... move along" - Obi-Wan Kenobi

decoweenie

... but how is the quality of life as a cynic going thru life afraid of everything ?

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"...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..."

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UKSteve

Thanks for the info...

It would seem that the Inspiration and Evolution then are in the minority of production eCCRs (don't know about the Prism) in that if you jump in with handsets off they will not come back on again due to a pressure / water switch.

Given that there must be power running to the handsets to allow the "soft" switches to work I wonder why APD went down and have subsequently stayed on this path?

I personally would prefer to see the handset switching on automatically... and other than maybe it burning through batteries faster is there any other reason why they might not have provided this function?

Steve

PhilSiswick

Is there a risk that you could end up with a situation where an uncalibrated unit switched on automatically and does more harm than good. You wouldn't know that the calibration wasn't correct. If the unit isn't switched on, you should bailout - the safe option. Also, how would you deal with the self-test routine? Would you skip that if you leapt into the water with the handsets switched off - not a good idea, I'd say, but would a self-test be valid underwater?

You could put a time-out in, that the unit only auto-switches on if the period between self-test and/or calibration was up to x hours before, but that still leaves you with a strong chance that you could hit the water and the unit wouldn't switch on.

I'd love to know why AP have not gone down this route, but I suspect that there is a pretty good reason.

Cheers,

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Phil (WSKD 0001)

I have always felt that the dive I am on is not nearly important as the dives I plan to be on the rest of my life. Tom Rose, 2007

The person who gets the farthest is generally the one who is willing to do and dare. The sure thing boat never gets far from shore. Charles A. Lindbergh

www.hugsac.org.uk

silent running

Hello Steve, FWIW, the Prism has a hard on off switch, which can and is used underwater by most of us when we fly manual. But the passive/analogue 2dry will show PO2 at all times as it's powered directly off the cells, nothing to turn on there. So jumping in without powering up is not a problem as long as you check your 2dry and switching on the unit underwater takes less than a second and the solenoid fires twice on powering up. The switch is a big magnetic reed switch that's usually mounted on the BC inflater, easy to find.

IMHO, if the unit is not able to be turned on and injecting within a second while underwater, it should definitely have a wet switch. If you jump in without powering up, you shouldn't have to scroll through a bunch of screens to get your PO2 and start the unit injecting... -Andy

jptaylor9

Could it be liability? Act of turning on unit, you accept responsibility?

The manual has 3 very clear statements, highlighted with an exclamation icon:

1) If not turned on, no oxygen control, can lead to ... and death.

2) There are no wet contacts, DIVER has to take responsibility for turning on electronics AND opening both O2 & Dil cylinders

3) It's the divers responsibility to ensure all systems are functioning prior to and during the dive.

JT

jptaylor9

If VISION is turned on & before it goes into dive mode, it will maintain a set point of 0.21 with a low oxygen warning at 0.16. But you still have to turn unit on.

UKSteve

Pete S & Admin / Moderators...

I am very conscious that this thread might be considered by some to be going off topic due to my wittering... though it might also be considered to be going to the core of the tragic loss of Nigel.

.. if you consider it proper, could you perhaps strip out the auto switch-on discussions into a separate thread?

Regards

Steve

UKSteve

What I think would be preferable is that the unit powered up and flashed every bell, whistle, alarm and HUD at you and said BAIL OUT & SURFACE!!! on the hand set(s) ...while perhaps trying to maintain a ppO2 of at least say 0.5 bar

This would be well within the error range of even quite old cells (to avoid O2 hit). At shallow depths it might also start providing positive bouyancy.

Steve