Prism Topaz - Analog Secondary & Cell Sensors

caveseeker7

I'm afraid I'm gonna make the world all bad again ... can't be helped.
Then why don't you try the other way round for a change?
Think first, then ask questions. May actually answer the question before you ask it.
Especially when the answer is obvious. Not many people here enjoy arguing for arguments sake.
Not many people try hard to engage in absolutely pointless discussions.

And it never occured to you there's a reason for that?
Never occured occured to you that there's a reason that is mentioned repeatedly
in the manual?
That it is a manufacturer's recommendation?

What understanding? All I see is either lack of understanding, pigheadedness or trolling.

You got one part right, the mechanism is better protected, not protected.
Even on a sensor setting the gauge can be damaged, though chances are considerably reduced.
The reason for leaving it in position #2 was given in the second post of this thread.

As long as the dial stays in that position, yes. But dials can be inadvertedly moved, between positions the current will be cut, in position S and B there will only be a current if the unit is powered up.

There is no need to "age" the sensors evenly. Has been pointed out before in this thread, too.

Judging by your wrongful conclusion not much of an achievement. Chett didn't make the suggestion to do this, he asked if it was best to leave the gauge reading a sensor if stored safely. So far you seem to be the only one who has achieved the infinite wisdom to consider that a great idea.

Maybe set aside your own greater knowledge for a moment and consider that many PRISM divers/owners/instructors/ex-employees/manufacturer have more knowledge coming from their experiences.

You trained with Matt, haven't you?
Ask him how many damaged secondaries he has experienced, and how long in his experience it takes to get it fixed.
You know Robert, ask him how many damaged secondaries he's come across.
These are good people, Warren, learn from their experiences.

No, really, there isn't. On the other hand you gave a good reason not to in your 2nd sentence there.

Sensor aging has been covered.
Financial and supply consideration have been covered.
Bad experiences have been covered.
It's an essential part of a live support system, don't gamble with it.

Besides, I've been hurled out of bed by a quake once, safe storage in CA seems to be a very relative term.

Well, obviously I do, and I'm rather sure I'm not the only one.
The previous replies oughta be an indication. If there aren't any more in support of post #2,
it probably has little to do with disagreement and a lot with useless debate.

__________________
Cheers
Stefan


Be Water, My Friend - Bruce Lee

Sponsor Lou in Race For Life!

warjarrett

Thank you, Ben, for your concern for my safety. We all already know about how to protect the secondary by keeping it on position #2. There is no disagreement about this, and I assure you that I appreciate and practice it. The question, though, was about prolonging sensor life (not secondary life) when the Prism is to be stored for a long period. Can we be challenged one moment to think about avoiding a consistent drain of just one sensor (namely the #2), by repeatedly leaving that sensor under the load of the secondary? Well, my answer was an attempt to encourage people to think outside of the box, and not just repeat accepted dogma. If the accepted practice had no disadvantage at all, then there would be no reason to question it. But in this case, leaving the secondary on only position #2 (and for extended periods) does wear it out faster than the other cells. Is Chett's alternative valid? I think it is, but only if he is careful. There is nothing wrong with leaving the secondary on position S, if you are confident you will not be moving the Prism. And the advantage is that in this position, the secondary is connected to the unpowered head instead of a sensor. Do you mind if I explain this (even though you all know it)? An oxygen sensor is similar to a battery in the way it induces voltage by an internal chemical reaction? The more this reaction is stimulated, the faster the cell will wear out. Exposure to higher levels of oxygen or exposure to a load stimulates the reaction and thus causes cell life to diminish more rapidly. Thus, there is nothing wrong with the suggestion Chett posed (remove the load), except that he must understand (and it is obvious he does) his secondary will not be as well protected. Have I convinced anybody that I am sane?

Steve

FFS, the load is in the order of microamps. Listen to the wealth of experience that is telling you to move the cell if this bothers you. How ****ing hard is that?

__________________
WARNING: I contain occasional coarse language, extreme sexual references, nudity, and adult themes, which may offend some people - Usually churchy types.

jhaaja

Take the cells out from the Rebreather and connect the secondary to a voltage source with output around 50mV

All problems of the World solved

JH

caveseeker7

Don't think it's gonna make a difference, but in two or three years I went in and out of SMI's shop
in Hermosa Beach not once did I see PRISMs "stored" with dials anywhere but the #2 position.
That includes the rental fleet that SMI had at that time.
I do however remember Pete's reaction when someone would leave the dial on S or B.
It wasn't pretty.

But it's your rig, you can play yo-yo or bolos for all I care.
I think everyone else has gotten the point.

Just don't come bitching and whining when the extended storage period is due to a damaged analog gauge.

__________________
Cheers
Stefan


Be Water, My Friend - Bruce Lee

Sponsor Lou in Race For Life!

warjarrett

And thus, my sanity is still in question... my lifespan diving CCR too.

Mike

Dude - it's not accepted dogma, I've tracked cell voltage on my cells for a couple of years. I also make sure to leave them in the same position for an unrelated reason.
I always leave the secondary in position 2.

What I have personally found, (ie through real experience not just making shit up), is;
Cell 2 does not degrade quicker than any others.
SMI cells have a decent lifespan ( >18 months is my experience) so you will be replacing them all well before the 2/5ths of SFA load on cell two does anything.
The secondary has been jogged from position two a number of times, so if it started on 1 or 3 it would quite likely have ended up on S or B.
Dive gear gets knocked around at odd times, it gets shipped off late at night in a hurry after a few beers, people like playing with shit. So leave it in the most protected state all the time.

Once you have some experience you will have some old cells that are still putting out a decent voltage. If you still think it's a problem, take the 2 seconds to throw an old cell into the head when you are storing it. (I'd never do it because one day I'd forget to swap back).

Mike

__________________
Open ....... Closed
Mind ........ Loop

silent running

Not that it's news to anybody, but to put it in plain terms: cells do not age at the same rate, even if they are from the same batch, even if they are sequential, never mind the failure rates of individual cells. In otherwords, forget predicting the failure of a healthy, linear cell beyond say, the basic 6-20 month time frame.

So, from a cell life standpoint, who cares which sensor the 2dry dial is left at? It's barely loading a cell which may may not last for 6-20 months. Anybody want to guess how much leaving the dial on sensor 2 matters compared to switching the load around between different cells from a statistical POV? I know there's not a lot of things to go wrong with the Prism, but don't we have something more important we can worry about? -Andy

DaveC

A bit harsh isn't that mate... who pissed your cornflakes this morning? Gees its a simple question from someone that's new. We've all been there so lets not forget were we all came from. New people come to this board to pick up little tips and tricks from the experienced ones. Lets not scare the new ones away.

A question like this has nothing to do with safety in the water or the basic Rebreather protocols. He's just trying to figure out if keeping the secondary on a sensor pulls that much of a load to task the cells when in storage. A simple "keep it on the second second sensor" is all that was needed.

__________________
Dave

Any day in the water is better then any day in the office.

DaveC

No, but you have convinced us all that you're a PITA.

__________________
Dave

Any day in the water is better then any day in the office.