Universal galvanic sensors

[doctormike]

This CCR O2 sensor sensor shortage has got me thinking. Why does each rebreather have its own unique sensors? Why can’t that be standardized?

I’m sure that there is some elaborate engineering justification for it, but it seem that they are similar enough that most rebreathers could be designed to take a universal cell design. So you wouldn’t have these tiny markets for each model, which are extremely sensitive to any supply chain disruption.

If there was a standard galvanic cell, it would be much easier to buy cells. They would be cheaper because of larger production volumes. They would be fresher because you wouldn’t have distributers sitting on a small cache of one type waiting to sell them. And if you were away on a trip, your chances of borrowing a cell and saving your dive would go way up. Big groups could just buy a few extras and share the cost, much more efficient than everyone bringing their own. And companies that DID design their rebreathers to take a standard cell would have a big marketing advantage over those that didn’t.

We don’t use a special Meg O2 tank valve. There is no rEvo specific LP convector. No JJ 9 volt or AA battery. No Liberty sorb. Everything rechargeable has to eventually get power from a standard outlet.

And people don’t have big stashes of cells, so you don’t have to worry about a new design being backward compatible with existing sensors. That problem sunsets in a year.

Maybe I’m missing something?

 

[Jack Hammer]

Response times would need to be standardized too.

 

[rjack321]

Voltage is mostly standardized nowadays (9-13mv), there are a few older units which take high voltage sensors.
Oddly, the threaded end is basically standard, its the connector which isn't. But there are really only 2 types, molex and coax. And strong feelings on both side why one connector is better than the other.

Why? They are all close enough nowdays and measured in seconds not minutes anyway.

 

[doctormike]

But that’s the nature of a standard - competing designs have to get settled somehow, or we would still be fighting the war of the currents. No matter what the arguments for molex vs coax, the advantage of either is nowhere near as important as a standard would be...

 

[RainPilot]

I suspect its because only a tiny fraction of O2 sensors are destined for CCR. In the big bad world of chemical and gas analysis, there may be a 100 reasons to have different cells, aside from the "patent dodging" small variations that you get anyway. Those standards also aren't likely to change easily since updating an entire chemical plant to use a new type of wiring etc would be seriously pricy.

A CCR manufacturer has to guess which cell maker will still be in business and selling those same cells 20 years from now, so that users don't have a problem finding cells, and then design around those particular cells.

The MD-39 and variants are about the closest I suspect we will get to a "universal" cell standard, and even those are just very common and by no means in most CCR out there.

I share your pain Mike but I suspect we will have a complete change in how rebreathers work before we have standard sensors.

 

[tbone1004]

standardized cells in our world wouldn't change pricing or anything. Both connections are standard in their industrial applications as are both voltages. Even the Poseidon SSS is an industrial cell. They helped drive it, but there's a reason it's in the exact same form factor as a standard O2 cell and it has nothing to do with that size being optimum for the design, it's so they can sell it into industrial applications as a physical drop in.

 

[kelemvor]

standardized cells in our world wouldn't change pricing or anything. Both connections are standard in their industrial applications as are both voltages. Even the Poseidon SSS is an industrial cell. They helped drive it, but there's a reason it's in the exact same form factor as a standard O2 cell and it has nothing to do with that size being optimum for the design, it's so they can sell it into industrial applications as a physical drop in.

Do they sell it under a different name for industrial applications?

 

[The Chairman]

While a laudable idea, I don't see it happening either. Rebreather politics are just as bad as cave politics. If it's not you or yours, it's crap!

 

[JahJahwarrior]

It would be nice,
I enjoy the joke/memes about standards. Goes like this, can replace "oxygen sensor" with almost anything.
"Hey, there are 7 different competing oxygen sensor types, we need one standard that will replace them all!"
One year later
"Hey, there are 8 different competing oxygen sensor types, we need one standard that will replace them all!"

 

[broncobowsher]

There is one rebreather that they make adaptor harnesses for that lets you plug a molex cell into a coax breather. People have made it happen.

Wait until the solid state cell comes to market. A little switch on the side that will let you select what sensor it is trying to emulate.