ANOTHER ALTERNATIVE FOR REBREATHER SENSORS

[Patrick]

Either to maximise income, or because they tested them with their own (or at least specified and branded) cells. Or a combination of the two.

PS, given the JJ ones work, why not just use them?

I am sure they tested them. The main reason is $$$. I am not twisting your arm, use what you want to use. In the end, the market not one individual will determine what they prefer to use.

 

[taimen]

The reason is probably CE (in addition to $$$, but I don't see them making too much money with cells).
I can get fresh JJ branded cells from my LDS for 100€ each (including 24% vat/sales tax).
Thus they are not overly expensive here.
I definitely welcome options when buying new cells and won't pay attention to the warnings in the manual if good quality alternative cells are available. The JJ branded cells seem to be high quality, and not that much more expensive compared to currently available alternatives.

 

[KenGordon]

Sensor performance, in the context of the actual RB, is quite important. The only way to know if something works is to test, preferably quite extensively. I wonder why mike would use non JJ sensors in his JJ. To be blunt, in your case you are saying they will be available ‘real soon now’ when the courier turns up, rather than when you are finished an extensive set of acceptance testing and characterisation.

Worst way I spend £300/year on sensors. Say yours are half that, I can save £150/year. Really, why bother?

Mike has already tried non JJ cells, he seems like a sensible bloke, so I wonder why.

 

[Patrick]

Sensor performance, in the context of the actual RB, is quite important. The only way to know if something works is to test, preferably quite extensively. I wonder why mike would use non JJ sensors in his JJ. To be blunt, in your case you are saying they will be available ‘real soon now’ when the courier turns up, rather than when you are finished an extensive set of acceptance testing and characterisation.

Worst way I spend £300/year on sensors. Say yours are half that, I can save £150/year. Really, why bother?

Mike has already tried non JJ cells, he seems like a sensible bloke, so I wonder why.

We have been testing the AST-22D sensors for the last several months in the Florida caves. They are the same output as the JJ version. The only difference between them is the connector that is used.

In the past we distributed Teledyne sensor for rebreathers and they left a huge void once they left the market. That said, I know people that still use them because of their performance and reliability because they have experienced the other sensors that are available.

I could have used other manufacturers to make RB sensors when Teledyne ended, but did not for a reason.

Furthermore, if a manufacturer can produce and has produced a reliable sensor, it makes no difference whether it is used in an analyzer or rebreather.

But, I will make it easier for someone thinking about using the AST sensors for their rebreathers. Anyone purchasing any for the JJ will get them at $55 each and shipping. This offer will expire at the end of January 2020.

if interested, please contact me via my email ... oxy@oxycheq.com

 

[KenGordon]

They are the same output as the JJ version. The only difference between them is the connector that is used.

So, have you tested them with actual JJs or are you assuming that because the specs are the same that once the connector is changed it will all be lovely?

 

[Patrick]

We have not put them in an actual unit. However, we did test a JJ sensor against an AST in the lab and if it works in a lab environment it will work in the rebreather. As I said before, the same sensor with a different connector has been tested almost daily on long cave dives.

And, we continue to test some of the initial run of sensors in the lab to check on their performance.

I have been working with sensors since 1999, now over 20 years and dove rebreathers when the only CCR available were MK15s. I have seen great, average and bad sensors throughout that time frame.

With the information I have provided you if you think that our replacement sensor does not work in a JJ rebreather I will be happy to wage a bet with you.

 

[KenGordon]

We have not put them in an actual unit. However, we did test a JJ sensor against an AST in the lab and if it works in a lab environment it will work in the rebreather. As I said before, the same sensor with a different connector has been tested almost daily on long cave dives.

And, we continue to test some of the initial run of sensors in the lab to check on their performance.

I have been working with sensors since 1999, now over 20 years and dove rebreathers when the only CCR available were MK15s. I have seen great, average and bad sensors throughout that time frame.

With the information I have provided you if you think that our replacement sensor does not work in a JJ rebreather I will be happy to wage a bet with you.

Hmmm, so I bet my life (ok, an exaggeration assuming I dive properly) that the cell works and you bet what?

You are really selling things to plug into a box based on measurement against an equivalent being ok, without actually trying it?

 

[Patrick]

The reason is probably CE (in addition to $$$, but I don't see them making too much money with cells).
I can get fresh JJ branded cells from my LDS for 100€ each (including 24% vat/sales tax).
Thus they are not overly expensive here.
I definitely welcome options when buying new cells and won't pay attention to the warnings in the manual if good quality alternative cells are available. The JJ branded cells seem to be high quality, and not that much more expensive compared to currently available alternatives.

The main cost of making a sensor is labor. Additional costs would be the connector used. As an example, Molex connectors are cheap in comparison to the variety of coax connectors. Often, a manufacturer of analyzers or rebreathers wants a sensor like nothing else on the market so they can supply all the replacement sensors.

Hmmm, so I bet my life (ok, an exaggeration assuming I dive properly) that the cell works and you bet what?

You are really selling things to plug into a box based on measurement against an equivalent being ok, without actually trying it?

I don’t expect YOU to bet your life. Th

 

[rjack321]

Sensor performance, in the context of the actual RB, is quite important. The only way to know if something works is to test, preferably quite extensively. I wonder why mike would use non JJ sensors in his JJ. To be blunt, in your case you are saying they will be available ‘real soon now’ when the courier turns up, rather than when you are finished an extensive set of acceptance testing and characterisation.

Worst way I spend £300/year on sensors. Say yours are half that, I can save £150/year. Really, why bother?

Mike has already tried non JJ cells, he seems like a sensible bloke, so I wonder why.

I have been using ISC sensors for 5+ years. Leon individually tests them to ppO2 of nearly 3.0. He warrantees them for a year with free exchange. The molex connector on the back fits my Meg and my Kiss.

Yet when one failed in FL I didn't have a spare <that day>. I wasn't going to have an ISC cell overnighted to FL. So I found an AI and used it instead, it was terrible and died a fast death after about 15 hours. It might have been under warranty but I had no desire to use one again unless forced to. I would have gladly put one of @Patrick 's AST sensor in my Meg even without it being tested in my exact unit. Its a lead acetate battery with a specified mV output... I don't know what "extensive testing" means to you but if the membrane is rated to UW use and the temperature compensation board is properly coated, I would have no problems using it. Especially one as a replacement, since I can see how it performs next to my other normal cells.

 

[Patrick]

The main cost of making a sensor is labor. Additional costs would be the connector used. As an example, Molex connectors are cheap in comparison to the variety of coax connectors. Often, a manufacturer of analyzers or rebreathers wants a sensor like nothing else on the market so they can supply all the replacement sensors.

The main cost of making a sensor is labor. Additional costs would be the connector used. As an example, Molex connectors are cheap in comparison to the variety of coax connectors. Often, a manufacturer of analyzers or rebreathers wants a sensor like nothing else on the market so they can supply all the replacement sensors.


I don’t expect YOU to bet your life. Th

/QUOTE]

Hmmm, so I bet my life (ok, an exaggeration assuming I dive properly) that the cell works and you bet what?

You are really selling things to plug into a box based on measurement against an equivalent being ok, without actually trying it?

I don’t expect you to be betting your life because I don’t plan on you using the AST sensors.

Those diving them will be evidence of them working. I say they work and you believe they don’t. How about $2000 USD as a wager?

NEDU tests a number of sensors out of a batch in a lab environment and then they approve them for use in rebreathers. Certainly, some of their equipment exceeds that of any sensor mfg. But, if a sensor is designed and manufactured properly, they will be linear and perform as expected.

I have told you we been testing and diving AST-22D sensors and the only thing required to have it work in a JJ rebreather is to change to a different connector. For some reason, you have concern and feel it should be tested in an actual JJ rebreather and despite the fact that we have tested a JJ sensor against an AST version of it.

My question to you is why do you think it will not work when they have the same threads, almost identical dimensions, same output and same connector?