ANOTHER ALTERNATIVE FOR REBREATHER SENSORS

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

View attachment 557300

The manual seems pretty clear to only use their own. Why bother with anything else?

Good point. Maybe I'll ask Jan about that someday. I'm back to using JJ cells, and I agree, not much point in using something else.

I can see why they wouldn't let you substitute for the CE version, since CE depends on nothing changing between testing and use. I wonder if they feel the same way for the International version, which doesn't have CE.
 
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?
 
I'm afraid that Ken is just being difficult. You can lead a horse to water, but you can't make it drink.

For me, using 10 sensors a year, saving a few bucks on each sensor adds up and since I've been using AI sensors for the past 5 years, I already have a pressure pot to check my sensors.
I'll try Patrick's sensors, and will probably be very happy with them.

MIchael
 
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?

I come from the other point of view. You ask why I don’t think it will work. My reply is I see no evidence that it does actually work, just an expectation that if tested it would work. It sounds like a fair expectation, but weaker than actually testing.

I make software for a living. Part of the job is to make sure you have as much test coverage as possible. Testing at different levels inevitably reveals some things that need fixing. Eventually you get to deploy stuff and find more weird things where stuff that ‘should just work’ does not. Expect surprises.

I know there are CCR divers who are prepared to put up with weird cell behaviour, generally due to supply issues. Personally, I have enjoyed five years with only one cell which was remotely suspicious and have always been able to buy cells when I need them.

JJ, AP etc have years of history selling cells. They are part of their engineering effort to build the machine. The literally had to test them as a system to be allowed to sell them.

Testing, it is a great idea.

The issue you would have is doing significant testing over time, rather than just plugging in a set and doing a couple of dives, across the variety of machines you want to support.
 
Ken, I can understand your concerns but cannot agree.
Sensors, are like car tires, you can buy them over the internet for a fraction of what your car dealer is asking for them.
If I can get Michelin sensors for a fraction of what my manufacturer is asking for BF Goodrich sensors, I'll get the Michelin sensors. If I have reason to believe the Michelin sensors are better made, come with a testing certificate for each individual sensor and last longer too, I'd be a fool to buy sensors from the manufacturer, without an individual testing certificate, date of manufacture, etc.
With my AI sensor supplier I've never bought a sensor that was made more than 3 weeks ago and I hope that Patrick can offer the same level of service.

Michael
 
I come from the other point of view. You ask why I don’t think it will work. My reply is I see no evidence that it does actually work, just an expectation that if tested it would work. It sounds like a fair expectation, but weaker than actually testing.

I make software for a living. Part of the job is to make sure you have as much test coverage as possible. Testing at different levels inevitably reveals some things that need fixing. Eventually you get to deploy stuff and find more weird things where stuff that ‘should just work’ does not. Expect surprises.

I know there are CCR divers who are prepared to put up with weird cell behaviour, generally due to supply issues. Personally, I have enjoyed five years with only one cell which was remotely suspicious and have always been able to buy cells when I need them.

JJ, AP etc have years of history selling cells. They are part of their engineering effort to build the machine. The literally had to test them as a system to be allowed to sell them.

Testing, it is a great idea.

The issue you would have is doing significant testing over time, rather than just plugging in a set and doing a couple of dives, across the variety of machines you want to support.


I understand your concerns and I have been unsuccessful in easing them. I think that is largely due to your lack of knowledge in the design and manufacture of oxygen sensors. Either that, or you just enjoy arguing.

I could pick apart the information in your replies, continue to ask you questions that you cannot answer, ask you about accepting my bet ... but, I fear it is all a waste of time and energy and I would rather spend that time on others.
 
Ken, I can understand your concerns but cannot agree.
Sensors, are like car tires, you can buy them over the internet for a fraction of what your car dealer is asking for them.
If I can get Michelin sensors for a fraction of what my manufacturer is asking for BF Goodrich sensors, I'll get the Michelin sensors. If I have reason to believe the Michelin sensors are better made, come with a testing certificate for each individual sensor and last longer too, I'd be a fool to buy sensors from the manufacturer, without an individual testing certificate, date of manufacture, etc.
With my AI sensor supplier I've never bought a sensor that was made more than 3 weeks ago and I hope that Patrick can offer the same level of service.

Michael
Ken, I can understand your concerns but cannot agree.
Sensors, are like car tires, you can buy them over the internet for a fraction of what your car dealer is asking for them.
If I can get Michelin sensors for a fraction of what my manufacturer is asking for BF Goodrich sensors, I'll get the Michelin sensors. If I have reason to believe the Michelin sensors are better made, come with a testing certificate for each individual sensor and last longer too, I'd be a fool to buy sensors from the manufacturer, without an individual testing certificate, date of manufacture, etc.
With my AI sensor supplier I've never bought a sensor that was made more than 3 weeks ago and I hope that Patrick can offer the same level of service.

Michael

Hi Michael. You mentioned the testing certificate that is supplied by AI and when I saw they doing that (prior to you mentioning it) I kind of laughed. I have been distributing Teledyne oxygen sensors since 1999. I think in around 2000 we started selling rebreather sensors and ended when Teledyne pulled out of that market. I think they pulled out around 6 years ago, but might be slightly more. I would have to check my records to be positive. I still sell sensors for them for analyzers. Believe it or not, there are some people still using Teledyne sensors for rebreathers despite them not being approved for that application. When we first started selling rebreathers, everyone was using medical sensors because the market was so young. The only reason Teledyne came out with a diving sensor was due to the government getting upset with us selling medical sensors without a prescription. So, minor variations were made in addition to changing the label from medical to diving. The changes were insignificant, but used in marketing. The changes did not result in a sensor that improved performance is any way.

In fact, Teledyne had an issue with the conformal coating early on. It was too thick and it resulted in a blocked vent hole.

During the entire time frame I have been distributing oxygen sensors I never had to supply testing data. To give you an idea on just how great Teledyne is at making sensors, in the 20 years I have been selling their sensors (and I sold a lot of them), I know I have had less than 12 cells that fell under warranty.

Once Teledyne left the RB market, their was a large void due to the quality of the competition. In the case of AI, I imagine that they began providing test data on each sensor due to the problems they had and the reputation they were getting. If you make a good sensor, those documents are not necessary because each sensor should be consistently made the exact same way. Other factors that come into play are where you source your materials from. Example: You can test a sensor after assembly and it tests well. But, if you have inferior or lead that is not as pure as it should be, a couple months after testing, that sensor will begin to or completely fail.

To the best of my knowledge, I do not know of any manufacturer that does not have date codes on their sensors.

The longest I have seen a sensor still function that was not used was 5 years on a shelf. Most manufacturers have a shelf life of 2 years and the sensor should be put in use by then. I tell everyone one year. If the sensor does not come in a barrier bag, I would not feel comfortable with those time frames. And, I should note that some sensor mfgs do not use barrier bags. If a sensor mfg tells you the sensor is ready to use once the bag or container is opened, it is because they are not in a barrier bag and are continuously exposed to oxygen when on the shelf.

All sensors are similar in design. The differences that come into play are some proprietary designs, where they source their materials and the QA program they have in place.

Well, that is my two cents worth that I have accumulated in the last 20 years being in the business. Hopefully, you found some of the history or information useful or interesting.

Merry Christmas!

Patrick
 
Ken, I can understand your concerns but cannot agree.
Sensors, are like car tires, you can buy them over the internet for a fraction of what your car dealer is asking for them.
If I can get Michelin sensors for a fraction of what my manufacturer is asking for BF Goodrich sensors, I'll get the Michelin sensors. If I have reason to believe the Michelin sensors are better made, come with a testing certificate for each individual sensor and last longer too, I'd be a fool to buy sensors from the manufacturer, without an individual testing certificate, date of manufacture, etc.
With my AI sensor supplier I've never bought a sensor that was made more than 3 weeks ago and I hope that Patrick can offer the same level of service.

Michael

My car takes some tyres which are almost identical to the same sized tyres fitted to the equivalent Mercedes. They differ in a couple of letters at the end of a whole alphabet of part number. They are made by the same company but I suppose they are not identical. I have no idea what the difference is, I just buy, from either a main dealer, the bloke round the corner or the Internet, the exact one specified by the manufacturer.
 
..given the JJ ones work, why not just use them?

Resurrecting a zombie thread, since now I have a good answer to Ken's question! No idea when the JJ Vandagraph sensors will be available, and neither does the JJ manufacturer or the US distributor. DGX has no AI cells either.

SO, I was wondering if anyone had any real world experience with OxyCheq / AST cells since we last discussed this in December. It looks like I can get some of them.
 
Resurrecting a zombie thread, since now I have a good answer to Ken's question! No idea when the JJ Vandagraph sensors will be available, and neither does the JJ manufacturer or the US distributor. DGX has no AI cells either.

SO, I was wondering if anyone had any real world experience with OxyCheq / AST cells since we last discussed this in December. It looks like I can get some of them.

I just picked up two ast J.J. cells a week ago. My rib uses J.J. cells and one just hit its use by date. It works perfectly so I’m hesitant to switch it. But I’ll do as my instructors recommend in a few weeks and replace it. I’ll let you know how it goes. I was told the first batch had cords that were too short and annoyed people. Apparently that’s been addressed.
 

Back
Top Bottom