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Thread: Wes Skiles wrongful death suit

  1. #111
    RBW Member tcascione is a jewel in the rough tcascione is a jewel in the rough tcascione is a jewel in the rough tcascione is a jewel in the rough tcascione is a jewel in the rough tcascione is a jewel in the rough tcascione is a jewel in the rough tcascione's Avatar
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    Re: Wes Skiles wrongful death suit

    We old fat guys salute you. Since we are a substantial portion of the market we should be entitled to some design consideration

  2. #112

    Re: Wes Skiles wrongful death suit

    Hi Andy,

    Sorry for the delay - I didn't notice your post, my apologies.

    Bearing in mind that I'm not a cell expert...

    Quote Originally Posted by silent running  View Original Post
    1) I'm not familiar with these particular cells, but from the looks of it, is the sensor face actually surrounded by a collar which could trap and hold water??? If so, it's a very bad design for a CCR application. I wonder if a cell with a curved face would be the best design as it would increase the surface area in which to read, and would make it even harder for a meniscus to form...
    You could do that, but the collar also helps the teflon membrane making a good seal and protects it from damage. If it was exposed you'd increase the risk of it getting damaged or unglued. Increasing the surface area is problematic as well, because it would proportionally reduce the cell life, and we all know how some rebreather divers are likely to deal with the extra expense. You could increase the thickness of the membrane (there's actually two) to address that, but then you'd increase the latency. That's not to say the design couldn't be improved. The way I see it coating the inside of the collar with teflon would much reduce the cell's ability to retain water, for instance. But one has to be careful to not overoptimise one aspect at the expense of others.

    Quote Originally Posted by silent running  View Original Post
    3) All cells have to cope with 100% humidity and thus some amount of water on the face during operational life, and obviously they do this to some degree of reliability or there would be no CCR diving. But does a cell's MV output have a threshold below which it might still read a change in PO2 in perfectly dry conditions, but not have enough sensitivity to do so through even a very thin layer of water? Does a cell's ability to cope with water vapor specifically degrade as the MV output decreases?
    Given the same cell general design is used to measure O2 concentration in water, in wastewater treatment, for instance, I'd say no.

    Quote Originally Posted by silent running  View Original Post
    2) What orientation would the diver of your unit need to be in in order to replicate gravity holding water on the face of all 3 cells? Are all 3 cells oriented the exact same way in your unit? In other words, is it even possible that all 3 cells could ever be all facing the same way to allow water to sit on the face with full gravity?
    I'm with you. No, in my machine (JJ), the cells generally face downwards (ish), in different directions.

    Cheers,

    Matthieu
    Last edited by emmbee; 18th September 2016 at 02:00.

  3. #113
    Mature mouth breather silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running's Avatar
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    Re: Wes Skiles wrongful death suit

    Quote Originally Posted by emmbee  View Original Post
    Hi Andy,

    Sorry for the delay - I didn't notice your post, my apologies.

    Bearing in mind that I'm not a cell expert...
    Hi Mathieu, sorry I must also apologize for the late reply, been extra busy. Thanks for your detailed reply.

    Quote Originally Posted by emmbee  View Original Post
    You could do that, but the collar also helps the teflon membrane making a good seal and protects it from damage. If it was exposed you'd increase the risk of it getting damaged or unglued. Increasing the surface area is problematic as well, because it would proportionally reduce the cell life, and we all know how some rebreather divers are likely to deal with the extra expense. You could increase the thickness of the membrane (there's actually two) to address that, but then you'd increase the latency. That's not to say the design couldn't be improved. The way I see it coating the inside of the collar with teflon would much reduce the cell's ability to retain water, for instance. But one has to be careful to not overoptimise one aspect at the expense of others.
    Respectfully, I must disagree, I still think the collar is more - than +. The AI higher output cells used in the Prism 1 and MK's have no collar, and only the smallest raised area around the border of the cell face. In 14 years of diving, I have never seen one of those membranes punctured, or delaminated. I have also, to my knowledge, never had water vapor related cell reading errors. Any bad readings came from cells aging out, sudden full on failures or a bad connection at the molex connector.

    I'll guess that you are right about the surface area issue.

    Quote Originally Posted by emmbee  View Original Post
    Given the same cell general design is used to measure O2 concentration in water, in wastewater treatment, for instance, I'd say no.
    I'm not sure I follow this idea, wouldn't a cell designed to measure O2 in wastewater have different design objectives to one which measures O2 in mixed gas, owing to the differences in densities and distribution of O2 in the mediums?

    Thanks, -Andy

  4. #114
    So many CCR So little etc Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase's Avatar
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    Re: Wes Skiles wrongful death suit

    In 2000 I started to consider some properly deep dives and I seriously looked into CCR but the Inspo Classic was killing people by just being looked at and so I lusted after a Mk15.5 or the ultimate a CIS Luna I am prety sure i was looking at 10K+ investment and I couldent realy afford it

    A few years later I doscovered the KISS which made it properly affordable

    The Inspo classic was still killing people in droves but I was starting to hear it might not be the units fault and against my better judgement my buddy convinced me to get one.

    For under 5K I could get a unit and training package.



    CCR now are becoming prety bloody expensive and I blame this partly on CE cost and partly on the seeming deturmination for CCR divers to own units that wipe there arse for them

    I cant deny that thers been some good stuff come out of CE like an understanding of WOB and development to improve it, and thers been good progress in the electronics with things like the Sheerwater Controler but I do feel theres too much focus on expensive techno wizardry and its pushing CCR out of reach for many.


    If you want a car with auto parking ,,,,fine. Not my cup of tea and I dont feel the need personaly but as long as its an option great knock your self out.

    But i do feel a danger that we are promoting a dependance on sich toys far too much

    Id much rather see a root and branch re think on training as the focus of our attention

  5. #115
    RBW Member broncobowsher is on a distinguished road broncobowsher is on a distinguished road broncobowsher's Avatar
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    Re: Wes Skiles wrongful death suit

    While I don't care for cars to park themselves, I do like that cars have automatic spark advance. You don't have to adjust the spark by hand. And fuel injection makes them start and run a lot better, cleaner and lots more power as well.


    So at what point do you accept some technology and reject others?


    I know some people who think the carburetor is the best thing ever, even if it rarely is working right.

  6. #116
    So many CCR So little etc Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase's Avatar
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    Re: Wes Skiles wrongful death suit

    Quote Originally Posted by broncobowsher  View Original Post
    While I don't care for cars to park themselves, I do like that cars have automatic spark advance. You don't have to adjust the spark by hand. And fuel injection makes them start and run a lot better, cleaner and lots more power as well.


    So at what point do you accept some technology and reject others?


    I know some people who think the carburetor is the best thing ever, even if it rarely is working right.

    At the point where it becomes superflous

    like auto parking or a cell age warning system

  7. #117
    Mature mouth breather silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running has a reputation beyond repute silent running's Avatar
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    Re: Wes Skiles wrongful death suit

    I'm with Mark, the more automation, the more the diver is disconnected from the critical functions of the unit. CCR divers cannot afford to be even a little out of touch with their unit's critical functions, meaning cell behavior/health, gas addition and PO2 monitoring.

    Car/CCR analogies really only apply to convenience features like EFI or power steering because cars do not routinely function as life support. Sure, when things go wrong operators can be hurt or killed, but even then there are things like airbags and seat belts to help them survive a crash due to component failure. Which is statistically rare, thanks to market driven big budget engineering. But even driving a race car is not trying to breathe underwater. I don't think CCR manufacturers will ever have the resources of car manufacturers who make 100's of millions in revenue. So, we are our own safety net. If you think a dive gear manufacturer can guarantee your safety at all times with a bunch of snazzy electronics meant to operate under thousands of pounds of salt water, you are fooling yourself, possibly to death... -Andy

  8. #118
    RBW Member udtabn is just really nice udtabn is just really nice udtabn is just really nice udtabn is just really nice udtabn is just really nice udtabn is just really nice udtabn is just really nice udtabn is just really nice udtabn is just really nice udtabn is just really nice udtabn's Avatar
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    Re: Wes Skiles wrongful death suit

    gotta say mark makes a good case.......

  9. #119

    Re: Wes Skiles wrongful death suit

    Hi Andy,

    I wasn't defending a particular design, I was merely pointing out that, well, this is engineering, you have to make compromises. Stating from the get go that this or that is unsuitable may not be the right approach.

    Quote Originally Posted by silent running  View Original Post
    I'm not sure I follow this idea, wouldn't a cell designed to measure O2 in wastewater have different design objectives to one which measures O2 in mixed gas, owing to the differences in densities and distribution of O2 in the mediums?
    Why? You calibrate them in air and stick them in the water, done. What matters is the ppO2. That the gas is dissolved is not relevant. You can clearly see in the pictures I posted that the cell full of water measures the ppO2 in the water (at equilibrium with the ppO2 in the atmosphere) just fine. It's 'just' measuring the wrong thing for our purpose ;).

    Cheers,

    Matthieu

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