Will Air Integration in dive computers replace the SPG?

[agilis]

That's rate of change aka derivative aka slope, gradient being a synonym for slope.

Do you use different SPGs for different size tanks? The needle will move very differently when breathing down an 80-gallon tank vs a .5 cf pony. You can program the computer to compensate for that.

I am curious as to how they progammed the IP drop (?) NetDoc says his computer detects and warns about.

Of course the needle drops more rapidly, all other things being equal, in a smaller tank. That's a given, glaringly obvious, not requiring any thought other than the obvious understanding that a 80 cf tank will move the needle at approximately half the rate of a 40cf tank, and the diminishing time element will be more precipitous with the smaller tank.

A different SPG? Are you really serious?The reasoning involved in this concept completely eludes me. An SPG measures pressure, which translates to available gas only in the context of a known volume capacity. Requiring a computer to do this kind of rate of change calculation means the diver is not using his brain.

There is a lot of that going around, I suppose.

I did quite well in trigonometry, and I understand the use of gradient in math as well as in topography.

 

[agilis]

Correct me if I'm wrong, but isn't it advised to service your SPG every year like you would any other piece of equipment. So if the battery (rechargable would be best) lasts for an extremly long time (my experience so far) then the transmitter may not require any more service than what would be required of an SPG. Which would be nothing more than a o ring swap and battery charge/replacement.

Very very little involved in 'servicing' a mechanical SPG. Number of hours of use more significant than passage of time.

 

[Kevrumbo]

Batteries are for vital tools like lights and Personal Dive Computer instrumentation (and if needed a hose connected PDC w/ AI) --again why the added expense & unnecessary application of them on an electronic wireless transducer AI when a conventional non-battery SPG will work just as well and reliably?

 

[CT-Rich]

I have a Aeris 500AI computer. It isn't wireless but it does have the feature of being able to give me minutes remaining at a given depth as an alternative to pressure. You don't really need to know the size of the cylinder because time is being calculated based on the rate that the air is being consumed off the tank. For a lot of NDL diving this is really all I need. A quick press of the button and I can see my actual pressure. It was set up based zero minutes being equal to 600 psi. I can toggle back and forth between the real pressure and the estimated time remaining. What I like about the data I am getting is that I can look at my computer and tell get real time feed back about my breathing rate. A mechanical SPG simply can't do that. I know Kevrumbo will now tell me that I should have the zen diving perfection to self monitor by counting my breaths and, knowing my lung volume and gas volume exchange rate of an African swallow flying while home with a coconut be easily able to calculate my low SAC...... Anyway I could survive without it, but I appreciate the data being relayed in real time in a format that is easily interpreted. This data is actually very convenient in improving my sac since I get feed back in real time about my exertion.

I am not sure what all the apprehension is about Battery life is. I have two seasons with this particular dive computer and the batteries are still going strong. Follow the manufacturers advice on replacement (once year is probably adaquate.

 

[Kevrumbo]

I have a Aeris 500AI computer. It isn't wireless but it does have the feature of being able to give me minutes remaining at a given depth as an alternative to pressure. You don't really need to know the size of the cylinder because time is being calculated based on the rate that the air is being consumed off the tank. For a lot of NDL diving this is really all I need. A quick press of the button and I can see my actual pressure. It was set up based zero minutes being equal to 600 psi. I can toggle back and forth between the real pressure and the estimated time remaining. What I like about the data I am getting is that I can look at my computer and tell get real time feed back about my breathing rate. A mechanical SPG simply can't do that. I know Kevrumbo will now tell me that I should have the zen diving perfection to self monitor by counting my breaths and, knowing my lung volume and gas volume exchange rate of an African swallow flying while home with a coconut be easily able to calculate my low SAC...... Anyway I could survive without it, but I appreciate the data being relayed in real time in a format that is easily interpreted. This data is actually very convenient in improving my sac since I get feed back in real time about my exertion.

I am not sure what all the apprehension is about Battery life is. I have two seasons with this particular dive computer and the batteries are still going strong. Follow the manufacturers advice on replacement (once year is probably adaquate.

If you need AI for your comfort & safety, then fine . . .good diving to you.

My pressure SAC rate is 1 bar/min per ATA for my double AL80's, and do not require any more functionality than an analog SPG, an elapsed dive timer and my depth in meters from a bottom timer/dive computer to figure real time gas consumption. I do not need an AI feature to multiply depth in ATA by "one" and display remaining pressure in bar, when I can do the calculation quicker in my head by inspection than futzing with pressing a button.

My pressure SAC rate is 2 bar/min per ATA for my single AL80, and do not require any more functionality than an analog SPG, an elapsed dive timer and my depth in meters from a bottom timer/dive computer to figure real time gas consumption. I do not need an AI feature to multiply depth in ATA by "two" and display remaining pressure in bar, when I can do the calculation quicker in my head by inspection than futzing with pressing a button.

(Good diving to me. . .)

 

[Centrals]

I need a spg to tell me the content in my breathing tank. What else do I need? Nada.

Good diving to you if you require more info to satisfy your need.
Good diving to the rest if they think a spg is all they need.

 

[Divetech99]

If you need AI for your comfort & safety, then fine . . .good diving to you.

My pressure SAC rate is 1 bar/min per ATA for my double AL80's, and do not require any more functionality than an analog SPG, an elapsed dive timer and my depth in meters from a bottom timer/dive computer to figure real time gas consumption. I do not need an AI feature to multiply depth in ATA by "one" and display remaining pressure in bar, when I can do the calculation quicker in my head than futzing with pressing a button.

My pressure SAC rate is 2 bar/min per ATA for my single AL80, and do not require any more functionality than an analog SPG, an elapsed dive timer and my depth in meters from a bottom timer/dive computer to figure real time gas consumption. I do not need an AI feature to multiply depth in ATA by "two" and display remaining pressure in bar, when I can do the calculation quicker in my head than futzing with pressing a button.

(Good diving to me. . .)

That translates to approx 22 liters per minute?

 

[Kevrumbo]

That translates to approx 22 liters per minute?

Yes!. . .my cold water SAC-RMV is 22 liters/min per ATA.

Double AL80's have a Metric Tank Rating of 22 liters/bar.

22 liters/min*ATA -divided-by- 22 liters/bar equals: 1 bar/min per ATA.

Point is, you don't need AI to multiply with a unity/identity integer like "1" to figure out your real time gas consumption at depth ATA (Hint: 1 multiplied by a number is simply that number).

And I'd rather have the reliable & simple utility of an analog mechanical SPG instrument over an electronic battery powered digital AI module.

 

[CuzzA]

Everyone is so quick to point out how incredibly reliable the SPG is so I started searching the net last night for SPG failures and there are a ton of stories of divers going OOA due to a stuck needle (many right here on SB), other stories of hose failures, spool failures and plastic/glass failures. I'm not so convinced they're as reliable as some have claimed on this thread. You really have to wonder how many of those diver deaths who were never found again are attributed to being OOA due to a stuck needle.

What an absolutely terrible way for an important gauge to fail. Everyone can brag how good of a diver they are and they would recognize a stuck needle during a dive because they can do simple math, but not everyone is as good as you, dives as often as you or has the experience to recognize such a failure like you. I realize SB is made up of a lot of experienced divers, however, the same can't be said for everyone who participates in scuba diving around the world. Maybe today's AI is in fact way more reliable and if that's the case than no one can argue against the technology. (Note when I say "you" I'm using it as a general term for the reader and not directed at anyone specifically.)

I'm going to start a poll thread on this subject in the future and I realize it's not scientific, but I came across this thread on a different forum and thought it was worth sharing. Note that 84% of the vote had some sort of failure with their SPG. I don't know if it's ok to link another forum, if not and a mod removes it, perhaps we can just leave the screen shot of the poll results.

http://www.cavediver.net/forum/showthread.php/29286-SPG-failures

 

[AJ]

View attachment 366066 You really have to wonder how many of those diver deaths who were never found again are attributed to being OOA due to a stuck needle.

That's not SPG failure, that's diver failure. Big difference. AI or SPG does not matter if a diver is not aware of issues. However, I'am sad to think a diver would be killed because of some minor failure. That's truly sad if it were the case. Never ever trust your instruments, be a thinking diver! That's what safety is all about. It does make me sad how some people seem to rely on some instrument to get home save.

View attachment 366066I'm going to start a poll thread on this subject in the future and I realize it's not scientific, but I came across this thread on a different forum and thought it was worth sharing. Note that 84% of the vote had some sort of failure with their SPG. I don't know if it's ok to link another forum, if not and a mod removes it, perhaps we can just leave the screen shot of the poll results.

Where's the poll on AI failures? Statistics can prove everything you want, but do not prove anything by themselves