Integrated air "safety" reserve

[fdarden]

I noticed that my Atomic Cobalt has a safety reserve setting for the gas supply of 300 pounds incorporated by default into the computer. I am assuming that this setting will cause the dive computer to erroneously report the actual amount of air left in my tank. My mind is telling me to set this "feature" to zero. In my opinion, your air pressure is your air pressure. Not that you should ordinarily be so low on air that it would matter, but 300 extra pounds can be the difference between making a safety stop, or making a controlled emergency ascent. What do you guys think? My only hesitation in setting this to zero is that I wonder if the manufacturer has this as a fudge factor for pressure accuracy. While I strongly doubt it, we are talking air supply here. Im going to compare my dives as closely as I can today with my analog pressure gauge and hopefully answer my own question, but I would also like some experienced divers opinions. Thanks.

 

[navyasw02]

Is that 300psig an alarm setting? Regardless, I'd leave it. A safety stop isn't nearly as important as having enough air to breathe and safely make it to the surface.

 

[vladimir]

First, read--or reread, your manual. My computer also has a provision for a gas reserve, which it uses to calculate "remaining air time." It does not affect the pressure display, which shows actual tank pressure, without any "fudge factors." I would be surprised if yours is different in these respects.

 

[DiveMaven]

My AI computer is the same as Vladimir's....the psi in the tank is accurate, it is the air time remaining that counts down, acting as if 400psi is "0 time remaining". I just recently surfaced with only 325psi in the tank, with my computer telling me during my safety stop that I had "0 time remaining" a good part of the time. Since this was intentional on my part, and I was only in 30 feet of water when I had "1 minute remaining", I knew I had plenty of air for my stop and it was no big deal. It isn't something I routinely do, but there were cool creatures on the pinnacle, so I pushed my time a bit (and I was well within my NDL).

Read your manual, this is a great example of why you should know your computer.

 

[CPH]

My Luna has a simalar function. The difference is I can set mine to what I want.
I can tell the computer that my reserve is to be say 30bar and it will make sure I surface after all deco obligations with......30bar.
It is a GOOD thing not something you should get worried about.

 

[rhwestfall]

....... never mind - if I stop biting my tongue, evil things will come out.....

plan your dive, dive your plan....

 

[RonR]

I noticed that my Atomic Cobalt has a safety reserve setting for the gas supply of 300 pounds incorporated by default into the computer. I am assuming that this setting will cause the dive computer to erroneously report the actual amount of air left in my tank. My mind is telling me to set this "feature" to zero. In my opinion, your air pressure is your air pressure. Not that you should ordinarily be so low on air that it would matter, but 300 extra pounds can be the difference between making a safety stop, or making a controlled emergency ascent. What do you guys think? My only hesitation in setting this to zero is that I wonder if the manufacturer has this as a fudge factor for pressure accuracy. While I strongly doubt it, we are talking air supply here. Im going to compare my dives as closely as I can today with my analog pressure gauge and hopefully answer my own question, but I would also like some experienced divers opinions. Thanks.

You can change this value to whatever you want it to be, with a minimum value of 300 psi, a maximum of 999. It is a user defined setting. It is used only by the gas time remaining calculation, and does not affect the pressure display.
I'm sure you can understand why we don't allow it to be set below 300 psi- it would allow the gas time remaining to be a little too close to the edge.

Ron

From Page 17 of the manual:

Safety Reserve sets the tank pressure with which you wish to return to the surface. This
is used in diving by the Gas Time Remaining calculation, which shows the time you can remain at a depth while still returning to the surface with this reserve pressure, after making all deep, decompression, and safety stops.

 

[Hatul]

Why can't people just read the manual?

 

[vladimir]

Why can't people just read the manual?

I bought a DiveRite Nitek computer a long time ago. The front page of the manual said something like, "No time to read the manual? Flip to page 18 for the Quick Start Guide". I flipped to page 18, where it told me that I was a moron if I thought it was a good idea to use a dive computer without reading the manual in full. I don't totally agree with that, but I thought it was hilarious, and a good way to make their point.

 

[fdarden]

Thanks to those that took my question seriously and answered it. I will always try to help out new people myself in the future. Thats the great thing about a community - You can make friends and ask questions, and help friends by answering questions. I LOVE that concept.

Oh yeah and I DID read the manual - Front to back. Before I even turned the computer on. The manual is NOT CLEAR on this setting and its effect on actual PSI display. So maybe people should hold back non-helpful comments unless they TOO have read the manual.. But I digress..

Here is what the manual says for the record...

--
Safety Reserve sets the tank pressure with which you wish to return to the surface. This
is used in diving by the Gas Time Remaining calculation, which shows the time you can remain at a depth while still returning to the surface with this reserve pressure, after making all deep, decompression, and safety stops.
--