URGENT: Can someone please explain the Uemis gas settings (gas limit / reserve)?

[DevonDiver]

I hope someone can help ASAP.

Just a quick query before I dive tomorrow.

A customer has the Uemis VDA computer. There is some confusion between the 'gas limit' and the 'reserve' settings. Can someone please explain what the 'gas limit' refers to? The 'reserve' seems common-sense (I think?).

Cheers!!

 

[Scubacastor]

- Gas limit is a first alarm that shows up on your screen while diving
- Reserve is the reference pressure used to calculate the remaining gas time.
- Gas limit is higher than reserve (mine is set at half tank pressure)

 

[DevonDiver]

So, that first alarm sounds when the remaining gas time reaches a level near the ascent time? Or something else?

What difference does changing the 'gas limit' make? Making it larger or smaller?

The reserve figure just triggers a (second) alarm when you reach it?

 

[Insta-Gator]

Gas limit is your "turn pressure" and does not effect the BTR (bottom time remaining) calculation (user setting.)
Reserve (back on boat PSI) is subtracted from starting PSI when BTR is caluclated.

 

[Scubacastor]

That may sound a trivial explanation but gas limit is triggered when you reach your set gas limit. There are no consequences except a big indicator on your screen that you must acknowledge.

A second alarm is triggered when you reach a preset remaining gas time which depends on your preset reserve requesting you to ascend.
A third alarm is triggered when you time to surface starts to be incompatible with you remaining dive time. At that point, the computer tells you to end your dive.

You can download the full uemis manual on their website in the support section.

 

[DevonDiver]

Thanks for the info, it is clearer now.

It's not my computer... is a customers. They don't have manual or internet access...and as a rather splendid instructor, I always aim to go a little further in what I can provide. Teaching a wreck course... so these functions have particular pertinence.

I did look at the uemis manual online, but there was no clear explaination of those terms and functions (that I could find after searching the site and reading the quick start guide and user manual).

So... let's see if I got this right....

Gas Limit is a user-defined warning, of no consequence, that is triggered when the pressure reaches the user defined limit. The obvious utilization is for a turn-point (i.e. set at 2000psi in a 3000psi tank... when using rule of thirds).

Reserve is also user-defined and indicates the minimum contingency volume. That could be 35bar/500psi or something like 1000psi (if using rule of thirds).

A third non-user-defined alarm is triggered when the divers time-to-surface approaches (?) the remaining gas time.

Have I got that correct?



btw.... it's a lovely computer. I am really impressed. Hope Uemis don't fold.

 

[BB1]

See comments below!

Gas Limit is a user-defined warning, of no consequence, that is triggered when the pressure reaches the user defined limit. The obvious utilization is for a turn-point (i.e. set at 2000psi in a 3000psi tank... when using rule of thirds). Spot on - exactly how I use it when cave diving or wrecks. The rest of the timee I set it for just under half tank pressure

Reserve is also user-defined and indicates the minimum contingency volume. That could be 35bar/500psi or something like 1000psi (if using rule of thirds).
The explanation I received from UEMIS, and testing confirmed it, was that the reserve is the pressure you want in your tank on the surface once the dive is finished! The SDA uses this to work out remaining gas time based on depth and breathing rate and also taking into account safety or deco stops on the way up.

A third non-user-defined alarm is triggered when the divers time-to-surface approaches (?) the remaining gas time. Yep see above comment. Once this alarm goes off start coming up and remaining gas time extends as you'd expect.

Have I got that correct?



btw.... it's a lovely computer. I am really impressed. Hope Uemis don't fold. They have folded!

 

[huexley]

btw.... it's a lovely computer. I am really impressed. Hope Uemis don't fold.

its over for uemis lets hope uwatrc will buy the brand... You can also have a look at the ostc mk2. ;-)