Quickest way to change gas on Perdix AI?

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Perdix manual: Rec-Nitrox-Mode-Perdix manual section 7.2 says

7.2. Select Gas
The Select Gas menu allows setting the active gas from the list of gases that are currently programmed. Up to three gases may be programmed in the Nitrox Recreational mode.

So the proposal to define multiple gases and then select the one closest to to the actual is possible within the above limit. I leave my defined gases as 21, 32, & 36 percent and as other posters has stated typically Nx32 the actual is 31-33 so "close enough".
 
For me, I just wanted to have all the nitrox % in logs, so I just setup the 3 gas’s, very simple easy setup. One dive I had a 36% tank, just switch over and set real easy. I setup 21,33,34 Just came back from cayman and logged 26 dives .... all those settings were what I had except for that one dive.
 
Thanks again for the suggestions. I started out in the system settings enabling and disabling, but later into the dives I just left both nitrox settings enabled and switched via the Select Gas menu. I figured for rec diving it wouldn’t ask me to switch gases, and it didn’t.

Interesting thing is that on the deepest dive we did, down to 107’, the Perdix gave me a five-minute safety stop. It’s in Adapt mode for safety stops.
 
Interesting thing is that on the deepest dive we did, down to 107’, the Perdix gave me a five-minute safety stop. It’s in Adapt mode for safety stops

In the Nitrox Recreational Mode - Perdix User Manual on page 19 Section 8.2 Deco Setup under Safety Stop it states that in the adapt mode it will give you a 5 minute stop if you go below 100'.

Safety Stop
The Safety Stop setting can be set to the following values:

• Off
• 3 minutes
• 4 minutes
• 5 minutes
• Adapt

When using the Adapt setting, a 3 minute safety stop will be used, unless the dive exceeds 100ft (30m) or the NDL falls below 5 minutes, in which case a 5 minute safety stop is used
.

Cheers - M²
 
In the Nitrox Recreational Mode - Perdix User Manual on page 19 Section 8.2 Deco Setup under Safety Stop it states that in the adapt mode it will give you a 5 minute stop if you go below 100'.

Safety Stop
The Safety Stop setting can be set to the following values:

• Off
• 3 minutes
• 4 minutes
• 5 minutes
• Adapt

When using the Adapt setting, a 3 minute safety stop will be used, unless the dive exceeds 100ft (30m) or the NDL falls below 5 minutes, in which case a 5 minute safety stop is used
.

Cheers - M²
Yeah, thanks. Just found it interesting since I’ve never seen anything other than three minutes for rec computers.
 
I don't do any gas switching during a dive and I use my perdix AI in rec mode.
When I go on charter dive boats, the nitrox tanks are waiting for me on the boat. I never really know what mixes they will give me... anywhere from 32 to 36. They are labled with tape and sharpie and I confirm this with an analyzer.

I don't use the SELECT GAS feature at all.
I go to DIVE SETUP and then DEFINE GAS. I keep the second and third gases and 00% and off (in purple) all the time and this way, they don't even appear as options in SELECT GAS.
So before almost every dive, I go to DIVE SETUP and DEFINE GAS and just modify the first gas (it's the only one that's on).
 
Late to the game on this but I have a question that somewhat related to this rather than starting a new discussion.

With the Perdix AI, say you're diving two tanks. It doesn't really matter what configuration, but let's just say a single AL80 w/ 21% and a AL40 w/ 40%.

If you have wireless transmitters on both tanks, can you assign the gas % for the transmitters as well, so that when it detects a pressure change in one it's switch to that gas?

If not, wouldn't this be a beneficial feature to have?
 
If you have wireless transmitters on both tanks, can you assign the gas % for the transmitters as well, so that when it detects a pressure change in one it's switch to that gas?

No, I don't think there is such a feature. Might work in some ideal situations, but would be totally screwed when you have anything unusual happening like free flowing stage regulator, gas sharing etc.
 
No, I don't think there is such a feature. Might work in some ideal situations, but would be totally screwed when you have anything unusual happening like free flowing stage regulator, gas sharing etc.

Good point. I would think that could be written into the software. If the pressure drops to fast it would recognize it or flash an ERROR message you could button tap to acknowledge. I haven't used Ai before so I don't know how much a single breath registers digitally compared to analog. I'm sure the brains that write software could build it so it can differentiate between a continuous flow compared to a intermittent drops in the pressure.

I'm not a programmer but I would think this is something that could be done.

Not sure about gas sharing. Again, maybe a button push where if it registers simultaneous or close drops in pressure from two different tanks/transmitters it could flash a message to acknowledge gas sharing or a leak. If you're gas sharing, you're pretty much ending the dive anyway, right?
Although, don't some instructors run transmitters on their student's tanks to monitor their gas? Could be a pre- / post-dive setting.
 
The transmitter has a 4 second transmit interval and it probably averages quite alot too. Of course it is possible to desing a transmitter and a computer which recognize different breathing patterns etc. but the current very reliable transmitter probably doesn't support it well.
To me manual gas changes seem superior to automated ones with possible error messages that have to be acknowledged.
It is the divers responsibility to always know what they are breathing, and the gas change in Shearwaters is really easy and quick (especially if you choose the new style from advanced settings).
In rebreathers ppO2 is continuously measured from the loop and this information is used for deco calculations, so there your idea is more or less in use.
 

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