Perdix AI

[tursiops]

the water proof cap you put on the reg after removal, to seal the reg input from the tank. For those that give thier reg a long purge to blow it dry it chills the reg body ;It then warms up and turns on the AI. some remove regs from tank and instantly put on a 1" rubber ball type thing and others are like TP's with a spare oring in it. if it seals tightly the reg warms up and pressure builds and ultimately turns on the AI xmitter you just have to purge the secondary every few minutes untill no more purging happens after removal. Same thing happens when you shut of your tank air at the setup table you have to purge to shut down the xmitter. easiest way to monitor is to watch your puter and see if it is again xmitting PSI. Hopefully xmitters turn on at higher pressures than years ago. if not it is something to watch for. Ive gone through too many batteries because of that. Another erason I no longer use xmitters. NOthing says crap more than taking the reg out of the bag loosening the yoke and hearing a psssst.

I'm extremely skeptical that you can build up 120 psi (over 8 ATM) to turn on the Pelagic MH8A transmitter by doing what you describe. I'm skeptical to the point of calling this a myth...no, plain BS.

 

[Glenn Williams]

the water proof cap you put on the reg after removal, to seal the reg input from the tank. For those that give thier reg a long purge to blow it dry it chills the reg body ;It then warms up and turns on the AI. some remove regs from tank and instantly put on a 1" rubber ball type thing and others are like TP's with a spare oring in it. if it seals tightly the reg warms up and pressure builds and ultimately turns on the AI xmitter you just have to purge the secondary every few minutes untill no more purging happens after removal. Same thing happens when you shut of your tank air at the setup table you have to purge to shut down the xmitter. easiest way to monitor is to watch your puter and see if it is again xmitting PSI. Hopefully xmitters turn on at higher pressures than years ago. if not it is something to watch for. Ive gone through too many batteries because of that. Another erason I no longer use xmitters. NOthing says crap more than taking the reg out of the bag loosening the yoke and hearing a psssst.

Then something is wrong with your transmitter. The transmitter will shut off after awhile when no fluctuation in pressure exists.

Glenn

 

[tursiops]

Then something is wrong with your transmitter. The transmitter will shut off after awhile when no fluctuation in pressure exists.

Glenn

?? The specs for the MH8A say it turns off when the pressure drops below 50 psi for 4 minutes. Nothing about shutting off just because there are no pressure fluctuations.

 

[Glenn Williams]

Ok.

 

[NAM001]

?? The specs for the MH8A say it turns off when the pressure drops below 50 psi for 4 minutes. Nothing about shutting off just because there are no pressure fluctuations.

that explains a lot if it has 4 minutes to get 50 psi apain to keep the battery on. I had to learn to remome the reg and not put the dust cap on for several minutes to a half hour. How long actually needed
??? I dont know. I used the computer to identify when it quit transmitting. In addition most all my AI units would end up being 300 psi off at teh low end I think ,,by end of year and had to send in for PSI sensor replacement for about 120$ a crack. It would say 0 psi when it had 300 psi in the tank. So a question I then have. is the shut down or turn on calculated 130 psi and 50 psi or a psi difference relation to say the last shut down. For the guy that called BS this may be an explanation as to why mine did this. Not just one of them all of them I have had 4 all ltogether and only 2 in the drawer now. If the AI was seeing a 125 psi error then it would take only 5 psi to turn it on and perhaps never turn off depending which way the error was. Lots of variations.

 

[scubadada]

I'm not at all sure I understand the above posts. I've been diving a PPS transmitter for 10 years, 1460 dives. When I want to turn off the transmitter, I purge down to 0 psi and the transmitter is off. Of course, you must occasionally repurge the system once to remove residual pressure. This certainly does not require removing the reg, not replacing the 1st stage cover.... My AI pressure has never been incorrect, I dive a SPG backup. I don't think the pressure has anything to do with the last shutdown pressure...

 

[outofofficebrb]

Like @scubadada , I also dive an analog SPG while using AI. I used to have a Suunto which I used for about 85 dives then have used a Shearwater for almost 300 dives. I’ve never had the issues described. It’s always accurate and the pressure matches. I’ve had no problems. Maybe I’ve been lucky or @KWS has been unlucky. I’m not sure it matters, but I have an AL Legend LX and Legend octo.

@HKGuns congrats on your purchase. I love mine! I do still have an oceanic as a backup (serial vacation repetitive diver here).

 

[tursiops]

Of course, you must occasionally repurge the system once to remove residual pressure.

If you do not have a SPG mounted, there is usually no residual pressure to worry about. It comes from the pressure in the SPG hose taking a while to get out through the little hole in the end, back into the first stage. I think what happens is you turn off the gas, purge the 2nd stage, and the AI pressure goes to zero. But the transmitter does not turn off instantly, according to the specs it takes 4 mins at less than 50 psi for it to turn off. But there is no way to get 50 psi (over three ATM!) back into the system one the pressure is off. So it takes 4 mins, but it finally turns off. You can check this: turn it off. purge it, watch the AI (and SPG if you have one) go to zero. Wait a minute, turn it back on. The AI should still be there. But if you wait 5 mins, it should not.

 

[Glenn Williams]

I’m laughing out loud over how “Technical”:this thread has become. Really guys it’s pretty simple. Your wearing your Perdix AI. You turn off the regulator. You purge it. Look at your Perdix. What’s it reading? I bet it’s red and showing zero psi. If your on a boat it takes more than 4 minutes “usually” to get back to the dock. Look at your Perdix as your heading back. I bet within the time it originally said “0” psi, the transmitter has shut down before you reach the dock. Well at least mine does hahahahaha.

Glenn

 

[Jackie Treehorn]

I’m laughing out loud over how “Technical”:this thread has become.

Good point. And i'm pretty sure you called it on the first page that it would go like this.

People forget (or just don't care) that this is a basic scuba discussion subcategory.