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Bubblehead628
Skin Diver
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First Name: Doug
Location: Ormond Beach, Fl

IP adjustment

Mon Feb 18, 2019 6:24 pm

I checked the IP on my DA Aquamaster (phoenix/HPR) and it's reading 120. How do I adjust it? I tried searching this forum and have not found a how to on this.

Thanks

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tripplec
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First Name: Chris
Location: Coos Bay Oregon
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Re: IP adjustment

Mon Feb 18, 2019 10:26 pm

Bryan has some verry good youtube videos on doing that stuff. It is the same procedure as the normal daam if you vissit the downloads section and grab the service manual.

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Herman
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Re: IP adjustment

Tue Feb 19, 2019 8:25 am

If it's breathing OK and the IP is stable, there is no good reason to change it, 120 is OK. It is not uncommon for the IP to drift some over long periods (weeks/months- not minutes ) as rubber components take a set. This is not a problem, you can reset it if you want but unless there is a marked difference in breathing performance, it's not a big deal.....and not worth it IMO if you have to remove/install C clips.

That said, it's easy to change, Open the cans and locate the 3/8 hex hole in the center. While monitoring the IP , turn the hex clockwise to increase the IP. make a small adjustment then vent some air by depressing the second stage a couple times to ensure the IP rebounds to it's last setting, adjust again as needed. It is common for the IP to return to a little lower amount than the initial amount it stopped at when you adjusted the hex. It should return the same value each time you vent the second stage after the initial vent, repeat as needed until you get the desired IP. For example, you adjust the IP to 135 then operate the second stage, it drops then rebounds to 130, you vent it again and it returns to 130. That is normal.
The exact IP is not critical, it just needs to remain at whatever it is at , no creeping or wondering around and when the second stage is operated, it should rebound to the same value.
Herman

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tripplec
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Re: IP adjustment

Tue Feb 19, 2019 9:16 am

Please corect me if I've heard wrong, but does higher IP such as 135-145 make single hose octos more susceptible to icing? Ive heard of dive shops "detuning" regs when people were having a problem.

Sent from my SAMSUNG-SM-J320A using Tapatalk


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Bubblehead628
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Joined: Thu Feb 14, 2013 11:33 am
First Name: Doug
Location: Ormond Beach, Fl

Re: IP adjustment

Tue Feb 19, 2019 4:13 pm

Thank you guys for the help, I really appreciate it.

swimjim
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Location: Belgium WI

Re: IP adjustment

Tue Feb 19, 2019 7:49 pm

tripplec wrote:
Tue Feb 19, 2019 9:16 am
Please corect me if I've heard wrong, but does higher IP such as 135-145 make single hose octos more susceptible to icing? Ive heard of dive shops "detuning" regs when people were having a problem.

Sent from my SAMSUNG-SM-J320A using Tapatalk
Most of the regs that I have worked on, the recommended IP is between 135 - 142. Sounds like another dive shop fairy tale to me. In my somewhat limited experience working on my personal stuff.... US Divers, Scuba Pro, Dacor, HOG, Sherwood, etc... Second stages in "normal" diving conditions don't have an issue until you get North of 150 psi for an IP. I usually set my IP's around 140.
Generally second stages don't have an issue as long as they are being fed a proper IP. If the first stage starts to freeze up and starts delivering air to the second at 300 psi, bad things happen.
Maintain your regs, that is, service them at a reasonable interval . Do not breath off your regs at the surface when ice diving. Don't fill your AL80 to 5000 psi and expect your reg that is rated to 3442 psi to work properly and you'll be fine.

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antique diver
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Re: IP adjustment

Wed Feb 20, 2019 9:18 am

Seems like I remember a recommendation or bulletin from US Divers about lowering the IP for lower water temperatures. That would have been a long time ago (1970's or 80's), and I don't remember the numbers given. I'll look for that and let you know if I find the details.
The older I get the better I was.

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tripplec
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Re: IP adjustment

Wed Feb 20, 2019 10:32 am

antique diver, you should write a book on your knowledge of survice bulletins and tipsntricks. Put it in the buy and sell section. It would sit nicely next to all our Regulator Savvy books.

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antique diver
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Re: IP adjustment

Wed Feb 20, 2019 11:28 am

tripplec wrote:
Wed Feb 20, 2019 10:32 am
antique diver, you should write a book on your knowledge of survice bulletins and tipsntricks. Put it in the buy and sell section. It would sit nicely next to all our Regulator Savvy books.

Sent from my SAMSUNG-SM-J320A using Tapatalk
Thanks for the vote of confidence. :) I just wish I could remember all the details of stuff that I have vague recall of.

I'll try to find that bulletin on the cold water settings, but some of my old manuals and papers got scattered or lost.
The older I get the better I was.

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luis
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Re: IP adjustment

Wed Feb 20, 2019 1:24 pm

When the recommendation to lower the IP came out, most second stages were basic down-stream demand valves. Lowering the IP (without adjusting anything else) is an easy way to detune a regulator, specially an unbalanced down-stream second stage.

Detuning a regulator just a little makes it a bit harder to breathe, which also makes it a bit less likely to free-flow. This is particularly important with an octopus when you first slip into icy-cold water. If you induce a free-flow in that condition, you are not stopping it.

Lowering the IP is not as effective with a pneumatically balanced second stage, but it doesn’t hurt and it could help a little.
Luis

Buceador con escafandra autónoma clásica.

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antique diver
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Location: North-Central Texas

Re: IP adjustment

Wed Feb 20, 2019 5:33 pm

The differential between the IP and ambient pressures affects the potential cooling effect of the expanding gas. The greater the expansion the greater the adiabatic cooling. Realistically it's probably not much in this case, but every little bit adds up.

You have probably seen the rapid release of air from a tank valve produce icing on the valve, even in the summer.
The older I get the better I was.

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