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Discussion of diving methods and equipment available prior to the development of BCDs beyond the horse collar. This forum is dedicated to the pre-1970 diving.
kombiguy
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An IP question on a DA AM

Mon Mar 02, 2015 8:10 pm

This probably should have gone in the technical section, but I can't post there, so here goes.

I, along with all the help from people here, have rebuilt my DA AM. Looks good, thanks to a Miami area chrome shop that rocks!

Put it on a tank, hooked up an IP gauge, and got it steady at 100 psi. What has me curious is the way it gets there.

I turn on the tank valve, and the reg pressurizes fine, with no leaks. But, when I depress the horseshoe lever, the IP gauge shows an immediate spike high, then drops into the 50 psi range. When I release the lever, the IP returns right to 110 psi and holds steady.

Is this normal?

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Bronze06
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Re: An IP question on a DA AM

Tue Mar 03, 2015 11:18 am

Hey,

Firstly, what was the pressure that you had in the tank when you did your IP check?
If it was at approx. 3000psi your IP gage should be reading about 110-115. If the tank was at 300-500 it should have read around 130-140psi.

To answer your question YES that does sound right if you are leaving the flow open from the lever for more that a second. On some IP gages you will see a pressure spike due to reverse shock wave in the line as pressure is suddenly released, then you will see a uniform fall of pressure from outflow of gas. Of course when you activate the horseshoe lever when pressurized with an IP gage attached and let it free flow for about a second or two you should see a drop of about 30-50 psi., with an fairly immediate return to the original starting IP setting. If this isn't happening follow the guidelines below. I hope the following helps.

Here is the rule for IP set on unbalanced 2 stage regs straight from Bryan's VDH archive:

"Setting the IP on an unbalanced 1st stage can be accomplished in two ways. You can follow the factory recommended procedures outlined in the service manual or use the method below which has been used for many years. Both will give good results with a slight edge in performance going to the method described below.
First you will need a cylinder with 300 psi of air in it. Why so low you might ask? On an unbalanced regulator the intermediate pressure is at its HIGHEST when the cylinder pressure is LOWEST.
There are several posts in the technical section on the mechanics of this and can be found using the search function of the forum. Another great source for all things regulator related is the book Regulator Savvy available at Scuba Tools.com
Secure the cylinder in a horizontal position on your workbench or table. Be sure to have it supported on both sides so it cannot roll off. Insure that the cylinder you are working with has at least 300psi of air and no more than 500 psi. Next attach your assembled regulator to the cylinder and slowly open the valve.
Using a 3/8” hex head wrench, slowly turn the adjustment nut clockwise until you hear a slight hiss of air passing through the 2nd stage. When you hear it stop turning the nut and slowly turn it counter clockwise 1/8th of a turn.
Stop for a moment and cycle air through the 2nd stage a few times by lifting and releasing the 2nd stage nut . Then put the hex wrench back in the nut and slowly turn it clockwise again till a hiss is heard and once again reverse directions by 1/8th of a turn.
Finally turn the air off and lift the 2nd stage nut a few times to bleed off all the air in the regulator. Then turn the air back on and check adjust the IP using the procedure above one final time. When you are sure you have the adjustments correct allow the regulator to set under pressure for 5-10 minutes. If there is no leak during this time your regulator IP is set and you are ready for final assembly. If you are hearing a leak during this time this indicates that your high pressure seat is not seated correctly and needs further attention.
Lastly check the IP with a gauge making sure it is stable and in a range of 130 to 145 psi
"

Is the above procedure the one you followed for the 2nd stage?

AS far as IP from the 1st Stage is concerned

If you used just a 3000 psi tank and did your IP set, you might be over pressurizing the reg. At a low pressure (300psi) the IP should be running at approx., 135 psi +/- 5. I use the two tank method, one tank at 3000psi and the other at 300-500psi. I use that Hookah port with an adapter and run my IP gage off that. I check the reg on the 3000psi tank and adjust it for 110psi then I place the reg on the 300 psi tank and check it there. It should read on or about 135. I do this three to four times tweaking a little each time. I then let it sit for a day or two under pressure for set and then re-check IP and adjust as needed.


Trouble shooting: You might either have overpressure situation at low "Tank" pressure (300-500psi), meaning that you need to adjust the adjustment nut and get your IP gage up to 130-140psi IF THE TANK IS AT 300-500psi.!!! OR you might have an UNDERPRESURE situation at high "Tank" pressure (2800-3000psi), meaning you need to adjust your IP at that pressure to 110-115 psi.
"Where'd ya get that ol' thang, don't cha' know them thare things ill kill ya!"

Live From the Red Sea,

Russ

kombiguy
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Re: An IP question on a DA AM

Tue Mar 03, 2015 2:27 pm

Thanks! It was that high pressure spike that had me concerned.

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Herman
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Re: An IP question on a DA AM

Tue Mar 03, 2015 3:11 pm

I am going to have to disagree with Russ. A pressure drop of somewhere in the 10-15 psi range at full flow is normal but down to 50 from 100 is way more than is normal. At that amount, there is some restriction in the flow path, either a partly closed tank valve, a clogged dip tube in tank, a J valve in "dive" mode or a badly clogged filter. As for the pressure spike, it is fairly common for the IP to overshoot a little on the initial pressurization but it should not continue to do so as you depress the lever.
Herman

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Bronze06
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Re: An IP question on a DA AM

Tue Mar 03, 2015 3:26 pm

Hey Herman,

I guess I'm referring to a long or prolonged free flow that bottoms out and doesn't allow the reg time to back fill and this is all volume and pressure dictated. I got that understanding from kombiguy's description. I am in agreement with you that the normal test breath for that matter should not cause the IP to drop so radically, though there are some regs that, as you know, do have large pressure swings. But if you stomp on that lever you will see large psi fall. If all things being equal and Kombi has done the full rebuild as per informational guidance, you are right again in that it must be a tank obstruction. I wish I was there to see it myself.

Kombiguy, listen to Herman on this stuff, he has been doing the DH rebuild a hell of a lot longer than I have. Also, were you breathing the reg or stomping down on the 2nd stage lever with your hand like you would to clear a single hose?
"Where'd ya get that ol' thang, don't cha' know them thare things ill kill ya!"

Live From the Red Sea,

Russ

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Herman
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Re: An IP question on a DA AM

Tue Mar 03, 2015 5:07 pm

Ya know, to be honest, I have never held one down fully....the cheap skate in me just can't stand to waste the air. :)
But to your point, the second stage is capable of flowing a LOT more air than anyone can possibly breath so held fully open it may well drop down more but there is no reason to do so since that way surpasses the volume anyone can inhale. I am referring to deep, heavy inhales....more than normal but still within the easy realm of a diver working hard.

I know this warning has been posted many times but since there may be new people following this thread NEVER INHALE DIRECTLY FROM THE FEED HORN,ALWAYS HAVE A COMPLETE HOSE LOOP CONNECTED TO THE REG. The venturi on these regs can be quite strong, esp if you have installed an HPR. If you inhale off the horn directly and the venturi goes full bore it can very rapidly cause serious lung damage. Don't do it.
Herman

kombiguy
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Re: An IP question on a DA AM

Tue Mar 03, 2015 5:24 pm

I finished it up today. The drop in IP when operating the horseshoe is now only 15-20 psi. The initial spike in pressure is gone. The ip is stable; on a 300 psi tank it holds steady at 130, on a full 3000psi tank, right at 110 and steady.

I just installed a duckbill eliminator, so I have to wait 48 hours to dive it.

Thanks for all the help so far, it looks like I'm getting near the end!

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Bronze06
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Re: An IP question on a DA AM

Wed Mar 04, 2015 3:59 pm

Sounds like you are ready to go Kombiguy. Are you going to test it in a pool or shallow water body dive first?
And yes Herman I know we are not supposed to breath directly from the horns and yes I admit it, during the frenzy of rebuild and testing I have done that. As far as stomping on the reg, I am lucky here as we have a Bauer right here on site, so I guess I am getting into wasteful air habits. The up side is I have all the air I need for testing and rebuild. :D

Have Fun Out There
"Where'd ya get that ol' thang, don't cha' know them thare things ill kill ya!"

Live From the Red Sea,

Russ

kombiguy
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Re: An IP question on a DA AM

Thu Mar 05, 2015 4:47 pm

Yep! Tomorrow am in my pool first, then in the shallow waters of Blue Heron Bridge in Riviera Beach, FL. Then, wherever I feel like it! :D

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Bronze06
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Re: An IP question on a DA AM

Thu Mar 19, 2015 4:58 am

So How Did It Go!!???? :?:
"Where'd ya get that ol' thang, don't cha' know them thare things ill kill ya!"

Live From the Red Sea,

Russ

kombiguy
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Re: An IP question on a DA AM

Tue Jul 07, 2015 2:59 pm

After four long months off, I got it in the pool today.

Breathed poorly, started to pull it apart to see what's what. The first stage side of the body was full of water. Well, not literally full, but 1/4 full.

Am I correct in assuming this isn't the way it's supposed to be?

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Creed
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Re: An IP question on a DA AM

Tue Jul 07, 2015 5:31 pm

Breathed poorly, started to pull it apart to see what's what. The first stage side of the body was full of water. Well, not literally full, but 1/4 full.

Am I correct in assuming this isn't the way it's supposed to be?
Correct. It could be leaking in one (or more) of three things:
1) Inhalation hose - especially check the ends for cuts
2) Diaphragm - could be a tear or hole or it could leak around the edge if it were folded or kinked in some way when putting the cans together(I've seen old, flattened diaphragms that didn't want to lay down flat)
3) Body-can connection(past the rubber body ring) - check that the body ring was tightened down and that there are no tears visible

That's what I would check first. Aside from that, the only other thing I can think of is a cracked can.
"Haul the sheet in as we ride on the wind that our
forefathers harnessed before us
Hear the bells ring as the tide rigging sings.
It's a son of a gun of a chorus" - Jimmy Buffet

swimjim
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Re: An IP question on a DA AM

Tue Jul 07, 2015 6:44 pm

Could also be bad mouth piece valves or a compromised body gasket. Body gasket unlikely though.

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Herman
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Re: An IP question on a DA AM

Wed Jul 08, 2015 8:29 am

Is the body gasket on the correct side?? I have seen more than one on the wrong side. It should be between the cans and the body(IOW outside of the cans), not between the cans and the body ring (inside). To hunt down the leak, remove the supply hose, put a dust cap on or attach the reg to a tank (WITH THE VALVE CLOSED!!)or just hold your finger over the filter and gently inhale, the main diaphragm should pull in but then you should not get any more air flow. If you have a leak in the main cans, you will feel and/or hear it.
Herman

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