scrane
Skin Diver
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First Name: William

New to double hose.

Tue Nov 05, 2019 5:36 pm

I have just completed the assembly of a DA Aquamaster with the Phoenix, HPR, DSV and second stage diaphragm from Bryan. I have set up the IP at 135, the second stage levereven with the bottom of the LP can, and everything holds steady under pressure. I took it to the pool yesterday. I set the position of the can very low on the VDH DH backplate. Between the shoulder blades as recommended. With my wing configuration the can is recessed about an inch back from the backplate plane. Because of the curve of my back I suspect the cans are 3 " from my back UW.

In the water the second stage is pressurized without demand. Nothing crazy, but it takes some effort and chipmunk cheeks to keep it contained. In horizontal trim it takes some sucking to initiate and maintain flow. More than I was expecting. Substantially more than required with a single hose reg.

Does all this seem normal? Should I try to bring the cans closer to my back? Does IP of 135 seem OK? Should I start fooling around with blocking the venturi ports? Or should I just get used to it?

I got into this more to approach fish easily more than to dive vintage or look cool. For me it will come down to the benefits of the remote exhaust vs ease of breathing and ease of use. I have been diving for quite a long time, but this is my first experience with a DH reg.

Any advice or encouragement will be much appreciated.

Sandy Crane
Boise, Idaho.

scrane
Skin Diver
Posts: 25
Joined: Sun Sep 15, 2019 10:07 am
First Name: William

Re: New to double hose.

Tue Nov 05, 2019 5:39 pm

I mean to say the second stage is pressurized without demand when I am vertical in the water

swimjim
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Re: New to double hose.

Tue Nov 05, 2019 7:09 pm

The IP set at 135 is spot on. If you are vertical in the water the cans are a little below the mouth piece. The means the ambient pressure in the mouth piece will be lower then the cans. That means that the reg will slightly free flow. If you are in a slightly heads up / normal diving position where the mouth piece is even with the cans, the reg will work properly as long as the horseshoe is adjusted properly. I suspect the horseshoe may be a touch high. Hope this makes sense..

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Herman
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Re: New to double hose.

Tue Nov 05, 2019 9:17 pm

Being slightly positive when vertical is normal. You can reduce it some by bringing the reg up a little closer to your head. Inches make a difference here.
The lever sounds a little low to me. First off, the reg MUST be pressurized when you set lever height. It will drop a good bit when you pressurize the reg so if you set it up unpressured, even if it's right, it won't be when you turn the air on. This is true for most regs. I pressurize the reg, adjust the lever to about even with the can lip, set the diaphragm on it and gently tap on it. I can gauge the spacing by feel, there should be a little play but not over 1/8 of an inch. An IP of 135 is fine but can be used as a tweaking adjustment for cracking pressure. Keep in mind, unlike a single hose reg, a DH is a balancing act of pressures, adjustments and positioning. When done correctly, you can get your PRAM to outperform most modern regs but it does require some tweaking and experimentation to get right, esp if you don't have any experience with DH regs.
Once you initiate airflow the venturi should be noticeable but not uncontrollable. If it's not , then start blocking one port partly, test and repeat until it's to your liking. The venturi is pretty effective so don't over do it.
One more possibility, is you BC. If you have any air in it and it's not snug on your body, it will float up from your back and make breathing difficult, again, inches here make a lot of difference. When horizontal, reach around your back and see if your fingers will go between your back the plate. If there is space, reduce your weight to remove the excess air and tighten up the harness.
Herman

scrane
Skin Diver
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Joined: Sun Sep 15, 2019 10:07 am
First Name: William

Re: New to double hose.

Wed Nov 06, 2019 11:09 am

Thank you swimjim and Herman.
I might have my harness set up to have the reg hang too low. I was at the pool and couldn't get a visual, but my finger tips of my no longer nimble arms would just touch the top of the reg when reaching back.
The lever was set up as you mentioned, Herman, even with the can lip. When I inhale slowly on dry land I can feel a very small dead space before the second stage is activated. I will crack the cans open and check the lever / diaphragm clearance.
On dry land the breathing is very easy and natural. No big rush. Underwater the drag on flow initiation and sustain is equal. Seems like some venturi boost is called for. I would increase the venturi except I am concerned it will also effect that positive pressure at vertical UW position?
Will lowering the IP to 125 have a negative effect? I am running an old SP108 with non adjustable orifice that would occasionally free flow upon hitting the water. Will lowering the IP help correct this? What is the acceptable range of IP?
I'm going to have to do some work on my BP/W. I think I can get rid of that 1" reg / BP offset without a problem. I will check the BP / me clearance as suggested.
I might be over reacting to my approaching this new old technology. I've become really spoiled by my modern Atomic reg that breathes easy and dry in all orientations.
Again, thanks.
Sandy.

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ScubaLawyer
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Re: New to double hose.

Wed Nov 06, 2019 11:49 am

You have received excellent advice from the guys that are in the know! All I can add (based on my 2 Phoenix/HPR outfitted regs) is that with a DSV I wouldn't be too concerned about cranking up the venturi. I have one side of the 2nd stage half blocked and the other side fully blocked and I love the flow delivery :)

I haven't dove (dived, diven?) my Atomic regs since last decade sometime as my Phoenix/HPR(s) breathe so effortlessly. Playing around and tweaking adjustments until it is perfect is half the fun. My 2psi.
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

scrane
Skin Diver
Posts: 25
Joined: Sun Sep 15, 2019 10:07 am
First Name: William

Re: New to double hose.

Fri Nov 08, 2019 9:38 am

Thanks, SL. Last night I took the Dremel to one of the old lever mounts and came up with an L shaped bracket that both holds the HPR in position and blocks a bleed hole. Now I need to get back to the pool to check things out.

scrane
Skin Diver
Posts: 25
Joined: Sun Sep 15, 2019 10:07 am
First Name: William

Re: New to double hose.

Thu Dec 12, 2019 10:02 am

Well, I finally got back into the pool with the Phoenix Aquamaster. After blocking one of the venturi holes and fiddling around with regulator position via the harness the regulator breathed much easier. Honestly, not up to what I have in my modern Legend second in horizontal trim. but pretty good.
I really had never thought much about exhaust bubbles in my standard single hose diving. But when I swapped out the double hose for the safe second after about 45 minutes of swimming I was surprised at the pummeling my face has been taking for all these years by the exhaust! :)
So, anyways, I'm tempted to half block the second venturi hole as ScubaLawyer mentioned as I experienced no downside from entirely blocking one hole.
In all I spent a relaxing hour and a half contentedly swimming in circles, contemplating the nature of the debris in the not so well maintained pool.

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SurfLung
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Re: New to double hose.

Thu Dec 12, 2019 1:14 pm

Nothing beats just getting in the water and swimming... Even in the winter when we have to settle for pool diving. Rich (50,001 Questions) and I are heading back to the high school pool this Sunday. This time, we're going to bring several Double Hose Regs and just keep swapping them out. Good chance to play with some of our less used regulators, AND I think its good for them to get some use. This time I'm bringing my "Made In France" DA AquaMaster... I haven't used that one very much since the original rebuild.
Image
P.S. This photo is from my re-subscribed PhotoBucket account!
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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