upgrading DA Aqua Master with new yoke

[cdharris]

I want to add a 3000+ psi yoke to my DA-AM, circa mid-60s. I know Conshelf's are the standard. I own both a USD Calypso IV and a Micra. I suppose neither will fit. Can anyone respond with certainty? Also, if they won't, is there a Conshelf model(s) that are preferred? If so, why? I'm looking to buy used, and cheaper is better. All the upgrades begin to add up.

Thanks.
-cdh

[SeaRat]

Are you going over 3000 psi? If so, probably a new yolk is prudent. But if not, the US Navy was using the DA Aquamaster on its 3000 psi AL tank systems. While some may argue the point, the DA Aquamaster will handle 3000 psi systems as is.

John

[cdharris]

John,

Thanks. I'm very pleased to have found a good information source for vintage gear. This is my 31st year of diving, and using a double hose will bring back memories of those early pool sessions. The only drawback was that the chlorine had just about done in those hoses. Wish I could lay my hands on that gear now.

My tank is routinely handled by a shop that overfills up to 3500, even 3700 without hot fills. If that tank should sit in a hot car in south Florida, well you get the picture. So yes, I'm worried about yoke deformation.

I realize that I could turn to a steel 72 (trying to head some folks off at the pass). In fact, I have one that failed inspection that is over 40 years old, and another that might pass, but since several shops I frequent in GA and FL won't fill it anyway, what's the sense? Also, in the Nashville area (my home) hydros are about twice the cost that they are in many other areas. Go figure. So I don't want to start a vintage tank collection for several reasons (just regulators).

Even without the 3000 psi consideration, won't I gain the benefits of a balanced reg? I see that as a good enough benefit alone, and what with the overfill issue, I figure why not? For those folks who respond "because, it ain't vintage", my response is: Why aren't you using punch cards rather than a keyboard?

Plus, I like tinkering with scuba gear so I wouldn't mind cracking open both regs and having at it. At the very least, I would like to educate myself either way. In fact, much of my interest is just that: curiosity.

So that brings me back to my original question: Calypso/Micra, yay or nay? (I suspect it is nay based on the body shape.) If nay, which Conshelf is best, or to be avoided?

- Clay

[SeaRat]

Clay,

First, if the shop is "routinely overfilling to 3500-3700 psig, I'd get another shop. Go to that shop, and tell them that you want the overpressure relief discs (copper) replaced on the tanks that were overfilled. They probably came close to rupturing. Also, if the tank does not pass hydro next time, it is probably because of these overfills. This LDS is incompetant when it comes to filling tanks. I'd also ask when the last time they checked the quality of the compressed air? There are others on this forum that are more up-to-date than I am on this, but when I was doing this a long-long time ago, we checked monthly (Oregon Department of Fish & Wildlife). If this LDS is ignorant of filling procedures, they may be ignorant of other things too.

Concerning the change of yolks, you need to change out the first stage too in order to get a balanced regulator first stage. The yolk will not make it a balanced regulator unless the first stage components in the nozzle are changed out. The Conshelf has the innards for this conversion (earlier models, I think), and there are entries here that explain how to do it.

John

[scubadiverbob]

Clay,

The local dive store (LDS is an abreviation used here) where I live will fill my tanks to what ever I want them filled to below 3000 psi. Anything above that, even though the new steel tanks will hold more, will wear out compressors faster. I'd paint "2,200 psi fills only" on the tanks. If they don't understand that, somethings wrong. A friend of mine has his tanks marked for lower fills cause he ads O2 for nitrox diving. He'd probably get upset if they over filled his tanks! John's right, you should look for another dive store. AL80's are mostly rated for 3,000psi (even with a + rating 3700 would be an overfill). Here in CA dive stores have to be cert. now to fill tanks. Do they have to be where you live?

Robert

[cdharris]

What does it take for a guy to get an answer around here? For some reason, this thread has turned into a discussion of how my tanks are filled. And there is some serious "conclusion jumping" going on as well. I'm perfectly happy with the overfills, and don't care if they shorten the life of my tank -- the more air the better. As much as I appreciate the sentiments, you fellas are treating me like some kind of ignorant newbie.

Let me point out, in fact, unshaded, stationary automobiles in central Florida commonly experience interior temperatures of l50ºF. Using the P-T law (P1T2 = P2T1; and yes, I converted to Kelvin), even at l35ºF, the tank pressure will rise from 3000 psi at 80ºF to 3300 psi. So, as long as my 3500 psi filled tank doesn't sit in the interior of a hot car, it shouldn't experience that much higher pressure than a 3000 psi filled tank that does. At least not enough that I'm going to worry about it. There may be some factors that I've overlooked, but again, I'm not going to lose sleep over it.

Whereas, I'm fossil diving on vacation and every minute longer I get to dive is another minute I'm having the time of my life, possibly picking up another million year old collectible that I value much more than my tank. And maybe finding "the one." Besides, the cost of a tank every five (or more like 10) years is nothing compared to the value and cost of the little vacation time I have, so I want every bit of bottom time I can get. With the overfill, and the shallow depth, I can get 140 minutes out of a tank on a good day. Let's see ANYONE do that with 66 (3000/80 at ~2400) to 72 cu ft.

So how about if some concerned, knowledgeable soul answers my original question (???please)? After extensive searching on the web, I still don't have a definite answer, and would like to end this thread knowing more than when it started.

Again, thanks.

[SeaRat]

Clay,

Probably the Calypso IV would work, but I don't think it was made for 3000 psig either. It, if I remember correctly, simply had the longer yolk. This was made originally to put a gauge adapter (banjo fitting) in that space between the regulator and valve. I think it has the same thread size and count, and approximately the same yolk width as the original. Dan shows a 3000 psi yolk which is adapted from a Dacor yolk which will fit a Royal Aquamaster (not sure about the DA Aquamaster), and you can see the size difference.

www.vintagescubasupply.com/access.html

The Micra looks like it comes off the Titan first stage, and that also looks like it might work. It would be a true 3000 psi yolk. But you'd have to try it to see. By the way, this involves removing the first stage high pressure nozzle an the DA Aquamaster, and that is best done with a special tool to hold the regulator's body (called a body wrench). You can probably make one out of wood to fit over the first stage parts, with a keyhole cutout. But I would not try to use a regular wrench, as that can mar the finish of the regulator.

I hear you about the dive time. However, if it were me, I'd be using twin 72s, where the placement of the Aquamaster is better on my back, to gain more dive time rather than overfilling the tanks. Twin steel 72s is 136 cubic feet of air, whereas your overfilled 80 is about 99 cubic feet of air. But you won't have all of that once you get in the water and the tank cools. And if one of those discs bursts in your trunk, you'll really know it. Also, while it is great that you are worried about the integrity of the yolk at 3500-3700 psig, I'm more than a little curious why you are not worried about the HP tank itself?

John

[scubadiverbob]

John,

I got a feeling they use different yokes. Would have to look it up in my USD manuals to be sure. I'm almost for certain the Dacor yokes have to be machined, then re-chromed, to fit. For what Dan charges it would be easier and less expensive to buy one from him than do all that is required to make one fit. I have a conshelf 6 and it has the long yoke. They are not a direct swap for the yoke on the DA, and also must be machined to fit (why I have valves on my 72's with HP ports).

Hope this helps. I'll try and find my USD manuals and see if the yokes have same part numbers later. (last time I had my manuals was when I overhauled my DA; they are around somewhere).

Robert

[SeaRat]

Clay,

I think I misread your post above; you are correct in that you probably are not over-taxing the tank at 3500 psig. But if it does get to ~150 degrees in a car, it can come close to 4000 psig (yes, I made the calculation too). The hydro people will fill it to ~5000 psig (5/3 of 3000 psig).

John

[duckbill]

So, what the guy needs is a 4000 psi yoke. LOL!
If you don't want to control your pressures, guy, you might want to get a balanced regulator

[SeaRat]

Duckbill,

I made the same mistake in reading what he said above. I think what he was saying is that by filling to 3500 psig, he was getting the some pressure in the tank as a tank filled to 3000 psig but left in the sun to heat up to 150 degrees. The numbers are close. My point was that if that 3500 psig fill was accidentally left in the sun, the final pressure would be just under 4000 psig at about 150 degrees F. But my reading of his post is that he would take measures to ensure this did not happen.

Clay,

I think this is what you were thinking above (my last post). Because I love the feel of the twins with a DA Aquamaster, I would still prefer the twin 72s in the situation you describe. But I think I understand where you were coming from.

John

[Deleted]

Clay

I had one of my 3000 psi alum 50's sit in the truck bed in south texas and bumped up to 3700 psi.......blew my hp seat on my Royal......was an old style rubber seat.......but the yoke was fine.......used the same reg in cozumel a year later, new teflon seat on an 80 alum........psi was 3400.......nothing happened with the yoke..........

But if you feel more comfortable with a high pressure yoke, and are not using a banjo for a spg......I have some 232 bar yokes for sale.....you would need to have the base hollowed out by a machinest or it might work as is........

Mossback

[sea.explorer]

Here is the deal with the yokes. No stock USD 3000psi yoke (including all conshelfs, Titan, SEA, Micra,Legend etc) will fit a DA AM or a RAM. If you have a Royal Aquamaster you can put a 3000psi yoke on it but it will need to be custom machined to have a step in it. The dimensions on the RAM first stage are different than the 1st stage of the DA. The RAM 1st stage sticks out farther than the DA allowing more room for the thicker/stronger yoke. You can buy a machined yoke for a RAM from Dan here:

www.vintagescubasupply.com/hoses.html

If you want a balanced reg you must put a RAM 1st stage in your DA. This would of coarse let you use a 3000psi yoke as well. The other advantage of the RAM 1st stage is that it can be used with a modern USD Teflon seat which is more dependable and rated to handle higher PSI. Just the RAM 1st stage is difficult to come by so you would probably be better off just buying a RAM. Which you can buy with all the upgrades you desire here:

www.vintagescubasupply.com/regs.html

-Ryan

[nemrod]

Like you said about the punch cards, you could just update to a Phoenix. Then add silicone hoses, duckbill, diaprham, cage mushroom valves with streamline cages and then use the new AL high pressure seat and then you will have a nitrox ready, 3,500 psi ready modern performance doublehose.

My PRAM:



Phoenix Voit:



The Phoenix is shark approved, 9 out of 10 sharks surveyed prefered the Phoenix to the old busted down and broke DA:



Nem

[cnotthoff]

if you haven't found a 3k rated yoke yet, give me a holler.

only way to get the 3k rated yoke off a calypso is with a hacksaw. when usd went to beefier yoke they integrated it with the body.

charlie