A couple of Aqua Master questions.

[elmer fudd]

I won an E-bay auction the other day that I didn't expect to and today I received a round label DA Aqua Master.

It was pretty dirty, so I washed it up and damned if it didn't come out looking surprisingly good. Next I put it on a tank and took a few breaths out of it. It inhaled nice, but exhaling was very difficult. I opened it up at this point and discovered the duck bill had bonded to itself and the inside of the reg. Fortunately I had a spare.

Now one thing I noticed while I was inside it was that the can with the label on it had the holes cut in it for a square label's tabs. Interesting. I opened up my RAM, (different reg), to see if it was the same, but it didn't have the same holes.

Now I'm wondering if perhaps this might have been a slightly earlier reg that had the square label replaced with a round one in an attempt to make it look more modern.

It's a shiny chrome reg, serial #109802, with the tire knob on the yoke.



My other question is completely unrelated, but one thing I have always heard is that you don't want to run the old regs at too high of a pressure because it's hard on the seats. But what about with a balanced regulator? Seems to me that with a balanced regulator the pressure on the seats should be the same regardless of the pressure in the tank. It may be done to normalize the work of breathing, but it seems to me that an added benefit would be that it would also eliminate many of the problems associated with high pressure tanks.

 

[halocline]

It's possible someone put a reproduction round label on the can. The rectangular label cans have an indentation for the label that's easy to see. If your aquamaster has one, you can get a very nice reproduction DA label from a guy named Jerry that does them for vintage double hose. In fact, the label on your RAM is one of his.

Regarding the seat, the idea of extra wear on an unbalanced HP seat at high tank pressures is greatly exaggerated IMO. Sure, there's more upstream pressure pushing the seat against the orifice. But, the IP lowers in response to that increase; meaning that the seating force of the seat against the orifice is the same. The only thing this does not take into consideration is any increase in seating force necessary to maintain a seal against a higher pressure gradient. That consideration would be exactly the same for both balanced and unbalanced regulators. If the reg is not creeping (meaning IP is stable, in the normal range) then I don't see how there is any greater seating force and hence any greater wear on the seat.

The main issue with higher pressure tanks and the DA nozzle (in my experience) has to do with the lower quality seal of the seat material itself. I just don't think it holds a seal as well as the RAM seat. This is aggravated at higher tank pressures because the pressure gradient across the seat is higher, and mine used to creep worse above 2500 PSI. The other, more commonly referred to issue is the fact that higher tank pressure means lower IP and consequently harder breathing. That one I found to be a significant disadvantage with the DA.

If you enjoy diving with the DA and get can get a good stable IP, you can experiment with the differences in performance between the DA and RAM nozzles, which I always found interesting. For me though, pretty soon I got tired of dealing with the creepy seats (I hate IP creep..) so when a phoenix nozzle became available, I went for it and never regretted spending the money.

 

[John C. Ratliff]

The DA Aquamaster was used by the US Navy at 3000 psig for many years. When we were taught how to maintain them, we used them at 3000 psig without problems. The main concern, expressed by many here, is not the seat but the yolk, which was more deformable in the DA Aquamaster than in later RAM models. But I have not seen that problem.

Be cautious about setting the IP on the DA Aquamaster (unbalanced), as it must be set at about 500 psig. If it is set high at a higher tank pressure, because the IP does go up an the tank pressure goes down, it may free flow at the lower pressures. I think this is the "IP creep" that Mattboy is talking about above.

Upgrading to the Phoenix nozzle will give you the advantage of a balanced regulator (the Mossback Mk III does the same), plus both LP and HP ports.

SeaRat

 

[elmer fudd]

It's possible someone put a reproduction round label on the can. The rectangular label cans have an indentation for the label that's easy to see. If your aquamaster has one, you can get a very nice reproduction DA label from a guy named Jerry that does them for vintage double hose. In fact, the label on your RAM is one of his.

It does indeed have the rectangular indentation. Now whether it was originally a square label and someone decided to "upgrade" to a round label or whether AquaLung just had a bunch of old stock cans and decided to go ahead and use them anyway with the new label would be the question.

 

[Nemrod]

Some old cans were re-pressed, I have seen it before.

VDH forum is the place to go for "how to" as well exists all of the documentation.

The DA seat is not the same as the RAM seat. While the DA seat (vdh has new ones) can handle the 3,000 psi the newer version does better and the RAM could care less with a Titan HP seat installed.

The DA is an unbalanced design, the IP drifts naturally as the tank pressure decreases, you need to follow the manual on set up for these, setting IP to 125 psi at about tank pressure 250 psi I think it is, I don't have my manual in front of me now. IP rises as tank pressure falls with the unbalanced DA. At 3,000 psi the DA will breath perhaps a bit stiff. The RAM is a balanced design and IP remains the same throughout the dive until tank pressure drops below the IP, typically about 135 psi for most of us who tune the RAM.

N

 

[duckbill]

Sure, there's more upstream pressure pushing the seat against the orifice. But, the IP lowers in response to that increase; meaning that the seating force of the seat against the orifice is the same.

Mr. Fudd, it is possible that someone stuck a round label on a square label can. On the other hand, as Nemrod said many of the last square label cans were used as round label regs by USD. Also as Nemrod said, the can was still stamped with a circular recess for the round label on those. If your top box has the serial number stamped on the back (i.e. under the chrome), then it was originally a round labeled DAAM, and your top box is probably original as it is. Is the bottom box recessed for the round label?

BTW, the serrations on a plastic knife are wonderful at helping to remove duckbill material that is stuck in the can, and won't harm the chrome.

 

[Nemrod]

True, good point Duckbill, round label DA and RAM should have the serial number on the can, the top box, if so it was originally produced as a round label.

The top box, BTW, is the one with the first and second stage body assembly and yoke, the bottom box is the one with the duckbill and label.

N

 

[elmer fudd]

That's pretty conclusive. It does have the serial number on the back and the circular indentation. So round label it is.

Seems kind of strange that they would continue to stamp the cans with a place for the square label. Just a guess, but I'm thinking this particular regulator was probably made in 1970, not long after the switch.

 

[elmer fudd]

I'm thinking I'll set this one up as a PRAM for day to day diving. I got a good price on it, ($99). It was one of those E-bay auctions that you enter a low-ball price early on and fully expect to be outbid on 2 days before the auction ends, then when it ends you think, "geez, I won. How did that happen? Now I have to pay for it and explain it to the wife". Turns out it was in impressive condition, just very dirty. It looks like it was only used a dozen times or so and then got hung up in some guys garage back in 1975 and forgotten. It had a patina of grime on it and a dead spider in the mouthpiece. After about an hour of scrubbing at it with a toothbrush however it came out looking nice.