DA Aqua master

[swimjim]

Some time ago I acquired a DA Aqua master and I had Dan rebuild it last fall. I finally got a chance to use it yesterday down at Haigh quarry in Kankakee ill. I was testing my new doubles rig and on the second dive after I had the psi down to 2200 I put the DA on. I used my Poseidon Xstreams to the bottom, about 50 feet. I got my buoyancy under control and made the switch. I cleared the regulator and continued the dive. Dan did an awesome job(rebuilding) tuning this reg up. Smooth as silk. I was really impressed. I used the DA for about twenty minutes and didn't want to finish the dive. Alas, the 35 degree water was starting to get to me a bit. I have a Dacor Diving Lung of about the same vintage and the DA is light years ahead of it. I just want to say, awesome job Dan, the reg is working Great! I can't wait to try my DA "NAVY" approved.

Jim

[nemrod]

One of the local scuba shops was in the water at the Y pool. They were doing their instant diver PadI class and I was swimming my laps and working in the fin testing a few weeks back. I also had my superb DA, the one that is occasionally for sale, so after chatting with my scuba Dive Master friend for a minute and listening to him tell the students how hard double hose regs were to breath from I slapped it on his tank and put him in the water. The look on his face when he realized it breathed as well as his super duper plastic POC was quite impressive to me.

There is the slight lag on inhalation and the somewhat higher cracking effort but the WOB cycle total work is just not that much different. It is that lag and that cracking effort that makes me want a servo valve assist but let's not go there again.

I just rebuilt my RAM number three over the last week and got it in the pool today for testing and tweaking. IP is set to 135psi at 2500 psi tank pressure. I used rebuild parts mostly from vintagedoublehose.com and a new set of silicone cage valves from vintagescubasupply.com and I had a new NOS duckbill so I installed that. I did my secret mod and I installed a new blue Conshelf seat from Bryan and I polished the the high pressure button and push pin button and greased them lightly with pure silicone grease. The result is a regulator that breaths superior to most any modern plastic rig.
Nemrod

[treasureman]

ok whats the secret mod ? inquiring minds want to know... please tell...

also why grease the hp button and pin. I found one of the DAAM with a ton of grease under the HP button, couldnt figure out why, as it is not a part that moves very much. Also is grease safe to use in this area?

[Captain]

If Nemrod told you the secret mod he would have to kill you.

[JES]

captain said:

If Nemrod told you the secret mod he would have to kill you.

[nemrod]

The silicone I use is the paste type that comes in the little jars. It is pure and very thick. I use just a film of it on moving parts. Careful about O-rings, it can make them not want to stay put.

When it comes to O-rings, you can put a tiny amount on your fingers and then work it into the O-ring by rubbing it between your fingers and then gently wiping off so as not to leave any excess. Excessive lubrication will result in O-rings that extrude.

Yes, the HP diaphram does move and often the rubber welds/sticks to the buttons causing a decided resistence which causes a noticeable breathing lag. At least that is what I think. Lot's of grease squirted all in there is just going to gunk up the works. The buttons I am talking of are the one under the spring and the one that pushes the HP seat push pin.

Secret mod---hmmmm--nah--I would have to kill you.

SwimJim, sounds like you have a great performer, cannot wait to hear how your Navy does after Dan is done with it.

Nemrod

[treasureman]

I will face the danger alone if I must... If i understand, the flat button that the HP spring is under is the one with the grease. What about the other side of the diaphragm. whre the mushroom shaped button pushes the hp pin up into the nozzle. does it get da grease as well. This of course is a light dusting??

[treasureman]

If you tell me the secret mod, I will tell you the secret of success to a long lasting marriage.

Of course i only learned this after i got divorced. But it does work. this is serious advice and has been proven to work by those that follow it.

[nemrod]

Treasureman, I have been married for 27 years to the same person. I met her in a geology lab and knew on the spot she was the one--thanks for the offer of advice.

I should never have used the word grease! On some Royals, the diaphram is fabric faced and laminated--the side against the spring. The rebuild kit diaphrams are all rubber. They enjoy a silicone rub down and then wipe it off clean. There are two buttons, the one under the heavy spring and internally the one that pushes the pin that offseats the HP seat. For whatever reason both of those buttons often become stuck to the rubber diaphram. I polish them clean and smooth until they shine like a mirrior. I then super lightly, barely, put a film of silicone grease on the face so as to prevent them from sticking again to the rubber diaphram, the polishing helps in that regard also. It is a small thing but it does help--in a small way.

The secret mods, lol, I was mostly just seeing if I had y'alls attention, I used to teach high school science, I was just wonderingif anyone read this stuff. Bonus points you know-just teasing.

The push pin dimension and the diameter of the volcano orifice varies on these regulators. Ever wonder why one breaths better than another and yet they are "identical". Well, whether as a result of ham fisted shop techs or low quality control at USD, many of these regulators are not per specification. Luis, in his various articals measured this stuff and noted a similar thing and he even published a pin dimension. I had been measuring such things also in an attempt to make all three of my RAMs breath the same. Essentially, to use an engine term, I am "blue printing" my RAMs to al be the same. Bryan has push pins that come with the new silicone seats. These can be custom trimmed. The orfice can be set to factory dimension. I recommend that 99.9% of persons should not approach their regulator with any sort of drill and reamer.
It was simply the result of measuring regulators to determine why they behave differently. You can play with push pins, they are sorta expendable--I recommend not reaming the volcano orifice but I have done that to make them uniform. obviously--one tiny, tiny, slip and a perfectly good part is RUINED. I recommend not performing this secret mod as the benifit is vastly countered by the downside--a ruined regulator. But y'all twisted my arm.
Nemrod

[nemrod]

Let me say something, don't get out any drills, please, I don't want ebay flooded with ruined RAMs. I work occasionally on turbine engines and jet aircraft where a single slip costs the boss a quarter million easy or least the price of a Lexus. I am no super mechanic but I have developed the ability to finesse certain types of things. One of them is the ability to make perfectly smooth, prefectly round, perfectly on size holes, tapers and all that. So it is not intended as an insult when I tell most people not to attempt this secret mod.
Nemrod

[luis]

Hi James

Please keep in mind that (in the Royal Aqua Master) the diameter of the volcano orifice needs to match the diameter of the cylindrical stem on the back side of the seat in other for the first stage to be balanced. The cylindrical stem fits into the O-ring in the spring block. That spring block is actually the low pressure balancing chamber (LP air is fed into it via the small hole in the center of the seat).

If you enlarge the volcano orifice the balance will be offset (granted to a small degree).

I believe the inside diameter of the volcano orifice is approximately 0.121 inches.

I am sure you only altered the ID within the acceptable tolerances, but I am pointing this out for everyone’s benefit.

The bottom line for a good first stage is that it provides a relatively constant intermediate pressure at any flow rate and at any tank pressure. The IP variation on the Royals that I have seen is less than 8 psi (maybe 10 psi under extreme flow rates).


The volcano orifices with all kinds of different dimensions were for the DA Aqua Master’s. In the case of a non-balanced 1st stage the smaller the orifice the less the IP is affected by changing tank pressure, but the higher the flow drag. Therefore, how big USD made the size of the orifice was always a compromise, between flow rate and a change in intermediate pressure (as a function of tank pressure). I don’t know why they made changes or how they arrived at any decisions.

[duckbill]

luis said:

Please keep in mind that (in the Royal Aqua Master) the diameter of the volcano orifice needs to match the diameter of the cylindrical stem on the back side of the seat in other for the first stage to be balanced.

Excellent point, Luis. Not to be nit picky, but FWIW I believe it is actually the FREE AREA of the volcano orifice (i.e. the area of the orifice less the cross sectional area of the pin) which must equal the cross sectional area of the seat stem, no? So, the orifice diameter will correctly be slightly larger than that of the seat stem.

[duckbill]

As you were.
Actually, come to think of it, the critical measurement to be subtracted from the area of the orifice is the area of the pin where it contacts the seat, which, since they are usually rounded down to a fine tip, would be much smaller than the sectional area of the pin itself.
The diameter of the orifice WOULD still be slightly larger than that of the seat stem, but probably by such a small amount as to be nonsignificant.
Carry on.

[nemrod]

Rather more than thinking in terms of larger or smaller I am thinking in terms of more uniform and consistent in shape and cross sectional area.

This is not the only place I have found small variances. All five RAMs I have owned had slightly different pin lengths as well as did another square lablel I rebuilt and sold. All in all between five RAMs I have found three different pin lengths. If nozzle assemblies were a dime a dozen I think there are a few other areas I might consider messing with. This is my thinking, that is why it was a secret mod--lol.

I currently have three RAMs, one of which breathed partcularly well when I got it despite it having sat for close to three decades in some fellows sock drawer--yep. I could not get my other two or the two I sold to equal it. I swapped diaphrams and made measurements and still it breathed better. It was only after I began looking at very tiny things did I come to realize--that was the difference---or so I think. Now all three breath very close to the same, though the sock drawer one still does a tad better. Perhaps because it was essentially new and the last of the line it was the only one that had original factory parts as assmebled from the factory. The others I am sure had been rebuilt or at least opened up.

When I bought this DA I have, it came with a sack of RAM parts--duh--no wonder it was incorrectly assembled with the RAM parts substituted. Measuring the various new NOS stock springs, reproduction springs etc and other such things I started picking through them to get the ones that were most nearly the same. Perhaps it is overkill, a search for the Holy Grail, I just wanted them to perform and breath the same.

I think there is more room for improvement but it may lie in something like a thinner, lighter and more responsive main diaphram, thin and super flexible silicone cage valves etc.

The best secret mod is simple, careful attention to assemby, cleaning and lubrication following the manual.

Perhaps after I get the new nozzle from Luis I will take one of my remaining nozzles and play around a bit more.

Nemrod

[Broxton Carol]

I had wrote about adjusting the pin length a year ago. The height of the support is critical if you want a real efficiant reg. They all breathe good, but if you take out your nozzle, and look at the height of the support from the face of the nozzle, the support that is a tad higher off contact with the nozzle will really let the air in. If you Have found that the height is determined by WEAR in the base of the seat itself, from a lot of use. Sometimes just switching to a new seat will bring it right into tolerance. I have found some supports that were a tad off too. So swap around what you got. Dont go drilling holes, opening nozzles, or stuff like that. The inventor likely did all that stuff. So as it says in the 1917 Curtiss aircraft manual " Avoid that dangerous habit. TINKERITUS. When the engine is running smoothly, LEAVE IT ALONE" ! Now go back to sleep