Need advice on what to do with my DA Aquamaster

[Six2Life]

About a year ago I traded for a DA Aquamaster with the hopes of giving DH diving a try. When I received it, it had a bit of corrosion but nothing extreme and externally the hoses and mouthpiece looked to be in decent shape. Since I wasn't exactly sure if I'd like diving the DH's I just wanted to get the reg diving with the minimum expense to see if it was for me or not. After tearing it down my list of needed parts consisted of new mouthpiece valves, a duckbill, band clamp, hookah port adapter to connect my ip guage, and a few gaskets for the cans and nozzle which I bought from VDH. The one crappy thing I discovered after pulling the nozzle apart is that there was a spot of corrosion right on the knife edge of the volcano orifice. After looking into several options for addressing this I decided to buy one of herman's tools for reconditioning the knife edge. After using the tool the orifice looks much better. Lockup is a tad mushy at 135psi with about another 5psi of creep over a couple minutes with a tank at about 300psi. With tank at 2500 ip is about 105. I've had it in the water a few times and the performance seemed to be ok but I never got really comfortable with it. I definitely felt like i needed to maintain a slightly head-up position to keep it breathing ok. I did try to position the can in between my shoulder blades. Oh, and it does have the original diaphragm which, while intact, did seem a little stiff to me. All of this is from last summer and I haven't really messed with it much since then.

So now that diving weather is here again I'd like to give this thing another try but would prefer that it worked a little better than it did the last time I had it out. I'm just trying to decide which improvements would be the best bang for the buck. I'm not to the point where I want to just replace everything and Phoenix it out, but just get it working well enough so I can play around with it once in awhile. Would I get the biggest benefit from updating the second stage with an HPR and silicone diaphragm, or would I be better off replacing the nozzle or possible putting in a RAM nozzle? The ip seems stable enough that it shouldn't be causing problems but I'm not really familiar with the performance limitations of these unbalanced first stages.

Or maybe I just need some lessons on how to dive a doublehose correctly?

 

[Luis H]

The new HPR and a new silicone diaphragm will give you a huge boost in performance and it is a very economical upgrade. You will still notice that the breathing get a bit easier as the tank pressure drop, but you will notice an improvements at all tank pressures.

The RAM nozzle is not only balanced, but it also has larger air flow passages than a DA. The difference is not only noticed with a full tank, but it can also be noticed very deep or working hard. If you are not doing deep dives or working hard I would put off the RAM upgrade for a while and eventually get a Phoenix.

The Phoenix works very similar to the RAM, but it also has a bit improved air passages and it obviously gives you the HP and LP ports. It also has a replaceable volcano, so you never have the issue again of having a compromised volcano orifice.

Again, if I was going to limit the improvements, the HPR with a new silicone diaphragm will give you the biggest improvement jump for the least amount of money.

Lessons... where are you located?
Having a good mentor never hurts, but from your description it sounds like you have a general idea of what to look for and what you are experiencing is fairly reasonable for a DA with a stiff diaphragm. Regulator position is one of the most important consideration to performance, but you do need to start with a reasonably good performing regulator (a stiff diaphragm is not going to cut it). The HPR and the newer silicone diaphragm will be a big jump in that direction.

 

[macado]

Definitely agree with Luis, especially since he's the designer of the Phoenix and HPR 2nd stage. You'll like the HPR 2nd stage. You also wont have to deal with horesshoe lever and tab alignment on diaphragm.

Since the Phoenix nozzle was out of stock for a while, I have two DA Aquamasters fitted with HPR 2nd stages along with silicone diaphragms. IP is adjusted so it's 135psi at ~300-500psi. They perform beautifully. I closed off one of the ports on the 2nd stage to get better venturi but it's probably unnecessary. I use them in conjunction with the VHD backplate and run a 3 port LP splitter off hooka port.

 

[herman]

To add a little to Luis's comments. The old diaphragm definitely has to go but once it's replaced, the new one needs to be set up correctly. This is true whether you go with the HPR or replace it with a silicone replacement and keep the horseshoe. I like the second stage levers adjusted so they are almost touching the diaphragm. The easiest way I know to tell is to gently press/tap on the diaphragm with the reg resting diaphragm up. When you tap it you can feel and hear when they meet, keep that space to a minimum but leave a tiny bit as the band clamp will pull it in slightly. If you are using the old style diaphragm it is important to keep the tabs aligned properly. The easiest way I know to do that is to mark the outer edge of the diaphragm (top side) and the bottom lip of the can with a sharpie using a ruler to put the marks in the proper place. When you set the diaphragm on the reg, you align the marks. With the HPR, there are no tabs to align.
Next the levers must move freely. That is somewhat of a science and black art with the old standoffs and horseshoe, with the HPR that issue is eliminated, another good reason to use one. The standoff tabs need to be straight (many were bent in the old days), any knicks removed and they must be aligned straight to prevent any binding, that can at times be challenging since you must tighten the screws and keep them straight at the same time. If you go with the old horseshoe I would suggest you at least purchase a new LP seat holder. Once the supports are aligned and the lever moves freely, you must adjust the lever height with the LP seat nut. The old ones do not have a screwdriver slot to hold them with, that can be a pain plus you must seal the nut somehow...I use fingernail polish. The new replacements have a screwdriver slot and use a nylon lock nut.

Now that you have a properly set up reg you need to dive it some. Besides positioning, the act of breathing from a DH is somewhat different. DHs do best with a loooong slow relaxed breathing rate. It feels different and takes some getting use to...not that it's uncomfortable, quite the contrary, but different and takes a little time to adjust too. I find I keep the rhythm when I swap back to single hose regs. And one final thought, besides having the cans between your shoulder blades they also need to be close to the body. A BP/wing with a STA may position the cans between the shoulder blades but it may also hold it up off your back by 2 or more inches, that is just as bad and IMO worse then the cans being too high.

 

[Luis H]

The breathing performance of a regulator is mostly driven by the second stage.

The only ting the first has to do (and can do) is provide as constant of an Intermediate Pressure (IP) as possible. That is all the first stage does.

The breathing cycle is not a steady state flow so the IP will fluctuate during the cycle. The IP will drop during inhalation. The maximum drop will occur at the peak of the inhalation towards the beginning of the inhalation flow. The better performing first stages will drop less (about 5 psi) than poor performers and the IP rebound quickly.

A balanced first stage provides an IP that is affected very little (or not at all) by the change in tank pressure.

Having a constant (or as constant as possible) IP makes it easier to adjust the second stage so that it delivers air consistently with low suction effort, but what really dictates the performance is the second stage. The mechanical advantage, minute mechanical friction, ultimate flow capacity, venturi flow are all determined in the second stage.

A good second stage can accommodate for a less than ideal first stage, but a great first stage can not do anything to overcome a poor second stage.

---------- Post added June 7th, 2013 at 07:37 AM ----------

Note: with the HPR (and the newer silicone super flex diaphragm) the adjustment of the lever height is not very critical.

As Herman mentioned, the old horse-shoe supports can be critical to adjust to avoid binding (keep in mind the forces we are dealing with a relatively small).

The HPR is self contained and self aligning. There are very little adjustments needed. Most of the feedback that I have received is that the installation is very easy and it performs great with very little adjustments. Some of the responses have been that they could not believe that they were done... no need for extensive fine tuning...

My personal testing and the feedback that I have received is that the performance increase with the HPR is not only noticeable, but it is very consistent.

 

[Six2Life]

I was kinda leaning towards doing the HPR and diaphragm. If I were smart, I would have picked up a new diaphragm when I bought the other stuff. Seems like that one component is essential to have in good shape and pliable.

It appears that a new diaphragm is a given, so I guess my dilemma is do I get a new diaphragm and HPR, or new diaphragm and balanced nozzle? If the RAM nozzle that was offered to me about a year ago is still available (not a sure thing) I estimate that with all the other parts that are needed it would be about a $100 upgrade vs. $50 for the HPR. But if I do the nozzle now and the HPR down the road then is sounds like I should also install the single stage diaphragm with the HPR, so I'd potentially be buying that part twice. I'll have to think about that a bit.

I've been diving the DA with a plastic scubapro backpack that I scavenged from a rotted stab jacket. The first time I used it the rig would seem to shift around a little and sometimes ride up placing the reg closer to my head. Then I added a crotch strap and that seemed to help a bunch with keeping everything in place. I assume the old backpack places the cans close enough to my back?

 

[macado]

You would get much better performance with an HPR and silicone diaphragm. You can always buy Phoenix nozzle later on. If your IP is adjusted properly then you will probably not see a huge difference in performance with the Phoenix nozzle.

Don't get me wrong, it will be better but the HPR/diapraghm will most likely make the biggest improvements. The biggest thing with the Phoenix nozzle is added 3 LP and 4 HP ports to use with modern accoutrements and the balanced first stage along with heavier yoke can be used with HP steel tanks.

Pretty much what Luis said in his last post.

 

[herman]

If you go with a new but old style 2 stage diaphgarm you can still use it with the HPR, all you have to do is turn the tabs out of the way (90 deg from normal). That is what I did with the original HPRs before the new single stage diaphragm was available. HOWEVER, the old style 2 stage silicone ones are not as good as the newer single stage ones so it's a little counter productive to do so. While a RAM nozzle would help, IMO the best bang for the buck is a HPR with the single stage diaphragm. If you still want the RAM nozzle, I am 99% sure it is still available...raining too hard for me to go look now

 

[Six2Life]

Ok, Ok, HPR it is!

Maybe I will do a quick dive with the DA tomorrow so it will be fresh in my mind how bad it is with the original parts.

Thanks for all of the great advice!

 

[Nemrod]

You will never be satisfied with it as long as you are cheaping it out. The original diaphragm is stiff and degraded and must be replaced to get good performance. The HPR is a logical step. Those two things alone make a very large difference. The duckbill is fine but a nuisance when the DBEV is so cheap and easy. Silicone cage valves are essential for smooth and easy breathing. THe DA unbalanced first, I would rather a good RAM nozzle assembly or Phoenix than buying new innards for a now damaged DA first stage.

You probably also need to be shown how to dive it.

N