Vintage Double Hose

I recently re built an early model DA Aquamaster, it is probably a 59 model. Rechromed and rebuilt with all the usual VDH gear, service kit, DBE, all new silicone parts. It locked in pretty well straight away at 140 PSI on a 500PSI tank. Took it on a couple of dives and it was just about as good as my phoenix - a reallt nice reg to use. Yesterday I went to take it for a dive and hooked it up to a low pressure tank to check it out and all good. I put it on a 3000 psi tank and left it for about 10 minutes before I went to use it. Checked it again and there was hardly any air coming out of the reg. A very slow feed and not enough to sustain breathing. Put an IP gauge on it an it was low so I fixed that, but still hardly an air coming out. On purging an Octo second stage the IP went to zero straight away and then bounced back. It looks to me to be a first stage issue and at this stage I'm thinking it could be the HP seat jamming. I've never had a reg recently serviced that works really well and then seize up like this. I'm looking for comments prior to me stripping it down so that I might know what else to look for. Thanks in advance.

My bet is on a defective main spring. I have in the past had a defective main spring that did some strange things, IP was all over the place and never stable. The spring itself looked good but it some parameter had changed to the point it would no longer work properly. If you have another spring, swap it out and see what happens. I sourced some new springs when I had my issue, Bryan now stocks them I believe.

Thanks Herman, I'll change the main spring and see what happens

Yep; it's a good possibility that it's the main spring just like Herman said. I had a similar problem a couple of years ago with my Voit Navy; drove me nuts! After checking everything, and resetting the IP numerous times the problem was finally nailed down to this spring. For whatever reason it just wasn't functioning properly as a spring, and my IP was eratic as hell. I replaced this spring and the problem went away. Good luck! Terry

I'm very interested to see what fixes this, so please throw a few photos up when you crack the code. These old regulators have so little in the way of issues that I am always curious to see what resolves one when ones does

I took Herman's advice and changed the main spring and also changed the nozzle spring while I was at it. Just put it back together and it works great. Plenty of air and holding 140 psi on a 500 psi tank. Thanks Herman, you saved me a lot of guess work. Now to get it wet.

I posting this in this thread because it sounds like the same or similar problem.

- First Stage DA AquaMaster Locked Up? I think it's your high pressure seat. Just fixed a recent one and the problem was the seat.

- I had this happen with the first DA-AM I rebuilt about 3-4 years ago, ended up sending it in for repair but the tech found it to be working fine. assumed it was an assembly problem and I must have put it back together right before I sent it off for repair. I had heard about the high pressure diaphragm spring as a possible source and bought a new one to swap in. It was already working fine though, so I never knew for sure what the problem was.

- Update to March 2016... My friend Rich brought his new DA Aquamaster to Cozumel. We had done nothing more than to "service" the reg because it was so nicely preserved and it worked great when we put it on a tank. BUT, we had not tried it on a 3,000 psi tank. And when he hooked it up to a tank down in Cozumel, it locked up the first stage and would release no air to the second stage. We had to crank the yoke screw and blow an O-Ring to get it off the tank... Same exact problem as my DA-AM had 3-4 years ago.

- Since there never had been a definite solution, I was back to the drawing board. I swapped in springs, diaphragm, pins, mushroom tops, nozzle bodies... Thinking maybe something dimensional was the problem or something binding and not moving freely. Nothing worked.

- Then over night I couldn't stop thinking about it and I came to the conclusion that whatever the problem was, it had to be in the first stage nozzle. I took that all apart again and everything was assembled correctly and moving freely. So, I put it all together and hooked it up to a 3000 psi tank... Just the nozzle, with a yoke, and with the pin and mushroom top assembled into it. I pushed on the mushroom top and it compressed the high pressure seat normally... Just the way it is supposed to. But no air came out. Usually you can turn the pressure on and then off and then pressing the mushroom top will cause the trapped air to pop out with a sound like an O-ring blowing. How could the seat be moving and not open up the air flow?

- I concluded that the soft seat material was somehow staying sucked against the orifice even thought the seat body (metal part) was moving away from the orifice just the way it is supposed to.

- I quickly swapped in a different high pressure seat and tried the same test. POW! Pressing the mushroom top now opened the orifice perfectly and the air popped tight out. I did the test a few more times to be sure. Then I re-assembled the nozzle into the regulator, hooked it up to a 3000 psi tank, and it worked perfectly. Eureka! A definite cause and solution to the locked up DA-AM first stage.

A weak or short spring and cause problems. The spring and the IP pressure behind the diaphragm balance each other. If the spring is weak and lost some length what can happen is in trying to get the IP set the spring can be compressed into coil bind. Each coil is touching the next and now instead of a spring you have a solid spacer.

captain wrote:A weak or short spring and cause problems. The spring and the IP pressure behind the diaphragm balance each other. If the spring is weak and lost some length what can happen is in trying to get the IP set the spring can be compressed into coil bind. Each coil is touching the next and now instead of a spring you have a solid spacer.

- On this one I swapped in 3 different springs from three different DAAMs that are working great. This did nothing to solve the problem. I removed the nozzle from the regulator body and attached it all by itself to the tank. Opened the valve and pressed the mushroom top to open the orifice... It moved fully but no air came out. Really strange but this test reduced the cause to the only thing left that it could be: The HP Seat. Replacing the seat instantly solved the problem. It worked properly with three different other HP seats, too. Then I put the bad seat back in and the problem returned. So, it definitely was the HP seat... At least in THIS regulator.