Voit Trieste IP adjustment

[dhillman]

Hi friends, not sure if this is the right place to post this question. I am trying to adjust the IP on a Voit Trieste, but the 125 psi is at the end when the spring is almost completely compressed and the pressure goes from 40 to 160 psi in a 10th of a turn. When you get it to 135psi, breath and pressure goes down to 40 psi and slowly comes up to 135. Is this normal? Breathing is quite hard with poor amount of air. I haven't tested it in the water yet. Any information regarding this model please reply. Thank you in advanced. Darrel

 

[Luis H]

It sounds like you have a bad adjusting spring (I am assuming that the tank valve was fully open when you did that test).

We have seen very similar behavior on an Aqua Master and Royal Aqua Master. The first stage of the Trieste is very similar and it basically uses the same adjusting screws and springs.

I would try a new adjusting spring. You may be able to get one at VintageDoubleHose.com

The IP swing, during a breath, should not be more than 10 to 15 psi and it should return to the set point very quickly.

Also the IP response that you are describing, when you are turning of the adjusting screw, is typical of a spring working close to fully compressed, were it doesn’t have a linear behavior anymore.




BTW, where in Puerto Rico are you? I was there in April. We went diving in Vieques and in Aguadilla, Crash Boat Beach.

 

[herman]

Now Luis, what would you know about the IP on a Trieste. (inside joke Darrel)

I agree, sounds like a bad main spring, a bad one will do really odd things to IP. I had a Phoenix (modified DA) that did pretty much the same thing, a new spring fixed it, at least the unstable setting. The slow responce 40(which is way too low) to 135 has me wondering if you don't have some other issues as well. Has the reg been torn down and serviced?

Back to the lathe.

 

[Luis H]

Now Luis, what would you know about the IP on a Trieste. (inside joke Darrel)

I agree, sounds like a bad main spring, a bad one will do really odd things to IP. I had a Phoenix (modified DA) that did pretty much the same thing, a new spring fixed it, at least the unstable setting. The slow responce 40(which is way too low) to 135 has me wondering if you don't have some other issues as well. Has the reg been torn down and serviced?

Back to the lathe.

Yeah Herman… why don’t you get back to that lathe?

I was wondering about that (in bold). That is why I mentioned the obvious… is the tank valve fully open... or is there anothe obstruction, clogged filter, etc.

 

[dhillman]

Thank you guys, and sorry for getting back to you so late. I noticed that I am missing an O-ring, #10 at the first stage assembly housing. I will remove the sintered filter an put it in ultrasonic with detergent to clean it. Not sure if the o-ring will separate the housing and give more play to the spring. So the spring we are talking about is the B20112 Spring Diaphragm. I will get in touch with Bryan to see if he can get me that spring. Do you know the part # of the Royal Aquamaster?

Luis, I remember we got contact few years ago and heard that you used to work at Divers Service Center in Puerto Nuevo installing the Hydro tester back in the 70's. I live in San Juan, have my Boat in Villa Marina, Fajardo and dive most of the time in the east of the island. Palomino, Culebra, Icacos, Punta Arena Vieques, etc. I am starting again with photography using my DSLR in an Ikelite Housing. I don't have that much time due to family activities but try as much as I can to dive about 10-15 times a year. I came into the double hose family to get bubbles and sound behind me. I do most macro photography, so I am at few inches from the subject..

Thank you very much for your answer, I hope I can get this regulator into working conditions. I have heard good things about the Voit Triester, and also no such good things, so let see what happens. Thank you in advanced, if you happen to know about where to get this spring , please let me know.

Darrel

 

[herman]

A missing #10 oring is going to give you some real problems -IP would just run away and continue to increase but based on your description I suspect it is inside the reg. The spring we are takling about is the main spring, B20112. The USD equlivent for the DAAM and RAM is #1000-40. My guess is it's part of your problems but there are more issues than just it. At least the one I had, the IP would do OK- stable and adjustable up to 110-120 where it got very unstable, after that it got very unstable. If Bryan can't help you, I have the part number and vendor that sells one that you can use as a substitute- I sourced them when mine went bad and a bunch of us have used them so I know they work.

 

[dhillman]

I feel very good with you two as back-up along with the Service Manual for this trouble shooting. Bryan told me he have some old springs, but never told me to a price for it. I was also thinking in the pin (B20258) length. I felt that the pin was not pushing the seat far enough to let the air in. Tonight I am going to do some tests. Do you think I can try the regulator without the filter just for a test to make sure that the filter is not the restriction? As I said, the only o-ring that looks loose inside the retainer is part #S10121. I will work on it tonight and let you know my findings. I will appreciate all the sources of parts for this unit (Trieste) that you know of. Does the cross cut of the Aquamaster that Bryan have at his site are similar to the Trieste Body???

Thank you again Herman, I appreciate your interest and your experience.

Darrel

 

[herman]

S10121 is a backup ring so it's not ususual for it to be floating, no big deal there. All the parts except BS 2148......poppet retainer....where do they come up with those names....the balance chamber are interchangable with the RAM/Conshelf/Titan. The internal parts to BS2148 (5&6) are interchangable with the RAM/Conshelf/Titan as well although I understand from our Voit expert they are a pain to replace. I really doubt the pin is a problem as long as it is the original, if I remember correctly it sets almost flush with the housing. There should only be a small space between the housing and the button (#13), between 1/16 and 1/32 -not much at all. I would start by seeing if I could get a stable IP, reguardless of value - even 80 or 90 is fine. If it will stabalize and rebound very quickly without dropping more than a 10-15 PSI , then the problem is def the spring. If it stabalizes but takes long time to recover, you have other issues.....does the one you have have the J-valve installed (54-70) or just a plug (72 or73)? A bad J valve could also cause the slow IP return as well. If it has a plug (72 or 73) remove it and make sure it's clean in there, a small piece of trash or corrosion in that area could give you slow rebound problems like you are seeing. As for checking it without the filter, yea you can but I would wait to get my IP stable. A clogged filter will cause a slow rebound and large IP drops but it will not have any effect on the stability of the IP. I would work on getting a stable IP first, even one at a too low but stable value before chasing more problems.....one problem at a time is best.

 

[Greg Barlow]

Herman and Luis have given you some excellent advice. I have dove with both of these gentlemen, and respect their knowledge.

IMO, the entire reg, both 1st and 2nd stages need to be completely rebuilt. To try and "patch" an issue with a regulator that might have been serviced more than 35 years ago is not a wise move. Most of the parts are widely available, and it takes little more time to do a complete overhaul.

With the Trieste, the 1st stage should be rebuilt with a new Aqualung or Mares HP valve assembly. I have used both with excellent results. The advantage of using the AL version is that it does not need a custom length pin to operate properly. Proper hard/soft seat separation is vital to ensure that adequate gas flow is not impaired.

Bryan sells the AL HP valves on the VDH site. I can provide you with all of the proper O-rings (size and hardness specific to each need), along with a pin if you decide to use a Mares Tri-Material HP valve.

When I service a Trieste, or any of the Voit single hose balanced diaphragm regs, I set the IP from 125-30psi. That provides satisfactory performance, and will generally demonstrate around 10-12psi drop in IP while the second stage is fully open.

The Trieste is not a particularly easy breathing DH reg. It suffers from a small diameter second stage diaphragm. Not only does that small diaphragm hamper the performance (decreased surface area), it is of a "bell shape" configuration, which hampers its deflection (inward movement).

Greg

 

[herman]

Speak of the devil
Darrel, let me introduce you to Mr Voit himself. Greg is the man we turn to for Voit questions.

Greg, I have not forgotten about the plugs or the J valve, Luis has me busy on a (Voit) project at the moment but I think we are getting close. So hopefully I can turn to them soon.