Voit Trieste regulator questions

[crabbyjim]

I recently acquired two Trieste regulators, one of which has a j valve (but is not the Trieste J model).  Not the easiest breathing double hose but not bad either.  I have some questions which I have not seen addressed on this forum.  
1.  The factory hp and lp ports are on the right side.  The hp port is no big deal, but the lp on the right seem suited for a safe second or the inflator for the old USD horsecollar.  If memory serves, we didn't use safe seconds when this reg came out and the USD horsecollar inflator hose was on the right side.  Can anyone tell me why these came off the right side of the reg (other than the fact that the j valve was on the left side?

2.  Many people have mentioned that the Trieste is a hard breather.  SeaRat has built his own diaphragm and there are other fixes available.   Does the Voit MR12 main diaphragm fit the Trieste?  If anyone has any other info on this very cool but flawed reg I would like to read it.

Thanking you all in advance,

Crabby Jim


"Don't worry, be crabby!"

[nikeajax]

Hi Jim, you can find a diaphragm here:

thescubamuseum.com/products/TRIESTEdiaphragmPICTURSE.htm

Not that I have one, but I've heard the OEM diaphragm was a real piece of ca-ca, and added to its difficulty in cracking effort.

I think John fixed his by closing off one of the ports in the valve body: I'll let John elucidate about this...

JB

EDIT: I don't think they intended their design to incorporate the use of a BCD: I was just looking at my Titain-II...

[SeaRat]

Crabb Jim,

A couple of thing.

--The Trieste-J may have a problem with the J-valve. We have documented here at VSS that the seat of the AMF Voit J-valves and Trieste/Tital first stages with the J-reserve deteriorate over time, and disintegrate. This prevents the true function of these J-valves (they leak air).

--second, as Jaybird so nicely illustrated above, the problem of not having a left-facing LP outlet is completely solved with the longer LP adaptor. Dacor and Scubapro both manufactured those, and they may still be available new. The LP inflator hose then routes under the valve body to the left.

I have written extensively about the other mods I have made on my Trieste II:

Gary,

There are three design problems with the Trieste II:

--The diaphrigm is built too "stiff." It has a permanent flex which must be overcome with suction pressure. This amounts to about 1/2 inch of water pressure added to the mechanism.

--The demand venturi is not correctly set. There is too much venturi going into the case, and not enough down the hose.

--The venturi vent can move a bit, and not be pointed directly down the hose. The grove on the side is not quite right for the correct setting.

Here's how I overcame these problems:

--I manufactured a new diaphragm out of waterproof, flexible material. I attached the metal part of the diaphragm with glue (I got the metal part from a different old diaphragm; and kept the original intact). I greased both sides of the boxes, and put then put a "shoegoo" rubber cement onto it, placed the diaphragm onto it, then put the bottom box on it, and a book or something onto it. I let it dry for 48 hours, then trimmed off the excess material, opened the boxes, and removed the diaphragm. I let it "cure" for another 48 hours, then assembled the two. Dan overcame this by changing the case, and in doing so changed the diaphragm. I like my way better, as it preserves the character of the regulator. This resulted in much better performance, especially with the other three measures I took.

I years ago sent my Trieste II to a shop in Vancouver BC. They specialized in a modification which involved plugging one of the venturi ports on the side. They used soldier (use a lead-free variety). This increases the amount of air directed down the hose.

I placed a block in the mouthpiece to keep air from going into the exhaust hose. I used the same block that is found in a Healthways SCUBA Delux two-hose regulator, but I glued it into the AMF Voit mouthpiece. It is a round plexiglas disc with holes about 1/16th inch in diameter around the perifry of the disc. This blocks the air from going down the exhaust hose, and channels it into the mouth.

Finally, I fine-tuned the LP port by screwing it out until it matched the interstage pressure. I then exactly matched it to the opening of the inhalation hose (it moves about 1/8th inch).

With these fixes, which I've been using for about 15 years now, this becomes my favorite two-hose regulator. It pulls about 1/2 inch of water suction pressure. I recently upgraded it with Dan's grey hoses (boy to they look good), and a new flutter valve (Dan's fit the Trieste II very nicely, and are sturdy too).

Good luck with it.

John

Read more: vintagescuba.proboards.com/thread/223/trieste-2nd-stage-adjustment#ixzz4R9RzhnYH

I will post photos later when I get off my iPod and onto my main computer. But the Trieste can become a wonderful regulator.

John

PS, the Voit MR-12 diaphragm for the second stage will not fit the Trieste. It is a unique diameter, and I therefore had to make my own LP diaphragm, which is still working. You can buy a new second stage silicone . diaphragm from The SCUBA Museum, but I have heard that it too may be stiffer than necessary. The SCUBA Museum also offers a new plastic body with a larger diaphragm for the Trieste, and that option, while more expensive, looks good to me. But the design shortcomings of the nozzle would also, in my opinion need to be addressed.

PS2, the "block" I mentioned above in the mouthpiece is technically a "deflector plate," and serves to deflect air rushing down the intake hose into the mouthpiece opening.

[crabbyjim]

John,
Thanks for putting all this info in one place. I have seen most of it after hours of sifting throuth this and other forums. The j valve seat problem is fixuabe with access to the right parts (as you and others have mentioned). I think a read that the j valve can be replaced with either a plug or an adapter. Dan serviced the first reg for me but we didn't manufacture a new diaphragm like you did. I am planning on having him use the new can with the larger, silicone diaphragm when I send the next one for service.

Do you have any idea why the ports are on the right?

[SeaRat]

The ports are on the right because the design engineers had not taken into account the need for a BCD. This was still in the era when we were wearing an inflatable vest. I bought my Trieste II new in the mid-1970s, and am still using it. Here's a video I made of salmon kills, but used my Trieste II on the dive.


Here's the modifications I made to the second stage:


Here is my Trieste II mounted on my PJ jump tanks. Note the one LP inflator line going off to the right, under the regulator body.


Here you can see the main rearward opening completely blocked off.


The left-side opening has been slightly enlarged.


The right-side opening has been left as it was originally.


This is my home-made second stage diaphragm. I started with a coated nylon fabric, much the same as the neoprene-impregnated nylon diaphragm material for the original MR-12 regulator LP diaphragm. I then coated the surfaces of the Trieste II's sealing surface with silicone grease, then put a layer of clear ShoeGoo on the bottom box. I carefully fitted the original plate onto the diaphragm and sealed it there with, again, clear ShoeGoo. After it was cured, and just after I put the layer of ShoeGoo on the box, I carefully fitted the diaphragm material with the plate roundly in the center, and pressed it slightly into the ShoeGoo on the box. I then placed another layer on top of the diaphragm, and fitted the top box (exhalation box) onto the diaphragm (after also coating the surfaces with silicone grease). I gently pressed these together, and left them in place for at least 48 hours. I then carefully peeled off the top box (exhalation box), then also carefully separated the new diaphragm from the bottom box. I could then trip the diaphragm, replace it, and use the metal ring to completely capture it. I have had no problems with this diaphragm in the over ten yours I have been using it.


Here is a top view of the diaphragm.


A close-up view of the ShoeGoo sealing surface.

'Hope this helps. By the way, Dan has seen this regulator and serviced it.

John

[SeaRat]

Also, here's the Parts Diagram from AMF Voit for the Trieste regulator.



John

[crabbyjim]

John,
Thanks for the pictures.  When I learned to dive in 1969,  we used USD Mae Wests with ties, not zippers.  That came later.  My first regulator was a Calypso J, with an hp port on the bottom and no low pressure port.  The USD horsecollar i used mid 70's to 1990 had the oral inflator on the left (port) side and the Schrader valve power inflator on the right (starboard) side.  So, if the Trieste design predates power inflators, what was the purpose of the lp port?  Does anyone know the answer?

Crabby Jim

[SeaRat]

Nov 26, 2016 19:35:44 GMT -8 crabbyjim said:

John,
Thanks for the pictures.  When I learned to dive in 1969,  we used USD Mae Wests with ties, not zippers.  That came later.  My first regulator was a Calypso J, with an hp port on the bottom and no low pressure port.  The USD horsecollar i used mid 70's to 1990 had the oral inflator on the left (port) side and the Schrader valve power inflator on the right (starboard) side.  So, if the Trieste design predates power inflators, what was the purpose of the lp port?  Does anyone know the answer?

Crabby Jim

Crabby Jim,

This was in a transition phase, and we (I was writing about this for "NAUI News") had started using octopus regulators. So I think that was the purpose for the LP outlet. As I said above, I was using an adapter from the beginning with this regulator. Yo u have to remember that the only other two hose regulator with both LP and HP ports was the then discontinued Sportsways Hydro Twin. (The Nemrod Snark III also had a LP Oort, but it was taken by the overpressure relief valve, though with an adapter you could get multiple LP ports onto it. They called the Snark III a three stage regulator, but the third stage was the overpressure relief valve.). But BCDs were in their infancy at that time. My BCD was the full back of my wet suit, which was a sandwich of 1/8 inch neoprene with an inflator hose, buil by Bill Herder of Deep Sea Bill's in Newport, Oregon. Cave divers and wreck divers were demanding octopus second stages, and Voit put that into the Trieste regulator (and the Titan, which had the same first stage).

John

[nikeajax]

Funny thing about the Sportsways/Water Lung; the Navy Unit had all the extra ports most modern-divers would want in 1966 after they got rid of the tilt-valve and no longer needed the pressure relief valve on the first stage.

JB

[SeaRat]

Nov 26, 2016 22:21:12 GMT -8 nikeajax said:

Funny thing about the Sportsways/Water Lung; the Navy Unit had all the extra ports most modern-divers would want in 1966 after they got rid of the tilt-valve and no longer needed the pressure relief valve on the first stage.

JB

So did their Duel Air double hose unit, although the LP outlet did need the overpressure relief valve as it too was a tilt valve. By keeping the body, and designing into it a nalanced first stage along with a downstream second stage, Sportsways' next generation, the Hydro Twin, had both the LP and HP outlets.

AMF Voit, while retaining the righzts through U.S. Divers Company to produce regulators with the Cousteau-Gagnan exhaust, broke out with their own design with the Trieste/Tital regulators, which have the same first stages. Being a balanced first stage, the Trieste was a direct competitor with the Royal Aquamaster. And, the Trieste could also be upgraded to a J-valve regulator. From a marketing perspective, the Trieste was a dream regulator for those who loved the double hose regulator. I was very disappointed when I found out that my Trieste breathed harder than the Aquamaster, or even the Healthways SCUBA regulator. That began my long search to figure out why it was breading that hard, and what I could do about it. Now my Trieste II is my best double hose regulator.

John

[luis]

Nov 26, 2016 19:35:44 GMT -8 crabbyjim said:

John,
Thanks for the pictures.  When I learned to dive in 1969,  we used USD Mae Wests with ties, not zippers.  That came later.  My first regulator was a Calypso J, with an hp port on the bottom and no low pressure port.  The USD horsecollar i used mid 70's to 1990 had the oral inflator on the left (port) side and the Schrader valve power inflator on the right (starboard) side.  So, if the Trieste design predates power inflators, what was the purpose of the lp port?  Does anyone know the answer?

Crabby Jim

The same first stage for the Trieste was used on the VOIT Titan single hose regulator. The port on the right was for LP hose feeding the second stage of the Titan.

Voit sold both regulators during the same time period and they shared the same first stage. There was no point on doing a separate production run with different machining. It would not have been cost effective.

The later Titan has a plug where Trieste second stage would be installed. The very early ones actually had a disabled Trieste Second stage to close that port.

Take a look at the pictures of the Titan above. You can see the black plug where the Trieste second stage would be installed.

[crabbyjim]

Luis,
Thank you for your input. Once again, the answer appears to be economics. Now I have to acquire a Hydro Twin II like Robert's.

Crabby Jim

[SeaRat]

I have a couple of other things to say about these modifications for the Trieste. If you make these modifications, the venturi will be much more powerful, and you will experience blow-by into the exhaust hose and out of the regulator without some modification to the mouthpiece. I used a Healthways baffle plate from the Healthways mouthpiece to control this, and glued it into the AMF Voit curved mouthpiece. The Healthways mouthpiece (third generation Healthways Gold Label SCUBA) had a groove in it to hold the baffle plate. But the curved Voit/USD mouthpiece did not, and I simply glued it into the center of the mouthpiece. I do not recommend this for anyone else. Here's why.

Several years back, I dove with Bruce Higgins on his Saturday projects at the Edmonds Underwater Park in Puget Sound, Washington. He had us doing several things, and then we ventured out into deeper water where a cabazon was guarding its nest, and it would attack us if we got too close to the nest. This was interesting, and I was wearing my twin 45s and so started getting low on air. We started swimming in toward shore, and I was at about twenty-five feet, when I went to inhale and...nothing. My Trieste II did not give me any air at all. I quickly switched to my MR-12 second stage, and finished the swim into shore, still several hundred yards away. When I got back to shore, I told Bruce about this malfunction. At home, I took took the mouthpiece apart, and found that the baffle plate had come loose, and was lodged up against my intake mushroom valve in such a way as to make that valve unable to open. It had adhered to the downstream side with hydrostatic pressure alone, sort of a vacuum, and no air could come out through the regulator. Well, I replaced it into the mouthpiece, and re-glued it, and so far it has been fine.

BUT, this makeshift solution is not a good one, and I will be changing it soon. Why? Because there is a much more elegant solution, the Argonaut DSV mouthpiece that Luis has designed. I am going to ask Santa for a present this year, and it is the Argonaut DSV mouthpiece, to replace my home-made mouthpiece/baffle plate. I did not use the Healthways mouthpiece with its deflector plate and the associated groove because it was too small, and will not pass enough air without completely removing the non-returns and their associated wagon wheel. Rather than spend any more time on this, I will get the Argonaut DSV mouthpiece. For anyone modifying the Trieste to get a better venturi flow, I would also highly recommend procuring this mouthpiece designed by our fellow vintage diver, Luis Heros, at the VDH website (links are above).

John

[crabbyjim]

John,

What is the advantage of the DSV mouthpiece? I just happen tp have one and I will test it tomorrow.

Crabby

[SeaRat]

Crabby Jim,

My understanding from Luis is that it incorporates an airflow diverted which eliminates blow-by of Venturi air into the exhaust loop.

Maybe Luis can amplify and add to this part of the discussion.

John