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Post by nikeajax on Jan 8, 2019 17:01:18 GMT -8
Phil, could you use one of those star-holder-onners from the 1970's to hold your filter in? Dacor used them for a while: do you know what I'm talkin' 'bout?
JB
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Post by vance on Jan 8, 2019 17:45:55 GMT -8
I do! That's a great idea! I had also thought of using the DivAir fine screens instead of a sintered filter. These things will gain a few much needed thousandths. If the crown block can be cut down enough without holing or being paper thin at the top, this might be doable!
Dang it! I wanted to put this thing to bed!
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Post by nikeajax on Jan 9, 2019 8:43:35 GMT -8
No rest for the wicked  JB |
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Post by luis on Jan 9, 2019 17:02:21 GMT -8
I do! That's a great idea! I had also thought of using the DivAir fine screens instead of a sintered filter. These things will gain a few much needed thousandths. If the crown block can be cut down enough without holing or being paper thin at the top, this might be doable!Dang it! I wanted to put this thing to bed! Be aware that the balancing chamber is exposed to the pressure differential of full tank pressure (minus the IP in the case of a first stage, IP is small anyways). The flat end of the balancing chamber is a small surface area exposed to full tank pressure, but if you are planning on modifying it, I would not ignore the stress level just because it is a small area. The easiest way to calculate stresses on a circular flat disc with fixed perimeter edge is using the equations available from "Roark's Formulas for Stress and Strain" by Warren C. Young. This is not a good candidate to follow a "trial-and-error approach", to determine the minimum thickness needed, to avoid the stress levels that could induce a short fatigue life (mostly due to shear stresses). You cannot even see the balancing chamber when it is pressurized. |
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Post by SeaRat on Jan 9, 2019 17:21:40 GMT -8
I do! That's a great idea! I had also thought of using the DivAir fine screens instead of a sintered filter. These things will gain a few much needed thousandths. If the crown block can be cut down enough without holing or being paper thin at the top, this might be doable!Dang it! I wanted to put this thing to bed! Be aware that the balancing chamber is exposed to the pressure differential of full tank pressure (minus the IP in the case of a first stage, IP is small anyways). The flat end of the balancing chamber is a small surface area exposed to full tank pressure, but if you are planning on modifying it, I would not ignore the stress level just because it is a small area. The easiest way to calculate stresses on a circular flat disc with fixed perimeter edge is using the equations available from "Roark's Formulas for Stress and Strain" by Warren C. Young. This is not a good candidate to follow a "trial-and-error approach", to determine the minimum thickness needed, to avoid the stress levels that could induce a short fatigue life (mostly due to shear stresses). You cannot even see the balancing chamber when it is pressurized. Luis has given a very good reason for not doing this procedure. From my work life in product safety, I would recommend against doing this (trying to get the Healthways into a balanced single stage by cutting down the crown block and using USD parts). Things could go badly, even after a successful test, and it could happen during a dive. John John C. Ratliff, CSP(Retired), CIH(2006-2017),* MSPH Phone: (503) 707-2568 *CSP = Certified Safety Professional since 1986; CIH = Certified Industrial Hygienist |
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Post by nikeajax on Jan 9, 2019 18:28:36 GMT -8
Phil, since everyone's pickin' on you So, here's a thought: could you shorten the length of the HP-seat's shaft some? Just brainstorming here is all!!! JB |
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Post by vance on Jan 9, 2019 21:17:49 GMT -8
I do! That's a great idea! I had also thought of using the DivAir fine screens instead of a sintered filter. These things will gain a few much needed thousandths. If the crown block can be cut down enough without holing or being paper thin at the top, this might be doable!Dang it! I wanted to put this thing to bed! Be aware that the balancing chamber is exposed to the pressure differential of full tank pressure (minus the IP in the case of a first stage, IP is small anyways). The flat end of the balancing chamber is a small surface area exposed to full tank pressure, but if you are planning on modifying it, I would not ignore the stress level just because it is a small area. The easiest way to calculate stresses on a circular flat disc with fixed perimeter edge is using the equations available from "Roark's Formulas for Stress and Strain" by Warren C. Young. This is not a good candidate to follow a "trial-and-error approach", to determine the minimum thickness needed, to avoid the stress levels that could induce a short fatigue life (mostly due to shear stresses). You cannot even see the balancing chamber when it is pressurized. Thanks for the warnings and suggestions, Luis, John, and JB. I appreciate all the help I can get! Just by eyeballing the working space, I have been discouraged from trying to mod the GL valve due to the extremely short space between the retainer clip and the ledge that the balance chamber would have to fit into. I never liked the idea of modifying the balance chamber. There are other possible places to take up the slack, like using screens instead of a sintered filter, a star retainer instead of a circlip, no spring on top of the bc, etc., but the working space in there is short! It would be great to make a balanced valve for the GL, since it is a really great single stage performer. However, the specs on the short valve are just not optimal for converting it to use Conshelf guts. I pursued this mod on the long valve, because the numbers add up very close. I'm only doing it for the challenge and the learning experience. I haven't got it right yet. I need to work on the HP pin, because I misunderstood how the balance chamber works, and how the parts interface. I've got the gist of it now, and should be able to produce the right pin and get a balanced long valve working. I think it would be more logical to put a GL style cap and venturi on a modded long valve than to try to mod the short GL valve. However, there are many hurdles and a lot of figuring to do with this too. I really doubt I want to follow through with it, but you never know. I always say that, then I do it. |
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Post by nikeajax on Jan 10, 2019 9:23:19 GMT -8
Phil with a snorkel-jet, your Scuba-A could be totally rockin'!  It would be a real sleeper, like the 1957 Rambler Rebel, they car that broke so many Chevy owners hearts!   JB |
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Post by vance on Jan 11, 2019 11:09:17 GMT -8
Hey! I was one of those Chevy owners! Of course, my '55s and '56s were already nearly 15 years old by the time I got 'em. They were all hotrods, and had none of the original drivetrains. My favorite mod was a "high-performance" 348/Saginaw 4 speed/ 4:11(??) positraction differential package I dropped into a '55. That 348 was BIG (same physical size as the 409). It wasn't the usual way to go, so I liked it (and I got it for free). Even with 2, 4 barrel carburetors it wasn't a thrilling performer.
I have owned a couple Ramblers in my time. Not the Rebel, though. I had a station wagon (1960-ish) and a 1965 convertible. They were not my favorite cars. Incredibly, the stick shift cars still had torque tube driveshafts in the '60s. You had to pull the rear end to change clutches!
Healthways, the Rambler of regulators. Got to bring the thread back around!
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Post by vance on Jan 25, 2019 17:12:50 GMT -8
I got the 1/16" stainless hardened steel rod, and made a working pin out of a Healthways pin I got out at the source of all wonderful things. This pin is like nothing I have ever seen, but looks sorta like the Healthways DH pin, but different. I will post pics.
This time, I got it right. The stainless rod fits up inside the Conshelf soft seat, and is the correct diameter to let a bit of air into the balance chamber. I got balance chamber float, I got the correct pin, and it should be a working balanced single stage valve. It works in the regulator and breathes fine.
I have to admit, my understanding of the balance chamber is fuzzy. I understand now WHAT is supposed to happen, and have made sure it does, but I am not completely sure WHY it works to balance the stage. This is nothing new. I have been operating in this state for many years and with many things.
Are manometer tests to follow? Uhh... Maybe? I'm thinking that the Misuba Rev3 Snorkeljet will get this valve.
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Post by vance on Jan 25, 2019 17:33:32 GMT -8
I'm thinking that the Misuba Rev3 Snorkeljet will get this valve. Making it the Misuba rev4? |
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Post by nikeajax on Jan 25, 2019 17:48:40 GMT -8
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Post by vance on Jan 25, 2019 18:01:50 GMT -8
I was lying awake in the middle of the night thinking about how I can get this to work in the GL valve. There's got to be a way....
The problem is the very limited space at the top of the GL valve for the balance chamber. There might not be enough room even for a non-floating block, requiring cutting down the balance block somewhere. I've already been warned to do calcs on thinning the top. But, maybe there is a bit of wiggle room at the bottom, or by cutting a new ledge inside the valve body?
As I understand it, for wiggle room (a very handy term), in a balanced valve, the balance chamber has a bit of float (or travel) to compensate for too much travel by the demand levers/actuating pin to prevent bottoming out. The Conshelf block has plenty of room in its native valve body, and even has a spring on top to keep it in place until more travel is needed. That's the "float". The long HW valve also has plenty of room (almost exactly the same as the Conshelf) to provide this float. The GL doesn't have any "wiggle room" or really enough space to accommodate the balance chamber block. This means something's gotta give.
What is going to give? The balance chamber block might be cut down, or the space for the block increased by machining/lowering the ledge, or...? This also suggests that the pin travel might need to be limited. If there's nowhere to go, though, it is automatically limited, right? But, what is the result of that? Dunno.... Gotta think on that!
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Post by nikeajax on Jan 25, 2019 18:21:13 GMT -8
Could you perhaps shave a few pahgillionths off the ambient side of the valve seat?  JB |
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Post by luis on Jan 25, 2019 21:26:10 GMT -8
The balanced chamber is not intended or designed to float. The short spring on a Conshelf is just intended to take up the gap from the tolerances. It allows looser tolerances without ever having an interference fit. The Voit MR-12, Titan, Trieste, have a very similar balanced chamber (first stage design) but they don't use the small spring on the back side. You can actually assemble a Conshelf 1st stage without the spring and will work fine. The gap is minimal and tank pressure will keep the balance chamber pushed hard against its supporting ledge. I will give a quick hint of how the balance chamber works: It is a, mechanically supported, low pressure chamber behind the HP seat. On the front of the HP seat inside the volcano orifice is low pressure air. By having a low pressure chamber behind the seat, the pneumatic forces applied to the seat are now balanced. The seat is not affected by tank pressure. The tank pressure is only pushing around the perimeter of the seat, not pushing it, to close or open. I hope my explanation is clear. I highly recommend reading the "Regulator Savvy Book" by Pete Wolfinger. www.scubatools.com/c-23-regulator-savvy-book.aspxIt will explain how regulators work. I highly recommend reading this book. It explains a lot about the pneumatic forces and how they interact to make a regulators work. Please don't take this in a wrong way, but for your own safety, IMHO I feel that you should try to understand how pneumatic devices work before making major modifications. Just be careful (always wear safety glasses, etc), you are now working with high pressure air. |
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