|
|
Post by vance on Jun 4, 2021 16:18:36 GMT -8
OK, since things are slow here, I thought I'd post about a little project James and I have been working on. This is the precursor to the "whole cloth regulator" challenge that was made a while back. While it isn't a completely homemade regulator, it is intended to be proof of concept for a 3D printed single stage valve and regulator. So far, we have some original parts that will convert a 2 stage DA valve body into a single stage regulator. We have experimented with a Healthways single stage lever system, and I have made a custom lever set, as well. The idea is a plug that screws into the IP seatholder hole, and provides a mount for the lever base. Here's a delrin version on top of a 3D plug:  I made a brass guide that presses into the plug, and made an HP pin to fit.   Then the lever is attached, and a 3D printed air director (as shown) or a modded USD second stage body is used to direct air into the intake horn.  I will explain more as we go if anyone is confused. Since James is the 3D print guy, and I am the metalhead guy, we have collaborated on the parts that need to be produced for a working version: he has printed some parts, and I have turned some. James' setup is based on the HW levers, and mine on my custom set. Mine uses his adjustable air director, but I will probably make a metalhead version! |
|
|
|
Post by SeaRat on Jun 4, 2021 17:52:00 GMT -8
Okay, this is really interesting. It looks like this will be a very efficient single stage regulator. I have two questions:
1. Will it be equipped to handle 3,000 psi?
2. Will you use a Mistral-type Venturi on the blue section, or a custom one? If custom, can you change the Venturi?
John
|
|
|
|
Post by vance on Jun 4, 2021 20:27:44 GMT -8
No, no venturi tube. It isn't necessary. The screw you see on top of the air director is a secondary jet with the screw as an adjuster. This allows tuning of the primary jet, which is very strong. Other jets might be necessary, but so far it looks good.
It can be built on an unbalanced (DAAM) or an balanced (RAM) nozzle. The HP pin needs to be different for the two, of course.
A Conshelf yoke will provide enough strength for 3K, and with a balanced RAM nozzle, this should work fine at 3,000 psig.
Much of this concept is James' idea. I have contributed with some of the functional aspects, testing, and refinements.
James will probably come up with a printed conversion kit, and I will make a metalhead version. His will utilize HW levers or some other system, while mine is going to use a refined version of the pictured SS steel custom lever set.
|
|
|
|
Post by luis on Jun 6, 2021 7:34:15 GMT -8
When you get it setup and ready to test, you should place an LP adapter in the hookah port and monitor the dynamic pressure with an IP gauge.
I realize that intermediate pressure is not normally what we think about with a single stage regulator, but I have measured it and it can be substantial, during the dynamic flow while inhaling.
I have measured the “intermediate pressure” (IP)in a modified Mistral type of regulator and during a normal breath the momentary pressure can range between 60 psi to about 130 psi, depending on how hard I am inhaling. I have seen it go as high as 180 psi (maybe a bit more) when I induce a free-flow.
This is a very transient pressure, but you can sustain it as long as you are inhaling.
We called them single stage regulators, but a more accurate description is single valve. The actual pressure drops occurs in at least two very discrete stages or steps.
The first significant pressure drop (compressible flow type of pressure discontinuity) occurs around the perimeter of the valve volcano orifice. The second pressure discontinuity occurs at the jet opening due to a second sudden pressure discontinuity.
BTW, the nozzle or blue plastic piece should have no issues handling the pressure since the area is relatively small.
The piece that is guiding the pin will see the same pressure, but the area is substantially bigger and there are fewer threads. It may not be an issue (and I have not done any specific calculations on the shear stress of these threads), but the pressure could be an issue with that large disc in 3D printed plastic. Just be careful when testing.
|
|
|
|
Post by vance on Jun 6, 2021 14:44:10 GMT -8
Thanks for the comments, Luis. It's always good to hear from engineers on these mods.
If there could be a problem with pressure on the 3D plug (which isn't much of a concern to me, since there's a lot of threads on the plug), a delrin plug will certainly handle far in excess of 200 psig. I agree that the air director is fine, whether it is 3D printed or a modded DAAM second stage body.
My concern is the HP pin, and what pressures are exerted on it at depth. That is why I put it in a brass guide (which extends into the nozzle a little), made the upper portion 1/8", and narrowed it down to the 1/16" required by a RAM seat. It should be held rigid along most of its length. 1/8" also works well for the lever set screw contact.
|
|
|
|
Post by vance on Jun 6, 2021 16:07:36 GMT -8
I guess the question here is "Why?". Well, you know me. And James. It's all about doing something different, and having fun with it. Like others, (Herman is a good example), I want to make mods that improve older designs, like making the DH regulator Dacor could have made out of the Dacor 4/800. Or, I like to think about how to recreate a great regulator, and then improve on it, like my balanced Healthways GL mod. The RAM to SSAM conversion with a suitable yoke gives us a 3K PSIG compatible, balanced single stage regulator ( with a DBE!) built on USD parts. The DAAM to SSAM is not balanced, but it is a Mistral equivalent reg that works well with a DBE and lower tank pressure! That's why.  |
|
|
|
Post by vance on Jun 16, 2021 15:55:20 GMT -8
So, I'm looking at the SSAM conversion sitting on my desk, wishing I could pool test it. F'in cast... The pools are open and available.
I'm scheduled to get my cast off tomorrow, b/c I convinced my rather crabby Orthopod doc to take it off early so's I can dive in Cabo next week. You don't know the promises I had to make to get her to capitulate.
Never mind, that's between her and me.
After a week in paradise, I should be able to pool test the SSAM. I think it's going to be a winner.
I'm somewhat surprised there's so little interest in this. A 3K, balanced single stage with an LP port is pretty awesome?
|
|
|
|
Post by james1979 on Jun 17, 2021 10:38:39 GMT -8
Sorry I haven't pool tested mine yet. Too many projects stacking up (and too many are house related, not hobby!). I'll try to get to it in the next week.
|
|
|
|
Post by nikeajax on Jun 17, 2021 10:57:42 GMT -8
...Too many projects stacking up ( and too many are house related, not hobby!)...  JB |
|
|
|
Post by vance on Jun 17, 2021 15:52:34 GMT -8
OK! Biff, which is what I named my cast, is gone. We are through! I laughed while Biff was dismembered and thrown into the trash. I'm not sorry for Biff at all.
We leave for Cabo Saturday. I have a splint, which I promised my Doc I'd keep on except when in the water. Ha! I'm going to be in the water all the time.
I want to do some tank dives around Los Arcos, and I'll snorkel till the cows come home.
When I get back, I'll do a SSAM test in the pool. We need to find a spring that will allow a reasonable cracking pressure, but the stock spring is fine for now.
|
|
|
|
Post by luis on Jun 18, 2021 9:46:33 GMT -8
If you are referring about the spring that closes the first stage valve in a Conshelf/ RAM type of first stage, you need the full spring force for the valve to close and seal with a high pressure cylinder. That spring (not the tank pressure) provides the only force that closes and seals the first stage valve. I have in numerous times service a Conshelf or a RAM type first stage and it worked great with most tank pressure, but the last step I take is always to test it with a full 3000 psi or better yet, a 3400 psi cylinder. And several times the first stage has a small first stage valve leak with the higher pressure cylinder. I test it again with 2000 psi or even 2500 psi and it seals great with the lower pressure. I replace the spring that holds the valve closed with a new one and problem solved, easy fix. It requires that amount of force to create a reliable seal between the HP seat and the volcano orifice (and tank pressure is not assisting with the force).
Sometimes the old springs get a bit compressed and are not applying the same force on the back of the seat.
The high pressure seat leak is persistent even with the IP adjustment spring fully retracted. So the same would happen in a balanced single stage.
The only reasonable (or easy way) to lower the cracking effort in a truly balanced single stage is to change the mechanical advantage of the lever system. The force required to open the Conshelf style valve is fairly constant and independent of cylinder pressure. It is about 8 pounds all the time. So it is not difficult to see that by changing the mechanical advantage you can change the cracking effort. I know, I have been there, done that… but I didn’t get the T shirt…  Good luck and have fun.
|
|
|
|
Post by james1979 on Jun 18, 2021 11:02:09 GMT -8
If you are referring about the spring that closes the first stage valve in a Conshelf/ RAM type of first stage, you need the full spring force for the valve to close and seal with a high pressure cylinder. That spring (not the tank pressure) provides the only force that closes and seals the first stage valve. I have in numerous times service a Conshelf or a RAM type first stage and it worked great with most tank pressure, but the last step I take is always to test it with a full 3000 psi or better yet, a 3400 psi cylinder. And several times the first stage has a small first stage valve leak with the higher pressure cylinder. I test it again with 2000 psi or even 2500 psi and it seals great with the lower pressure. I replace the spring that holds the valve closed with a new one and problem solved, easy fix. It requires that amount of force to create a reliable seal between the HP seat and the volcano orifice (and tank pressure is not assisting with the force).
Sometimes the old springs get a bit compressed and are not applying the same force on the back of the seat.
The high pressure seat leak is persistent even with the IP adjustment spring fully retracted. So the same would happen in a balanced single stage.
The only reasonable (or easy way) to lower the cracking effort in a truly balanced single stage is to change the mechanical advantage of the lever system. The force required to open the Conshelf style valve is fairly constant and independent of cylinder pressure. It is about 8 pounds all the time. So it is not difficult to see that by changing the mechanical advantage you can change the cracking effort. I know, I have been there, done that… but I didn’t get the T shirt… Good luck and have fun.
Luis, I agree on the RAM/Conshelf first stage, but just to clarify Phil was talking about the DA first stage (what we are currently using in this project). Being un-balanced, tank pressure is helping hold it closed.... I'm actually running a much weaker spring in this one, with noticeable results to the cracking effort. When we switch over to RAM nozzles (or Cyclone), I totally agree that factory springs are the way to go (due to the afore mentioned balancing). Respectfully, James |
|
|
|
Post by vance on Jun 18, 2021 12:09:17 GMT -8
Mine now sports a RAM nozzle, so it will need the stock spring, I guess. I can easily go back to a DAAM nozzle since I have several set up.
My compound levers are pretty similar to the Healthways levers James is using, and both should provide pretty good leverage. Just pressing the levers down with a finger feels pretty tight, but it needs to be tested on a tank.
Charlie sent me a manometer a couple of weeks ago, but I haven't set it up. My tanks are all pretty empty now, since I haven't been able to get fills recently. The county is supposed to be allowing fills about now, so I should be able to get some air soon. I'd like to see what the SSAM cracks at!
|
|
|
|
Post by luis on Jun 19, 2021 8:34:43 GMT -8
Here is a post I made almost 10 years ago, showing how I measured the force required to open the valve. The 8 pounds of force on the balanced first stage is fairly consistent. I have measured it on a number of regulators. It varies a little bit with pressure because it is not perfectly balanced, but it is not much
The force on the DAAM varies inversely proportional to the tank pressure. I have the data with tables and graphs.
From calculations, I can tell you that the working area of the ambient pressure diaphragm is about 13.8 in^2.
Just to give some basic math, with that area, it takes about 1 inWC pressure differential to develop a bout 0.5 pounds of force on the lever.
Since it is proportional, you can easily determine the maximum force on the lever that correspond to the pressure differential that you are designing for.
So here is basically all you need to determine the required mechanical advantage for you lever design.
|
|
|
|
Post by vance on Jun 21, 2021 16:41:09 GMT -8
Thanks for that information, Luis. That gives me some ideas about measuring the things I need to know. Your input is always appreciated!
|
|
