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Post by vance on Jul 7, 2020 16:42:52 GMT -8
Herman will see this. It's totally up to him. I don't want to make these myself. It's too much of a time commitment. I got dinged today by my wife for spending too much time in the shop. She thinks I need a new hobby. Like home improvement.
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Post by luis on Jul 8, 2020 10:27:00 GMT -8
It would be a very good upgrade to change the fixed volcano orifice to an adjustable type. I always wondered why Aqua Lung (US Divers) never changed the “non-adjustable” volcano orifice on either the Chromed second stages or any of the plastic derivatives like the later plastic Conshelf or similar second stages (the later Aquarius, Sea4, etc.). They all used the same “Inlet Fitting” with the fixed volcano orifice (part number 100444). Take a look at the first 5 diagrams. The later Titan, Cousteau, Calypso, Glacia, etc., all use the same basic downstream demand valve design (without the barrel body) and they all have adjustable volcano orifice. I tried to see if the 104106 inlet fitting could be used on the Chromed second stage, and does thread right on to it, but the plane where the volcano orifice operates is too far from the seat carrier. The interesting issue is that they continued to make the fixed volcano orifice until just recently. I thought that I have seen pictures of a new Conshelf XIV second stage with an adjustable orifice, but I either dreamed it, or it might have been a picture of a prototype. The diagrams (at least until 2014) all show it as a fixed orifice. Notice that the adjustable volcano orifice is the same part number (100128) on all the second stages below, but the inlet fitting changes depending on the model. Some of the cold water units (like the Glacia and the Arctic) have a lot more fins for heat transfer.
Fixed volcano orifice:
Adjustable volcano orifice.
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Post by nikeajax on Jul 8, 2020 11:05:17 GMT -8
So, how does one exactly go about adjusting one of these anyway?
JB
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Post by luis on Jul 8, 2020 11:59:38 GMT -8
If you have an "inline adjustment tool" you can adjust it in seconds by rotating out the volcano orifice until it starts to leak and then just screwing it back in just a tad. Without the tool you have to depressurize the LP hose (unless you have an inline LP valve), then disconnect the hose to turn the orifice a little-bit at a time until the spring force and the intermediate pressure are almost balanced. After every adjustment, it has to be pressurized to check. It sounds tedious, but with experience it is very quick. And a when you properly balance the spring force with the pneumatic force from the IP, then it takes very little effort (suction) to get a very simple design to work at its best. Pneumatically balanced second stages are seldom any better than a well designed and properly adjusted basic down-stream demand valve. When turning the volcano office it is important to press down on the purge button to avoid cutting the seat with the edge of the volcano orifice. Here are a couple of pictures of "inline adjustment tool".
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Post by nikeajax on Jul 8, 2020 12:19:08 GMT -8
Luis, excellent, thank you! Could you explain why this is necessary please: how is it different than using the adjusting nut for the lever? My Scubamaster has this feature and I'd really like to take advantage of it: JB
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Post by luis on Jul 8, 2020 12:33:02 GMT -8
The simple answer is: in this type of design the adjusting nut should only adjust the lever height.
When it gets complicated is that some technicians (and DIY owners) will adjust the lever until it is just touching the diaphragm. This reliefs the spring pressure (actually spring force) just slightly. In that situation the diaphragm itself is being used kind of like another spring to slightly counteract the valve closing force of the spring. This is not the best situation.
The big issue with doing that is that it doesn't take but a very slight indentation on the rubber seat for it to go out of tune and start leaking.
That is why it is best to separate the spring pressure adjustment and the lever height adjustment. In this type of regulator you adjust the spring force first and then adjust the lever height to just barely touch the diaphragm (without putting any pressure on it).
But if you don't have the independent ability to adjust the spring force then you try the next best thing. It is actually better to adjust the IP in that case to try to balance the spring force.
I should now clarify that in most "barrel-body down stream demand valves" (like the Scubapro 109) the adjustments are slightly different. The adjustable volcano orifice actually adjusts the lever height and the spring pressure is adjusted with the knob at the far end of the barrel.
I hope this is all clear.
Thanks
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Post by nikeajax on Jul 8, 2020 12:41:03 GMT -8
WOW--OK! I'm sure my friend Jim Steele has one of these for me to use...
Again, thanks for the info!
JB
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Post by luis on Jul 8, 2020 12:57:31 GMT -8
Interesting, the diagram you posted doesn't show the adjustable volcano orifice. But, I am not surprise that it was added in later models. That is why I am so surprised that Aqua Lung never did on the Conshelf second stages. BTW, you don't need the "inline adjustment tool". I did it for decades with out it and at time I still prefer not to use it (habit I guess). It does add a huge time saving factor for a good professional (getting paid by the hour). Wow, that is a very interesting weighted exhaust valve. That most have been an interesting attempt at overcoming the "case fault geometry" of a single hose. That is another separate subject, but a quick explanation can be found on my second post of this thread: vintagedoublehose.com/forum/viewtopic.php?f=26&t=10337&p=82571&hilit=case+fault#p82571
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Post by nikeajax on Jul 8, 2020 13:46:55 GMT -8
Interesting, the diagram you posted doesn't show the adjustable volcano orifice. But, I am not surprise that it was added in later models. Hmmmm, come to think of it, I haven't had it apart: that's an IDI second stage that I was assuming was exactly the same. Thanks for pointing that one out They both came from the HW Scuba Star-II:
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Post by vance on Jul 8, 2020 14:00:03 GMT -8
At risk of being repetitive, but because this kind of information is spread out all over the place, I'll say it again: some Sportsways single hose second stages have this adjustable seat. It's a nice feature, and unfortunately one that can't be easily modded to fit USD regs due to the different threads used at the regulator end. My fitting is the same thing, using the same hard seat/orifice and having the correct threads to fit USD.
I'd like to point out that calling it an adjustable orifice is incorrect and can cause confusion. The orifice is fixed in size. It is the hard seat that is adjustable. It moves in or out of a bore to adjust spring tension on the poppet. It is much like the second stage in a DAAM (and lots of other DH regs), but opposite. Instead of the second stage body being adjustable in or out to tighten or loosen, the seat moves in or out, accomplishing the same thing.
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Post by vance on Jul 8, 2020 14:12:40 GMT -8
I tried hard to use this idea in my DH conversions. The Dacor is lacking the meat to get a bore deep enough to utilize this feature. I would have like it to have an independent second stage unit that just screws down into the first stage body. Dang.
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Post by SeaRat on Jul 8, 2020 14:20:58 GMT -8
I have a SEA 4, and you have to be pretty careful with it as part #23 can easily break. I had that happen, and substituted the inner coffee filter of a K-Cup coffee pod for about a year. Something is necessary there or it could leak. I then ordered and got the part, which has the pin which keeps the front cover from rotating.
John
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Post by luis on Jul 8, 2020 14:23:53 GMT -8
At risk of being repetitive, but because this kind of information is spread out all over the place, I'll say it again: some Sportsways single hose second stages have this adjustable seat. It's a nice feature, and unfortunately one that can't be easily modded to fit USD regs due to the different threads used at the regulator end. My fitting is the same thing, using the same hard seat/orifice and having the correct threads to fit USD. I'd like to point out that calling it an adjustable orifice is incorrect and can cause confusion. The orifice is fixed in size. It is the hard seat that is adjustable. It moves in or out of a bore to adjust spring tension on the poppet. It is much like the second stage in a DAAM (and lots of other DH regs), but opposite. Instead of the second stage body being adjustable in or out to tighten or loosen, the seat moves in or out, accomplishing the same thing. Well, so you are going to tell me that we have been using the wrong terminology in the industry for the last 49 years. Sorry, but that is how long I have been working on these type of regulators. Now I am not even sure what you are calling the orifice. That is why we try to make it clear and I specifically call it the volcano orifice, because it does look like the top of a volcano (some say it also looks like a barnacle, but a barnacle is very irregular, more than a volcano). OK, The volcano orifice size is not adjustable (in size), but the matting surface (or matting plane) of the "volcano orifice" is adjustable "in and out" relative to the inlet body. The soft matting surface is what we normally call the soft seat, or for short just the seat. Let me say that I totally appreciate trying to use consistent and well descriptive terminology. After all the purpose of language is to be able to communicate a clear message across. Now a few disclaimers: English is not my first language, but it is my primary technical language. I went to college and received my engineering degrees in the continental US and all my CEU (Continuing education for my license) have always been in English. Now, engineers have a reputation for being poor spellers (I try hard to break that myth, sometimes successfully), but we all "try" hard to use correct industry-wise terminology. In any case if you understood what I was saying I hope my terminology was descriptive enough.
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Post by james1979 on Jul 8, 2020 14:26:09 GMT -8
Holy Crap! I step away for a few hours and Luis straight runs a school on this stuff! I'd like to point out that calling it an adjustable orifice is incorrect and can cause confusion. The orifice is fixed in size. It is the hard seat that is adjustable. It moves in or out of a bore to adjust spring tension on the poppet. It is much like the second stage in a DAAM (and lots of other DH regs), but opposite. Instead of the second stage body being adjustable in or out to tighten or loosen, the seat moves in or out, accomplishing the same thing. I shall now be known as an "orifice of adjustable position". This must be said in your best Monty Python voice... lol. Respectfully (and with humor), James
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Post by vance on Jul 8, 2020 14:40:48 GMT -8
OK, no offense meant, Luis. But you're saying just because you've been calling it an adjustable orifice for years, it must be correct.
It isn't correct. If the orifice was adjustable (bigger diameter to smaller diameter), you'd be able to open or restrict the opening of the volcano. You can't (with this part). That's all I'm saying. What you're talking about is adjusting the hard seat up or down in a bore to make more or less spring tension. It's an adjustable seat.
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