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Post by sea.explorer on Jun 7, 2005 7:44:46 GMT -8
I am looking for answers to a mystery I have been trying to solve for some time. I have a Royal Aqua Master that is without a doubt the best performing RAM that I and several others have ever found. It is a total anomaly. When hooked to a manahelic gage this reg has a cracking pressure of less than 1/2 and inch! the vast majority of the Royals I have encountered crack consistently at about 1". If you have one that comes close to or betters .5" let me know. This difference is definitely noticeable when diving the regulator. To get to the bottom of this I took two RAM. I fully cleaned both regulators and installed brand new parts kits from Bryan which include all new springs, LP seat, washers, HP diaphragm, and I put in a brand new Teflon HP seat and a new filter. I then reassembled both regs and set the IP exactly the same on both regs. I even used the same diaphragm in both regs with the horseshoe adjusted the same. And still the one cracks at >.5" and the other just under 1"? Can anyone think of a cause for the variation? If we can figure out the answer and duplicate the performance of the mystery Royal then everyone can have the perfect RAM This reg performs equal to or better than even high end single hose regs but I can't duplicate it. Thanks for the help. -Ryan
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Post by SeaRat on Jun 7, 2005 9:08:38 GMT -8
I have a Trieste II that cracks at about 1/2 inch water too, and I had to work to do it. Here are some points to check:
--The LP diaphragm--make sure that it is well treated with silicone (but not on the sealing surface), so that it is as flexible as possible. On my Trieste II, the original diaphragm was so stiff that it contributed to over 1" of suction effort.
--The inhalation side mushroom valve in the mouthpiece could increase the suction effort if it is at all inflexible. Switch to silicone if possible, or treat the neoprene valve with silicone grease (rub it in, let it sit overnight, then wipe it off as completely as possible).
--Check the height of the demand lever. If the horseshoe is a bit lower, it will affect the suction effort by requiring the diaphragm to be depressed slightly further, which decreases the flexibility of the diaphragm because of the stretching.
--There is more to the balance between the interstage pressure and the spring pressure on the LP seat than just setting the interstage pressure. If the spring is slightly stiffer on one than on the other regulator, that can definately affect the cracking effort. I'm trying to remember whether the LP seat holder (DA Aquamaster terminology) screws in, and looking at the diagram, it seems that it does. It has three outlet holes, and I think this is the same for the RAM. You need to balance the seat by ensuring that the seat holder is screwed out as far as possible without leaking. Here, a 1/3 turn can make a difference in the cracking effort. Rather than simply screwing the seat holder into the body, and leaving it, you can adjust it (I think). To do this, screw it in, then ensure it seals against the interstage pressure. Now, release the interstage pressure, and screw it out 1/3 turn. Reapply the interstage pressure and ensure it seals. Remove the pressure, and screw it out 1/3 more turn, then reapply to ensure it seals. You will get to a point where there is a slight leak. When you do, screw it back in 1/3 turn until the leaking stops. You have now manually balanced the spring force against the interstage pressure (which is done on some single-hose regulators at the second stage by an adjusting screw; Scubapro started that in the 1970s). But it can be done on other regulators, specifically the Royal Aquamaster, with very pleasing results.
Good luck,
John
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Post by nemrod on Jun 7, 2005 9:48:07 GMT -8
I have a round lable and a square label. Of the two the round label is the smoother and easier breahing. I always assumed it was just because it was more finely adjusted. Both are very easy breathing and I m certain that my round label is in the .5 range and the other not far behind. I used NOS duckbills, new silicone cage valves, my two best diaphrams etc. The silicone valves do make a difference. Clearly a super flexible silicone diaphram would help a bunch, too bad none exist. James
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Post by sea.explorer on Jun 7, 2005 10:56:22 GMT -8
I have a Trieste II that cracks at about 1/2 inch water too, and I had to work to do it. Here are some points to check: --The LP diaphragm--make sure that it is well treated with silicone (but not on the sealing surface), so that it is as flexible as possible. On my Trieste II, the original diaphragm was so stiff that it contributed to over 1" of suction effort. I put the same diaphragm in both regs so I don't think this is the answer. The flexibility of the diaphragm is certainly a factor. --The inhalation side mushroom valve in the mouthpiece could increase the suction effort if it is at all inflexible. Switch to silicone if possible, or treat the neoprene valve with silicone grease (rub it in, let it sit overnight, then wipe it off as completely as possible). This is also true but I tested the regs directly from the box in order to eliminate this variable. --Check the height of the demand lever. If the horseshoe is a bit lower, it will affect the suction effort by requiring the diaphragm to be depressed slightly further, which decreases the flexibility of the diaphragm because of the stretching. I adjusted the horseshoe to the same height on both and used the same diaphragm in the same orientation on both. --There is more to the balance between the interstage pressure and the spring pressure on the LP seat than just setting the interstage pressure. If the spring is slightly stiffer on one than on the other regulator, that can definitely affect the cracking effort. I'm trying to remember whether the LP seat holder (DA Aqua master terminology) screws in, and looking at the diagram, it seems that it does. It has three outlet holes, and I think this is the same for the RAM. You need to balance the seat by ensuring that the seat holder is screwed out as far as possible without leaking. Here, a 1/3 turn can make a difference in the cracking effort. Rather than simply screwing the seat holder into the body, and leaving it, you can adjust it (I think). To do this, screw it in, then ensure it seals against the interstage pressure. Now, release the interstage pressure, and screw it out 1/3 turn. Reapply the interstage pressure and ensure it seals. Remove the pressure, and screw it out 1/3 more turn, then reapply to ensure it seals. You will get to a point where there is a slight leak. When you do, screw it back in 1/3 turn until the leaking stops. You have now manually balanced the spring force against the interstage pressure (which is done on some single-hose regulators at the second stage by an adjusting screw; Scubapro started that in the 1970s). But it can be done on other regulators, specifically the Royal Aquamaster, with very pleasing results. I used new springs from the same run so there may be a slight difference but it should be minimal. I like the idea of manually balancing the spring force against the interstage pressure. i can see where that could make a significant difference. I will try that tonight. Thanks for your thoughtful analysis. "The silicone valves do make a difference. Clearly a super flexible silicone diaphragm would help a bunch, too bad none exist. James" I agree -Ryan
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JohnA
Pro Diver
Posts: 134
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Post by JohnA on Jun 7, 2005 12:48:54 GMT -8
I don’t know if this will help, but it may give you something to look for. Although I have taken apart my RAM (round label) I would not consider myself anywhere near an expert but here is my example that may help.
When I was doing a lot of tech diving I started switching my regulators from Scubapro to Apeks (I still use my Apeks and love them). I got a great deal on a pair of T20/DS4 regulators and was under the assumption (so was the dive shop) that the T20 second stage was identical to the TX50, only lacking the adjuster and metal heat sink. So I buy a couple of adjuster kits and convert them to an adjustable 2nd stage, and guess what, they breath no where near as good as a TX50, I check the parts schematic and all the internal parts are the same, numbers and everything. I was thinking the same thing, must be a spring or a rubber part that is causing the problem so I switch out a couple of springs but still nothing. I was stumped. Then I speak to a tech up in cave country that had the same problem. He found that the Shuttle valve which is in essence is the lp seat that sits inside the spring in the second stage and what the adjuster sits against was longer in the T20 than in the TX50. Although the same part number, when they came from the factory the T20 had a tip on the shuttle valve that extended it about an 1/8 of an inch. Once I remove that “tip” the T20 breathed like a champ (I actually have to de-tune it during the dive)!!
Now, what does the adjustment of an Apeks regulator have to do with why a RAM breaths better than another. Is there a part inside the lp side of the RAM that acts much the same as the Apeks shuttle valve? Could that “pin” be just a hair shorter (or longer) and therefore causing the RAM to breath considerably better? Hope this helps.
John
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Post by Bryan on Jun 7, 2005 13:04:41 GMT -8
You have a good point on the LP seat height. When I 1st started reproducing the rebuild kits I had the LP seats cut from rubber cord stock. There was a slight variance in thickness and a few even had a bit of lateral deflection to them. Shortly after that I had all seats molded as opposed to being cut from stock. The mold was very expensive but the quality and tolerances were much much closer. Tom Madere brought to my attention that the LP stem itself comes in two different lengths..... John, the Trieste service info describes the adjustment on the LP seat holder you are talking about, but I have never seen it described or recommended in any USD literature. They work in a similar fashion so I don't see why it would not work ......But as Ryan said, since it is not in the USD literature it would have to be considered experimental...So I am in no way implying that anyone should try it!!
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Post by SeaRat on Jun 7, 2005 14:42:49 GMT -8
Bryan,
Adjusting the LP seat holder is actually the same result as adjusting the interstage pressure. Both compensate for the differences intrinsic to different springs/holder combinations. I mentioned this as a possible way of doing it because you mentioned that you wanted the interstage pressure to be the same for the two regulators. This is a harder way of doing it, but accumplishes the same mission. The advantage is if you are running another second stage off the RAM as an octopus, you can keep the interstage pressure the same.
Concerning this being "experimental," it is, and I don't recommend anyone do this if they are not very experienced in regulator maintenance. But when you conside it, even regular service of the RAM is "experimental," as this regulator has been discontinued since the 1980s, and no one in Aqualung will stand behind anything we do concerning them. That goes for replacing seats with those you have had made for this purpose, but are not made by Aqualung.
John
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Post by Bryan on Jun 7, 2005 15:29:26 GMT -8
I don't consider following the service procedures given by US Divers to be "experimental". If that was the case I doubt they would have published them to begin with.
The 2nd stage seats are reproduced by a rubber company that 1st did an analysis of 9 brand new LP seats from US Divers double hoses that I provided them. The size and durometer is exact to the original. I do not consider an exact duplication of the original part to be an experiment either.
By "interstage pressure" are you talking about the "intermediate stage pressure" ? I am unable to find interstage pressure in any manual that I have.
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Post by SeaRat on Jun 7, 2005 16:34:18 GMT -8
Bryan,
I was not at home looking at the manual when I wrote the above. While I agree with you, were there to be something happen, I doubt that Aqualung would stand behind the use of seats and other replacement parts for any of these regulators. I am using a SCBA hoses, for instance, on my USD Overpressure Breathing single stage regulator, the DX model. The original hoses, made in the early 1950s, were too short for my purposes. But I don't expect USD (now Aqualung) or the SCBA manufacturer to stand behind these products for the uses I am putting them to. That is why I used the term "experimental," which you also used above concerning the procedure I discussed. I consider that all regulators have some compromises, and that to better understand these you need to "experiment" with them. I do this knowing that this is my responsibility alone, and that if there is a problem with my "experiment," it is mine alone. I cannot go back on the manufacturer for equipment that has been obsoleted, and is now unsupported. Does that mean we shouldn't use these regulators? Heck no, as they are still very good pieces of equipment if taken care of. But the responsibility for that is ours alone.
Yes, I was talking about "intermediate stage pressure" when I said "interstage pressure." Interstage means between the two stages, and I think is used by some (even if not in the literature from USD).
For anyone reading this, I do think Bryan's seats are as good as new originals, and I will probably be buying some from him within a year. It is certainly better to replace them than to use 40 year old materials.
'Hope this helps.
John
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Post by Captain on Jun 7, 2005 17:19:03 GMT -8
I would try switching the LP seat springs and see if the lower cracking effort also switches to the other regulator. To carry this further you could switch one part at a time and see what changes in cracking effort take place. I would bet that the Lp seat on the easier one is weaker. Of course you could compensate for this by increasing IP on the stronger spring. Being the RAM has a balanced first stage the IP could be set higher than an AquaMaster would tolerate because the IP would not increase at low tank psi which could cause free flow. Also Bryan said I had found different LP stem lengths but it was different hight horseshoe supports that I came across and the possibility the higher support would put the horseshoe closer to the diaphragm which could have some effect.
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Deleted
Deleted Member
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Post by Deleted on Jun 7, 2005 18:48:33 GMT -8
Searat/Bryan and the rest of you guys.....
This thread and the previous one on overbreathing has me asking a couple of questions I've been wondering about since I had my RAM rebuilt. I'm not up on the mechanics, pressure theory of the 2 stage, other than what I've read on the reprints Bryan has on his website.
The IP pressure,,, I see where the USD Mentor IP is 135, on the USD commerical reg's, DA, RAM etc, the IP is 110 (recommended) and if I remember correctly, mine, after rebuild was set at 125........why are the IP's so low, and not as the single hoses and the Mentor, 135 psi? What advantage/disadvantage is there with 110 vs 125 or 135 psi? I suspect the earlier models had a reason, but seems the RAM, with the 1st stage componets similar to the conshelf 1st stage can manage the higher IP......or am I mistaken?
Secondly, I've hooked up an old Sportsways second stage as an octopus and a hose for my Z90 off the LP port. Is 125 IP going to be enough to operate everything?
I've just finished connecting everything and waiting for the paint to dry on my doubles to try everything out in the pool. The plan is if this system breathes anywhere close to the conshelf supreme I bought my wife, or well enough for her as a new diver, I'm making up a second system for her with the round lable I have waiting on rebuild.
If there is potential problems with what I'm doing, ie: not enough IP to operate everything, I sure would like to know.
Michael
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Post by sea.explorer on Jun 7, 2005 19:20:54 GMT -8
This has been very interesting. When I got home today I tried the adjustment of the spring tension as discussed. It made a big difference and I was able to reduce the cracking pressure on both regs and now they are performing equally. A note from my tests:
When I backed off the spring tension as discussed the point at which it leaked and I the took it back the 1/3 turn the hex portion of the second stage Assembly no longer locked into the notches on the horseshoe lever supports. This allowed the second stage assembly to turn freely. I decided to only back off the spring tension far enough so that the notches still engaged the hex nut at least 50%. It is more secure this way and it still drooped the cracking pressure about .4" I think that this solution is the best compromise. The same thing could be accomplished it seems with a weaker spring but it is easier to adjust the spring tension than find a weaker spring. These adjustments combined with carefully adjusting the lever height made the significant difference. With a flexible silicone diaphragm it would be near perfect. I will get to dive with the regs in two weeks and I will report back to the group. I thank everyone who has contributed so far. This has been most interesting for me. Thanks -Ryan
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Post by Captain on Jun 7, 2005 20:04:42 GMT -8
As in all mass produced machanical things there is a phenomenon known as tolerance stack. Every part is designed with a + or - so much tolerance. Most finished products end up with an average mixture of + and - parts and preform within design limits. By random chance some items end up with more + tolarence parts than - parts and some end up with more - parts than + parts. Depending on how the excess number of + or - parts affect the preformance of the finished item one item could preform at better than designed preformance and another could preform worse than design. This in it self could explain how two identical regulators could preform totally different.
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Post by SeaRat on Jun 7, 2005 20:06:41 GMT -8
Ryan,
'Glad this worked for you. I thought it would, and haven't done it since about the late 1980s.
Michael,
I went back and found my notes from the US Navy School for Underwater Swimmers in Key West, Florida, where I took their course in May and June of 1967. I could not find any references to the regulator tuning, but did find a couple that others may be interested in:
I could go on, but that's the core info I wanted to produce here. Why is it important? Well, we put the regulators on the full cylinders to set the pressure to 110 psi +-5 psi on a full cylinder. I had thought that was 3000 psi, which is what the Navy Diving Manual states, but most probably it was 2150 psi. This would mean that they filled both their steel and aluminum cylinders to the same pressure. If you set a DA Aquamaster to an intermediate stage pressure of 110 psi at full, and the full is 3000 psi, it will register about 140-145 psi at 500 psi tank pressure. This is because of the unbalanced nature of the first stage.
Now, let's discuss the Royal Aquamaster. It has a balanced first stage. That, to me, would mean that an intermediate stage pressure of about 140 psi would be what I would want to see.
Now, why would someone deliberately not want the optimum intemediate stage pressure for this regulator? Well, there are a few assumptions concerning this.
First, if the intermediate pressure is lower, the seat will seat itself more positively, and there will be fewer complaints of air leakage due to some slight bit of "stuff" getting on the seat during use.
Second, and this has been discussed elsewhere, there is always the potential in some positions for the water pressure difference between the exhaust valve and the center of the diaphragm will be more than the cracking pressure at the demand valve. If this is greater than the cracking effort, the regulator will leak.
How can this happen? Well, some of the duckbill valves are shorter than the originals, and do not overlap to the center of the regulator's diaphragm. If they are short, and the cracking effort is say 1/2 inch, but the distance of the duckbill from the center of the diaphragm is 1 inch, then there will be a leak is some positions in the water (I have photographs of this on another thread at this site).
So technicians and the USD recommendations are for an intermediate stage pressure that is provides a cracking effort of over 1 inch so that this would be less likely to occur (my thesis only, no info from the manufactures or the Navy on this one, although the Cousteau patent itself does mention this). I have one other theory about this, and that is that the manufacturers (Dacor, USD, AMF Voit, etc.) were really not trying very hard to manufacture the best performance for their double hose regulators. I gave Dacor information about improving the lever system on the R4 and never heard from them again--even gave them my regulator, which they lost and finally replaced with a Beta-test Pacer regulator. Again, this is my theory, but they were probably trying to make the double hose regulator look like a poorer performer than the single hose regulator, as they were actively promoting the single hose regs during this period. Remember, it took something like 15 years for the single hose regulator to beat US Navy standards and become better than the DA Aquamaster. There is one other thing, and that is that I know many of the US Navy divers who serviced their own regulators always "tweeked" them for their finest performance, no matter what the manual said.
Concerning the Sportsways regulator off the Z90, I have no experience with the Z90. I can say that you should hook them up, and try them out in a pool or open water to see how it works, and if it doesn't work well, make adjustments. Be aware that some DIR divers deliberately de-tune their octopus regulators so that they won't free flow. Lower IP won't cause a malfunction, but can make it more difficult to breath in an emergency situation. My thought is the opposite--I like both regs to function similarly, so I designed my BC to have a special pocket that I can put my octopus into with the mouthpiece down so it doesn't free flow. I also have begun using a Dacor Pacer regulator for my octopus, as it positively will not free flow over 4 seconds (due to its unique design).
Again, I hope this helps.
John
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Post by Bryan on Jun 8, 2005 5:39:27 GMT -8
Bear in mind that the double hose regulator was never designed to run a Safe 2nd stage/Octopus, LP inflator etc etc. So IMO you will have to decide if the performance of the additional devices is acceptable to you. Simply lowering or raising the IP pressure would not necessarily improve the performance of the other devices either. There are clear guidelines that establish the baseline for regulator adjustment and performance. Beyond that you have to rely on knowledge, experience and some degree of experimentation for optimal performance.
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