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Post by SeaRat on Jul 12, 2005 21:40:05 GMT -8
This thread is a bit different, in that I want to finally capture some of the design limitations and modifications that have been made, both by the manufacturers and by the vintage divers who swim around on this site. There is a lot of expertise here, and there are some things people should know about vintage regulators and scuba systems that are not generally know or discussed.
I will begin by proposing a format, and showing an example. The format is to put the name of the regulator or scuba in the subject line (you have to use the "Reply" button, and not the quick posting method, to do this), then discuss it in the message text. In the message text, state the design problem with the regulator, then the engineering solution.
One note of caution. I will say what I have done with my regulators, but each person is individually responsible for their own regulators, and any modifications made must be the sole responsibility of the person making the modifications. I do not recommend that anyone follow my lead on any of these modifications. I present them as engineering problems only, as each of these devices has its own limitations.
John
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Post by SeaRat on Jul 12, 2005 21:57:09 GMT -8
Engineering Problems
The Trieste II was a very advanced design, which never got off the ground. It did not become a popular regulator, and did not displace the DA Aquamaster or Royal Aquamaster from that spot as the most visible two-hose regulator around. It did provide some things that the DA Aquamaster and Royal Aquamaster did not, including the ability to put a "J" reserve on the regulator, HP and LP ports, and a compact style. Design limitations were its downfall though, and here are the ones I have identified:
--Diaphragm with a built-in "set" which caused higher than necessary breathing resistance.
--A poorly designed venturi system, which sent too much air into the case, and not enough down the intake hose.
--A second stage valve housing (Item 21, the LP seat holder) that had a set screw in the body which did not hold it in the ideal position, pointed directly down the intake hose.
--No LP outlet for the left side of the regulator.
Engineering solutions
--Built a new diaphragm out of rubberized fabric, without any resistence to movement.
--Blocked off one of the small holes in the second stage valve holder.
--Checked position of the second stage valve holder before closing the regulator.
--Used an extended LP adaptor with four outlets to clear the bottom of the regulator, and allow a hose to go over my left shoulder.
--Fine-tuned the LP seat holder by unscrewing it and testing it to ensure optimum position position at recommended interstage pressure.
--Because of the better venturi, I placed a mouthpiece baffle in the mouthpiece to keep air from "blowing by" the mouthpiece and being exhausted. This effectively routed it into the mouthpiece. I used the baffle out of a Healthways SCUBA regulator's mouthpiece system, and glued it in place.*
John
*Please note that on one dive, this became displaced, and cause momentary loss of breathing air when it backed up against the inhalation valve. I switched to my octopus, and continued the dive. I have since re-glued it in place, and continue to use it.
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Post by nemrod on Jul 13, 2005 0:27:28 GMT -8
The engineering problems with the Aquamasters and Mistrals are to numerous for me to address. The biggest one that impacts us in the "modern" world is:
1. Lack of LP and HP ports and provision for an SPG.
2. Neoprene rubber diaphram, mushroom valves and duckbill, tends to be stiff and takes a set greatly reducing performance, responsiveness and increasing effort
3. The brass cases are easily damaged
4. No way to get inside the bugger if it has those darn clips to adjust and clean after a dive.
What I have done about it:
1. Installed a LP adpter from Bryan, installed a banjo fitting for SPG
2. I picked over several diaphrams to get the softest and most flexible ones and I treat them with silicone. I installed silicone mushroom valves from Vintage Scuba and aquired several NOS USD duckbills that are very thin and flexible.
3. Not much to do here but I wish for stainless
4. Have aquired one retainer ring and will buy several more from Bryan when he gets them in.
Additionally I have finely tuned my Royal Round label and my Mistral by feel and touch using the manual only as a guide. Pool tested and then tuned some more. The Royal breaths on it's on free flowing at the slightest pressure displacement.
Bryan tuned my other square label Royal and my nice DA and they both do fine so I have not messed with them--yet!
The orientation of the hookah port is not ideal so I have been fooling around with stub hose and a three way splitter. The darn thing hits the manifold on doubles as well and that is an annoyance.
I have no doubt that my round label Royal is sufficient and adequate to undertake any sport diving mission. James
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Post by Broxton Carol on Jul 13, 2005 2:00:43 GMT -8
Your right about the drawbacks of old parts getting set and stiff, and soft brass etc, BUT just think of the fun your having. When I hit the water, I could care less if my reg is showing a little wear. Im not so young myself anymore! Like Jackie Gleason used to say.............. :-"And awaaaaaay we go"! And suddenly Im young again. Cheap thrills!  |
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US Divers DX AQUALUNG
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Post by US Divers DX AQUALUNG on Jul 13, 2005 19:46:29 GMT -8
This was US Divers Company's first attempt at a single stage regulator. The Mistral evolved from this regulator, which was manufactured from before 1955 (it is included in Rick and Barbara Courier's book, dive, the complete book of skin diving, published in 1955 by Wilfred Funk, Inc. If you do not have a copy of this book, it would be one well worth the effort of finding. Anyway, this was a very easy breathing regulator compared to the DA Aqualung, which was the two stage higher-end regulator of the time. It has a metal mouthpiece, and a small venturi tube within the inhalation hose that pipes venturi air directly to the mouthpiece. I got one used in the 1970s, and decided to revamp it because it did have several problems. Engineering Problems--The hoses on this regulator were indestructable, and I still have them. But they were only 19 inches long, and not stretchable. I had to wear it directly behind my neck in order to be comfortable with this regulator. --The yolk would not fit new valves. It was the old style manufactured at the Broxton Avenue location. --Corrosion on the top and bottom boxes. Engineering solutions--I changed the hoses to hoses made for fire department SCBAs, which were much longer (28 inches). I had to replace the inner tubing with a newer tubing, which I attached with electrical ties. --The yolk was changed to a newer style, one which allowed the use of a HP Banjo Fitting. --This regulator was not in good shape when I received it, so I had the bottom and top boxes sent out to be chromed. The top box did not take the finish too well, so I switched with a Mistral top box that I also had chromed. DiscussionWhat I ended up with is a very nice regulator, although I really wish I hadn't chromed over the name plate. I can use a SPG with this regulator, and the long hoses work because of the interior hose, which provides very little friction even though it is longer by 9 inches. The regulator can be worn lower because of the hose length too, which also improves breathing. To explain this, let me quote Fred Roberts: [/B], without the gush of air. This has been achieved by placing primary and secondary holes in the orifice (18), Figure 3-5. The orifice of the Mistral is aimed down the inlet hose. Primary air rushes down the intake hose drawing second chanmber air with it. In the DX and DW this action had caused a rapid depression of the low pressure diaphragm (28) and thus the gush. Note that in the Mistral the air also escapes through secondary holes at the side of the orifice. THis secondary air flows along the inner walls of the box and fills in the void left by the air sucked down the intake. In doing this, it acts as a damper on the movement of the diaphragm (28) and keep it from a violent response. Roberts, Fred, Basic Scuba, Self-Contained Underwater Breathing Apparatus, Second Edition,D. Van Nostrand Company, Inc., Princeton, New Jersey, 1963, pgs 180-181 (emphasis added)[/Quote] The metal mouthpiece has the attachment for the inner hose, and a disc which is supposed to support a non-return valve on the intake side. I have eliminated the non-return valve (it's no longer available, and of a different type than any now produced), but retained the metal disc. This disc blocks a lot of secondary air from coming up, and allows it through two slits only. I think this, combined with the additional length of the hose, counters somewhat the "gush" Mr. Roberts discusses above. I did put a "Caution" label on the regulator that states, "Caution--No Non-returns." This regulator is much quieter than the Mistral when breathing, as most of the air goes up the inner tube. This is also a plus for fish observation, along with the lower position on the diver's back. Here's a photo of the regulator in use last year:  John |
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Post by SeaRat on Jul 14, 2005 20:02:06 GMT -8
Well, I forgot to sign in on the above post, so the subject line was messed up a bit. Anyway, here's another photo of me using the USD Aqua-Lung DX regulator.  Yes, I know it's pretty ugly, but it does also show the Dacor Professional vintage mask I was using that day. John |
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Post by Deleted on Jul 15, 2005 9:21:39 GMT -8
John
Interesting thread on this req. I've comtemplated a ridge mouthpiece assembly for my RAM, but can't find anything yet that beats the original.
Anyhow, I wonder how do you see out of that mask, can't even see your eyes.
I am nearsighted, have been since the 3rd grade back in the last century. I have gone thru many a different mask, from the old Vido to the Pinoccio Delux which all sported prec. lens so I could see.......now I wear soft lens in my eyes and use the old style oval or oblong masks that have absolutely nothing between my eyes and the lens, not even a purge or nose pocket. It's like a plate glass window into the sea.
Michael
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Post by SeaRat on Aug 12, 2005 9:51:28 GMT -8
I just replied to a different thread (in the buying equipment section), concerning the Snark III. Here's what I said concerning the Snark III thread:
John
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