|
|
Post by crabbyjim on Mar 28, 2019 18:29:32 GMT -8
While Searat and the other cognoscetti are dissecting the subject of decanting multiple tank setups, I have been trying to figure out tilt valves. The design appears to be simple and robust so why was it abandonded?
|
|
|
|
Post by tomcatpc on Mar 28, 2019 20:02:05 GMT -8
Looking forward to the discussion on this. Guessing Jay will be by in the next few hours?
My extremely limited experience has been overall good. The one Healthways Scuba Star that had a tilt valve I have (I have since used the tilt valve part to complete my 1961 Scubair 300) took very little effort to rebuild.
I basically took the second stage apart, cleaned it and put it back together. It worked just fine, on dry land, have not dove it yet.
I guess finding parts would be the hard part if one were to rebuild one today? Esp. the hose with both male ends...but I think an adapter would work?
See what the more experienced members have to say, esp, the ones that actually have dived with a tilt valve.
Mark
|
|
|
|
Post by SeaRat on Mar 28, 2019 22:42:11 GMT -8
Okay, I'll bite. I went from a tilt valve Healthways Scuba Star (my second regulator) to an AMF Voit 40 Fathom regulator. This 40 Fathom regulator was the Voit equivalent to the USD original Calypso regulator. The claim was that because it was a balanced first stage, and downstream second stage, that the 40 Fathom/Calypso performed much better at depth. The advertising went so far as to say that if the hose came into the second stage at an angle (all tilt valves in the early 1960s did) that it was an inferior regulator. Then they advertised Hannes Keller's 800+ foot dive in a chamber in France and a bit later in a lake in Switzerland using the USD Calypso. That pretty much sealed the ad campaign, until Keller's next dive, which was a record breaking 1000 foot dive, but with two fatalities. By that time I had bought and was using the 40 Fathom regulator.  I think JB has insight into this from the Healthways and Dick Anderson perspectives. John PS, I also know that at about this time the USAF Pararescue teams went from the USD Mistral double hose regulator to their Calypso regulator. They skipped right over the tilt valves. PS2, Did you know that the Scott Full-Face mask Scuba was a tilt valve, and that it was fed but a HP line (I'm pretty sure)? |
|
|
|
Post by crabbyjim on Mar 29, 2019 6:08:20 GMT -8
So advertising led to the demise of the tilt valve? Is there anything inherently wrong with the design which was fixed by changing to the current design? I don't usually dive to 800 feet so I'm asking for a friend.
|
|
|
|
Post by technidiver on Mar 29, 2019 7:22:58 GMT -8
If I'm correct, the tilt valve gets harder to breathe at depth, and needs an OPV to vent the pressure if it's too high. I think the tilt Valve also can't tolerate higher pressures (3000 PSI). Jay's definitely the guy to ask about this!
TD
|
|
|
|
Post by tomcatpc on Mar 29, 2019 7:37:40 GMT -8
I have heard about it being harder to breath with a full pressure tank, but heard that great good at lower pressures. In the respect...I see how people would be swayed to the (now) more common downstream.
Having said that...if I found a reg that struck me in a way to buy it and restore it, I would not rule out passing it by just because it has a tilt-valve second stage. I can see the good side off them by nothing to adjust, etc. If the parts are all present and the rubber seal in the "needle/pin" valve is in good nick...there is very little to go wrong in the second stage.
Then there is the OPV, but as long as that works..
Looking forward to hearing Jay on this one!!
Mark
|
|
|
|
Post by tomcatpc on Mar 29, 2019 7:42:21 GMT -8
Off topic, but John brought up the Voit 40 Fathom. I have one and it was not the easiest (but not the most difficult either) reg to rebuild, but sure is a fun little reg to dive.
Mark
|
|
|
|
Post by nikeajax on Mar 29, 2019 8:07:17 GMT -8
OK boys, here's my two bits worth. It's not the high tank pressure per se, it's the required low-IP: because it's an up-stream-valve, higher IP's of around 120+ make them very difficult to breathe. Forget the industry standard of 135, because at that range there is a very noticeable lag, and inhalation effort climbs. They work best at around 95-100-psig. Then there's the positioning of the valve's nozzle: you can't direct them for efficiency: the air flow will always travel in the same direction of the needle-valve:  The can floods with air and you breathe from the can.  Now, look at the above down-stream-valve: there's a port in the valve body to direct the blast of air more efficiently. Yes, there are regulators such as the ScubaPro Pilot, which is an isanely complicated piece of machinery by comparison, or the Tekna 9200(?) which is very simple but also had it problems, but those tilt-valves have been augmented with more principals behind the redirection of air flow...  Jaybird |
|
|
|
Post by vance on Mar 29, 2019 9:01:51 GMT -8
The tilt valve is very simple, inexpensive to make, and are pretty bullet proof. They aren't the easiest breathing regs, and they aren't a good choice for dives over 60fow, I've heard.
The modern day problems with a tilt valve are finding a replacement seat and subbing in a diaphragm. Also, as Mark said, the hose fitting on the reg end is different than the normal hoses, so replacements would be problematic. If the diaphragm's height doesn't match the length of the seat needle, it will require modifying (like adding on or cutting the needle).
I have a Little Gem that I'm trying to get working with a generic diaphragm. It leaks due to just a bit too much contact between the diaphragm plate and end of the needle. I'm reluctant to bend it or cut it. If it were possible to add a spacer under the diaphragm, it would help, but the case ring is too narrow to accommodate one. I had to thin the sealing surface on the diaphragm to get the ring on....
|
|
|
|
Post by nikeajax on Mar 29, 2019 9:47:00 GMT -8
The problem with the the 1030 Calypso was that the LP-valve orifice wasn't a volcano, but a flat surface that the poppet disk sat against: you can't get very high pressures, and I think the maximum was about 110-psig. Much higher than that and it can't hold pressure. The next can style (sorry but I don't remember the model number) had an actual volcano orifice, sharp edge, to take advantage of the less mechanical effort of a wedge shape's (sorry if I'm not using the exact terminologies) in order to seal up the valve. Here's what I'm talking about: en.wikipedia.org/wiki/WedgeJaybird |
|
|
|
Post by crabbyjim on Mar 29, 2019 10:49:12 GMT -8
Thanks JB, your pictures of the downstream valve below the tilt valve plus your explanation of directed air have cleared up up a lot for me. Thanks to all of the contributors to this forum I am beginning to understand how this equipment works. Now it’s off to the pool to test my rebuilt (by me) Calypso IV.
|
|
|
|
Post by SeaRat on Mar 29, 2019 12:04:14 GMT -8
The problem with the the 1030 Calypso was that the LP-valve orifice wasn't a volcano, but a flat surface that the poppet disk sat against: you can't get very high pressures, and I think the maximum was about 110-psig. Much higher than that and it can't hold pressure. The next can style (sorry but I don't remember the model number) had an actual volcano orifice, sharp edge, to take advantage of the less mechanical effort of a wedge shape's (sorry if I'm not using the exact terminologies) in order to seal up the valve. Here's what I'm talking about: en.wikipedia.org/wiki/WedgeJaybird JB, I'll have to check on that orifice situation, but I do know that the reason the U.S. Navy did not approve the original Calypso had nothing to do with the inhalation resistance, but rather the exhalation resistance through that very small exhalation valve in the diaphragm. They did not get it right USD) until the Calypso III for the Navy. We in the USAF ignored the Navy, and bought the original Calypso. The problems with breathing resistance at depth for the tilt valve was definitely its design. You cand get pretty good results with a tilt valve by replacing its diaphragm with a silicone one,bwhich I have done on my Sportsways Sport Diver. But on hard inhalation with the improved diaphragm the air is wasted through the exhaust (blow by). John |
|
|
|
Post by nikeajax on Mar 29, 2019 12:36:12 GMT -8
I'll have to check on that orifice situation, but I do know that the reason the U.S. Navy did not approve the original Calypso had nothing to do with the inhalation resistance, but rather the exhalation resistance through that very small exhalation valve in the diaphragm... John John, you are/that is correct. The lower IP effects very little, I was just pointing it out as a comparison of the two: I should have stated this, but once again, I'm working on very little sleep  If you compare the exhausts of an early DH and an early SH, you'll see a very radical difference: the DH's exhaust will be noticeably larger: this would be the reason why the USN didn't like any of the early SH's. A project I'm still working on, the paint chips too easily, is a Scubair/Scuba Star with a blown exhaust:   I seem to recall it uses a 28mm mushroom, and when I tried it, it was like a night and day difference between the 20mm. Please note that I usually put a 23mm on these old regs, but a 20mm will work just as good... JB |
|
|
|
Post by nikeajax on Mar 29, 2019 12:48:58 GMT -8
Here's a visual for you for exhausts:   Yes, the USD/Voit and Dacor used duckbills, but they allowed a very good vent for escaping gases too But hopefully you can see how much bigger it is on a DH? JB |
|
|
|
Post by snark3 on Mar 29, 2019 14:10:02 GMT -8
I just pulled out my Snark II, checked the manual and confirmed its a tilt valve. I hooked it up to a tank and it works, but its hard to exhale. I assume some of the rubber parts need to be replaced. I may need to move this up on my project list. It'll be a new learning experience.
|
|
