Looking for info on limitations
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2airishuman
Contributor
I have several Conshelf regs including two sealed with the silicone fluid, one of them "external fine adjust" and the other not. I've seen photos of the dry kit but haven't had one in my hand. All of these configurations are very similar: The environmental chamber replaces the cone that holds the main diaphragm spring, adding a secondary diaphragm where the threaded IP adjusting cap usually is. The dry kit has a plastic piece that transfers pressure from the main diaphragm to the secondary. The silicone fluid ones just use the inert fluid to transfer pressure. They all work fine, the only difference being that the silicone fluid is messy during service.
I totally agree that the only difference is the silicone fluid, but IMHO that is a huge difference. The second diaphragm ring can be just hand tighten and I can adjust the IP at any moment without any mess or losing any fluid. Locating some replacement silicone fluid has not always been easy for some. And I personally just hate the mess… but that is just me.
All my Conshelf and my wife Conshelf and Titan have dry environmental caps.
Here is one for sale (with pictures of the dry environmental cap) :
Vintage Double Hose • View topic - US Divers Conshelf XIV with extras
Here are pictures:
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This is the best bailout regulator for hardhad work, never had a problem with mine and it has been through some nasty stuff.
Luis,I totally agree that the only difference is the silicone fluid, but IMHO that is a huge difference. The second diaphragm ring can be just hand tighten and I can adjust the IP at any moment without any mess or losing any fluid. Locating some replacement silicone fluid has not always been easy for some. And I personally just hate the mess… but that is just me.
All my Conshelf and my wife Conshelf and Titan have dry environmental caps.
Here is one for sale (with pictures of the dry environmental cap) :
Vintage Double Hose • View topic - US Divers Conshelf XIV with extras
Here are pictures:
I am curious now, as the dry environmental cap probably has some mechanism to transmit the pressure to the main diaphragm; is that the secondary diaphragm? My curiosity is because I have the Sherwood Magnum Blizzard, a 1980s regulator that is a piston first stage, but with an environmental seal to keep water out. They use a very slow pressurization that bleeds off into the water. I know that the silicone sealant is a fluid, and it transmits the pressure differential with depth directly to the diaphragm, but what happens engineering-wise with the dry cap? How is the pressure transmitted to the diaphragm?
SeaRat
2airishuman
Contributor
The one in my HOG D1 is just a plastic disc with a post on it. The disc faces the secondary (environmental) diaphragm, the post pushes on the main diaphragm.
I'll be taking a pair of the XIV regs down to around 200ft for a few dozen dives in the coming weeks on independent doubles.
As already demonstrated the world over and with decades of testing they are a solid reg.
All the best,
Cameron
As already demonstrated the world over and with decades of testing they are a solid reg.
All the best,
Cameron
As described by 2airishuman, the dry environmental seal is just a push rod with a disk that transmits the ambient pressure to the HP diaphragm. It is very simple, but it has to be properly designed.
If the effective area (as in effective pressure area) of the outer diaphragm disc combination is the same as the effective area of the inner diaphragm, the IP will increase by directly following the ambient pressure increase.
If the effective areas are different (outer effective area is bigger) then you marketing department can call it an overbalanced first stage (total incorrect terminology) and as accompany you can charge more. Then you claim that the IP will increase at a higher rate than the ambient pressure so it will breath better at depth. The funny thing is that in order to avoid free flow at depth, you have to pair up with pneumatically balanced second stages that are affected less by IP change. Nice marketing …
Note: you may notice I use the term “effective area”. The pressure effective area is a function of the actual area, the diaphragm stiffness, and the edge clamping. In other words, a stiff diaphragm with a stiff perimeter clamping support will not react (with the same effective area) to pressure like a soft diaphragm that will flex all the way to the edge.
The Conshelf/ Titan dry chamber transmits the ambient pressure at a ratio of 1:1 to the IP. I have measured to just under 100 feet of depth and the IP was always constant.
If the effective area (as in effective pressure area) of the outer diaphragm disc combination is the same as the effective area of the inner diaphragm, the IP will increase by directly following the ambient pressure increase.
If the effective areas are different (outer effective area is bigger) then you marketing department can call it an overbalanced first stage (total incorrect terminology) and as accompany you can charge more. Then you claim that the IP will increase at a higher rate than the ambient pressure so it will breath better at depth. The funny thing is that in order to avoid free flow at depth, you have to pair up with pneumatically balanced second stages that are affected less by IP change. Nice marketing …
Note: you may notice I use the term “effective area”. The pressure effective area is a function of the actual area, the diaphragm stiffness, and the edge clamping. In other words, a stiff diaphragm with a stiff perimeter clamping support will not react (with the same effective area) to pressure like a soft diaphragm that will flex all the way to the edge.
The Conshelf/ Titan dry chamber transmits the ambient pressure at a ratio of 1:1 to the IP. I have measured to just under 100 feet of depth and the IP was always constant.
Checking back in. As expected they breath beautifully at 180ft. Got a little syrupy at around 10g/l gas density but that's not typical dive planning and not recommended anyway.
Outperformed my CE stamped modern 'tec' reg when I powered down for a handful of heavy fin kicks test at 215ft and hauled a few hard breaths. Breathed each reg with a minute gap between to calm myself.
All very arbitrary but I am pleased to finally have personally satisfied test data.
Dive safe,
Cameron
Outperformed my CE stamped modern 'tec' reg when I powered down for a handful of heavy fin kicks test at 215ft and hauled a few hard breaths. Breathed each reg with a minute gap between to calm myself.
All very arbitrary but I am pleased to finally have personally satisfied test data.
Dive safe,
Cameron
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