Diaphragm first stages often have lower flow capability than a piston and are less responsive (small orifice), for example, the advertised flow rate for the AL first stages is 1500 lpm vs 6000 lpm for a Mark 25 type and 3000 (-) lpm for the little unbalanced piston Mark 2 Evo. Most, if not all, diaphragm first stages use a wire push pin to off set the HP seat upstream from the volcano orifice and that wire pin must go through the orifice therefore partially occluding it. Then there is the ambient diaphragm, which can leak, tear or burst or slip out if not installed properly and even then over time the material can compress and leakage/slippage becomes possible. And, while we are discussing balanced diaphragm first stages, true, the balancing reduces the force needed to open the seat, the HP seat is still being pushed open upstream by a wire pin connecting the HP seat to the ambient diaphragm. Diaphragm first stages also tend to have a lot of (moving) parts or springs and the perishable ambient diaphragm.
My latest infatuation is with the cute little AL Core Supreme/Helix Pro diaphragm first stage, tiny, well balanced, fully sealed and with some good improvements and some simplification vs it's evolutionary predecessor, the Conshelf. The Conshelf, egads, uses a circlip to retain the guts, geeez!!!!! If the circlip groove is damaged, the clip looses it's compression or is installed upside down or one of the springs internally below or above the crown block balance chamber becomes coil bound (overly long wire pin) the innards can eject themselves. And there have been at least a few cases of buckled or bent wire push pins.
These are incorrect statements (I am referring too all the bolden statements). Not only they are incorrect, they have no basis in reality and no substance to back it up. I am sorry my friend, but you should be embarrassed of repeating such nonsense which I can prove as totally incorrect.
Yes, I have data and plenty of analysis and substantial facts to back my statements. Please notice that when I am sharing an opinion, I always mention something like “IMHO”, but in this case I have plenty of data to show that the stamens above have no basis in reality.
In a balanced diaphragm regulator like the Conshelf, the Titan, the Royal Aqua Master, and many others,
the only thing that keeps the first stage valve closed is the spring. The force provided to keep is closed is about 8 pounds (I have measure it many times) and it is not affected by tank pressure. I have measured this many times as a function of changing tank pressure.
If the spring is not strong enough to create a good seal, it is not uncommon for a Conshelf to operate and seal perfectly well with tank pressure of 2000 psi or lower. But
if the closing spring is weak, it will free flow with higher tank pressure. The tank pressure does not have any tendency of closing the valve. I have tested and proven that many times.
The higher tank pressure actually tends to open the first stage valve seat not close it. That is a fact that I can show you on any Conshelf. That is not the same as in a non-balanced Aqua Master.
BTW, I have also done plenty of buckling calculations on the pin and the statement that
a pin can buckle under the required opening force is total and complete BS.
I do have pictures of one buckled pin that was way over a 1/4 inch too long and the guy installing it, used the threads on a Phoenix during installation to apply the king of compression force required to buckle the pin. It really requires that type of stupidity to buckle the 0.06” diameter stainless steel pin. This is not a wire and trying to call it a wire is complete BS.
Yes, I have done plenty of elastic instability analysis to determine the maximum length the pin can tolerate. We are not even close to a buckling failure. I will be glad to show you actual facts and data, so that you stop talking BS… The aspect ratio of length to diameter describes it a slender column, but by definition, it is a structural column. Yes, it is a very small column, but the aspect ratio is not much different to other columns that you would never question.
If you have some actual pictures of the bent pins I will be glad to do a failure analysis. Yes, I know of the
one BS article that has no actual substance of facts to back it up (that you like to quote). That one article has received a lot of mileage and it really only shows one persons opinion of how one regulator failed, but it has no pictures or actual data to back any substantiated failure analysis. That article is total nonsense and (INHO) technically embarrassing.
I will leave all the other nonsense alone for now.
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I love you Luis but the Conshelf type first stage is just an old flame that I am moving on from.
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