Help to identify and advise on an older Poseidon regulator

[Fitzgig]

I have scanned the board but have not found the definitive answer. I am a noob- so it could be inexperience. Apologies in advance.

My sister gifted me her old Poseidon regulator and the only thing I know is that they are nearly impossible to get serviced in the US - but that they are well manufactured. Can someone help me identify and advise me on whether it is worth the difficulty /expense to have it repaired? @rsingler seems to be THE guy to ask, but any advice is valued. Sounds stupid, but I would like to use them in the future in my sister’s memory. I think the manufacture date is 1996, back when she was a healthy vibrant dive master……

 

[Fitzgig]

So water under pressure would not penetrate the diaphragm seal but vodka or glycerin would? Was there a bulletin from Poseidon about this?

This is an interesting observation. I wonder what the answer is…….

 

[Bigbella]

So water under pressure would not penetrate the diaphragm seal but vodka or glycerin would? Was there a bulletin from Poseidon about this?

Aside from that illustrative photo above, from an old German manual, with that obnoxious "X" through the 3950/60s, there was little else mentioned by Poseidon.

It may just have to do with the nature of the newer, translucent diaphragm material, which was definitely not as tough as the older version, which I continuously flipped and flopped with every rebuild, for a few years, especially when out of country; a starving student, and light on cash.

Typically, we winterized the regulators in -- go figure -- the winter and whatever crap we were using, whether vodka or alcohol / glycerine concoctions, would sit on those diaphragms, for half of a year, at least.

I do once recall servicing some 3950s which had been flooded with an amber, syrup-like goop for some odd reason, and which had been a colossal pain in the arse to remove.

Perhaps, that newer version was just more sensitive to some polar solvents like isopropanol, which had routinely been used as an antifreeze?

 

[rsingler]

Without knowing, I took that red X to mean only that the new cap (the Frostschutzkappe Metall) would not fit on the 3960, and not that the vodka cap was verboten. After all, there is still the ridge on the 3960 body to accept the rubber cap.
Now I need to go check my manuals...

 

[rsingler]

Well, I don't see the cap in the schematics like I do in the 2960...

More research underway...

 

[Bigbella]

Without knowing, I took that red X to mean only that the new cap (the Frostschutzkappe Metall) would not fit on the 3960, and not that the vodka cap was verboten. After all, there is still the ridge on the 3960 body to accept the rubber cap.
Now I need to go check my manuals...

I am quite sure that the metal cap threads were attachable, at least, to all first stages, from the 300s, on, through the 3950 / 60s. It's honestly been a while, but I had thought that I had attempted that some years back . . .

 

[p_kos]

Well, I don't see the cap in the schematics like I do in the 2960...
View attachment 818307
View attachment 818309
More research underway...

I do.

 

[rsingler]

Mystery solved!
I wish I liked the new 3960 diaphragm as much as the old 2960 one.
Here's that reg that leaked after reassembly until I replaced the valve center, lower (3722).

It got put away with a milliliter of water in the spring chamber. That brown stuff was only on one side. The corrosion goes all the way down to the oring land, and could not be scraped/ polished out. Notice that everything is pristine on the inside of that land.

 

[p_kos]

Mystery solved!
I wish I liked the new 3960 diaphragm as much as the old 2960 one.
Here's that reg that leaked after reassembly until I replaced the valve center, lower (3722).
View attachment 818314
View attachment 818313View attachment 818312
It got put away with a milliliter of water in the spring chamber. That brown stuff was only on one side. The corrosion goes all the way down to the oring land, and could not be scraped/ polished out. Notice that everything is pristine on the inside of that

That’s ugly.

 

[Bigbella]

It turns out that all of those verboten antifreeze caps -- metal and otherwise, fit perfectly on the 3950 / 60s -- I hadn't lost my mind . . .

 

[rsingler]

Well, I do my triennial Poseidon recert next month. I'll ask the guru what the story is on the Frostschutzkappe Metall and the 3960. That would make me like this reg a whole lot more.