Aqualung SEA Cousteau HP seat

[ganiano]

Hi team,

After 30 great years of use, my Aqualung SEA + Micra has finally given up. The HP seat wore out, and the intermediate pressure started rising above spec.

I decided to do the maintenance myself, following manuals I found online, and great advice from this forum. I disassembled the regulator, cleaned everything with an ultrasonic cleaner, replaced all parts using the 9000-00 Overhaul Parts Kit, and reassembled it. That’s when I ran into a problem.
The new HP seat (part number 1040-20) included in the kit looks quite different from the one I removed. The original seat resembles the 1053 used in the Conshelf 14 — it has a smaller, harder black rubber/plastic insert. The new seat, however, has a much wider and softer blue rubber disc.

When I reassembled everything and pressurized the first stage, the new seat was cut by the crown, and the intermediate pressure began creeping up again.

I have a couple of questions:
a) Do these newer-style seats require a different crown (e.g., one with wider lips)?
b) Should I try sourcing another 1040-20, or would it make more sense to find a different seat entirely (e.g., a 1053 from a Conshelf 14)? I’ve seen warnings that the 1053 may require a different pin length.

Any advice or shared experiences would be greatly appreciated!


I’ve attached a photo showing:

• Left: Original HP seat
• Right: New seat (damaged during install)
• Bottom: The crown

And a photo of the Conshelf parts kit warn (that they include a new HP seat that requires different pin.

 

[rsingler]

The blue seats should work just fine.
The imprint in your picture is MUCH deeper than any I normally see.
That could either be huge pressure from runaway IP, or a defective seat.
In my experience, the new blue seats are more reliable than the old brass ones with a hard black sealing face. When the black ones worked, they worked fine, but were not long lasting compared to the blue ones.

Pin length should only affect the ability to open the valve. In other words, the channel in the blue seat is apparently longer than the Cousteau originally used. If you used a short pin, the valve would not open during breathing. However, on initial pressurization, since the valve is normally open until closed by IP, it might not close until the main spring was so compressed that it finally reached the seat. That degree of compression might yield an IP high enough to destroy the seat. I was unaware of the pin length issue until I saw your photo.
The problem with this reasoning is that with a short pin, there may be no main spring pressure on the seat at all. In that case, the valve would stay closed on initial pressurization, with an IP of zero.

I don't know what could have caused this, but I do feel that the blue seats are better. You can get old seats from Trident, if you want them.
The crown is not the issue; I do know that.

Perhaps others can comment.
@Luis H ?

Note: there are aftermarket blue seats that may not use the same material as the current Aqualung seats, which might also contribute.