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.

 

[herman]

There was a version of these seats that had a shallower pin hole but were not used long. To my knowledge, the older seats with the shallower pin depth were only used in early Voit regs, never seen it in a USD but knowing USD , they may have used it in a pinch. Voit had a replacement kit that was used at service to upgrade the reg to the newer seat, just a new seat and pin. I haven't seen one in a USD reg and even if they were used, it was very early. This reg was made way after the seat change. Looking at a 2000 service manual for the SEA and parts manuals from 2000 to 2014, the HP seat number is the same for it as well as every other AL reg-SEA, Conshelf, Titan and Legend.
If by some really odd change you do have one of the older style seats, someone in the past installed it...no telling why.

 

[herman]

By the way, creeping HP on USD/AL regs is often caused by defective balance chamber or it's orings. You may well be chasing that instead of a bad seat.

 

[ganiano]

Thanks so much for the valuable information!
I just ordered a new HP seat (the newer blue version).

I replaced the LP chamber membrane along with the other parts (O-rings) from the service kit, but I might not have set the LP spring adjustment correctly before assembling the HP chamber. That could have caused the HP springs to press too hard against the seat.

I’ll reassemble the regulator carefully when the new HP seat arrives in a few days and will follow up afterward.

Really appreciate all the help—thanks again!

 

[bradlw]

I have the same US Divers SEA + Micra regulator! Where did you source the kits from?

I was under the impression that since these regs are long since been discontinued that OEM kits are unavailable. I understand that "similar" HP seats can be had from Trident, but the other parts such as the 2nd stage seats and diaphragms, would be "punch your own" from a rubber sheet.

I did contact Airtech fairly recently, and they replied that service kits are still available..but their lead time takes it out way past my summer vacation trip that we're planning to do a dive

since these old regs are orphaned by at least a few parent company shifts,
and since a non DIY service would be at least $85- $140 (IF they can even get the parts)
and considering I probably ought to get new hoses (they were well used when they were put into storage around 20-years ago)..so add on another $130 or so.....
That puts me halfway towards a decent new regulator set!
I've been on the fence about just buying a new set

I was never factory 'certified' but I was taught how to service them from my trimix tech instructor many years ago and I have the tools needed. It's been so long, my memory about it isn't fresh, and I'm only mildly interested in getting that deep into it at the moment... BUT I could and might if I could easily source some complete kits

 

[GJC]

I have the same US Divers SEA + Micra regulator! Where did you source the kits from?

I was under the impression that since these regs are long since been discontinued that OEM kits are unavailable. I understand that "similar" HP seats can be had from Trident, but the other parts such as the 2nd stage seats and diaphragms, would be "punch your own" from a rubber sheet.

I did contact Airtech fairly recently, and they replied that service kits are still available..but their lead time takes it out way past my summer vacation trip that we're planning to do a dive

since these old regs are orphaned by at least a few parent company shifts,
and since a non DIY service would be at least $85- $140 (IF they can even get the parts)
and considering I probably ought to get new hoses (they were well used when they were put into storage around 20-years ago)..so add on another $130 or so.....
That puts me halfway towards a decent new regulator set!
I've been on the fence about just buying a new set

I was never factory 'certified' but I was taught how to service them from my trimix tech instructor many years ago and I have the tools needed. It's been so long, my memory about it isn't fresh, and I'm only mildly interested in getting that deep into it at the moment... BUT I could and might if I could easily source some complete kits

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Silent Explorers, Brooklyn Park, Minnesota, United States, online sales vintage Aqua Lung Double Hose Regualtor parts, Poseidon Rebreathers Regulators, Professional CCR Regulator Service, Shearwater Dive Computers

www.silentexplorers.com

 

[ganiano]

I found the repair kits on eBay from someone who said they were a retired technician clearing out old stock. Maybe the HP seat I received was old or dried out—that could be why it broke during assembly. While I agree that fully rebuilding both stages might not make the most economic sense, this regulator has served me well over the years, and I’d really hate to let it go. I wasn’t able to find the demand membrane for the second stage (a non-adjustable Micra), so I’ll have to stick with the old one for now—though I might be able to find a compatible part from a different model.