Conshelf first stage seat failure.

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

scrane

Contributor
Messages
2,121
Reaction score
1,965
Location
Boise, ID.
# of dives
500 - 999
I just hooked up the Conshelf SEA first stage I rebuilt agout 6 months ago. Today, much to my amazement, the second stage I attached started free flowing like crazy (thank goodness). I had checked out the first stage right after I rebuilt it and it was fine. I dismantled the reg from the diaphragm side and noticed the pin was not centered in the pin support bore. UhOh. I flipped the reg over and dismantled the HP side and found this:

seat.jpg


It looks like the seat from the rebuild kit was defective under load, but I just wanted to check if I might have done something wrong on assembly. Has anyone seen anything like this before?
Anyways, back together under pressure to check for creep/ possible crown damage.
 
Holy crap. Where did you source that seat?
 
Wow.
Luckily it happened on land(home/workshop).
 
I dismantled the reg from the diaphragm side and noticed the pin was not centered in the pin support bore.
What do you mean by the 'pin support bore'? Do you mean the hole in the seat that the pin goes into? Or the pin support on the diaphragm end? Maybe this is obvious, but it looks like the pin caused that damage, like it came out of that hole and destroyed the seat. I have no idea how that could have happened other than in assembly, and then you would have discovered it when you first pressurized. I haven't worked on a diaphragm reg in quite a while so I'm not exactly clear on whether or not this is even a possibility, like would you even be able to assemble it without that pin correctly installed in both the seat and the pin support on the diaphragm end. Maybe if the pin came out of the support it could stay in the hole in the seat for a couple of pressurizations but then slip out. That's just a guess.
 
Thanks for your comments.
When I dismantled the diaphragm the pin was properly engaged with the seat assembly and the pin support. Then when the pin support was pulled the pin fell to an off center position in the main body bore that encloses the pin support. The pin support and seat assembly (except where the seal was blown out) were undamaged. The pin was straight. I think the seal blew out spontaneously and the pin and seat went cockeyed when there was no longer a flat sealing surface to support the seat when the pin support was removed.
The seat, pin, and pin support are held tightly together by opposing spring forces from the main spring and the two springs on the HP side. I don't see how they could decouple or be assembled improperly.

img
 

Back
Top Bottom