MK 10 HP seat

[Couv]

In some of the archived post, some of the SP gurus indicated that some of the concave seats available for the MK10 were made of inferior material. I have the old style knife edged piston M10; however, the kits I bought off ebay are the concave style. How can one tell if the material the HP seats are made from is the newer/superior type or the type I would rather dispose of than install?

I am assuming that I can use the concave HP seats in place of the hockey puck style or is there more to it.

Thank you,

couv

 

[DA Aquamaster]

The new seats are a solid light gray in color.

The older seats that could be problematic were made of colored material that was much more translucent. The color varied a bit as they changed materials. - I remember red seats and a browish orange colored seat. The seat material in the concave seats seemed to be more of a problem in the Mk 15 and Mk 10 Plus as both of those first stages used a rounded seating edge that was more prone to IP creep to begin with. The rounded seating surface on the piston improved the flow rate slightly, but due to reliability issues, SP kept the concave seat design, but dumped the rounded seating edge during MK 20 production and went back to a more conventional knife edge design.

The new Mk 10 and Mk 10 Plus seats also come in three different heights to allow the Intermediate Pressure to be changed without having to remove the piston to add or delete shims. Plus some older Mk 10's seemed to have problems with excessive IP as the springs got a bit stiffer with age. Removing all the shims was often not enough to get the IP under 140 psi. The tallest of the new seats allows you to keep the IP within limits on these regs without having to replace the spring. All three seats come in the Mk 10 and Mk 10 Plus annual service kits.

The new concave seats are a direct replacement for the older white (yellow after they were used a while) hockey puck seats. But since they come in three heights, it is best to check the IP to detemermine which one you want to use.

You can make an inexensive IP gauge with a 1/4" NPT to QD inflator fitting from your local dive shop (who can order it from Trident if they don't stock them) screwed into a 1/4" to 1/4" nipple which is in turn screwed into a fairly inexpensive wal-mart or hardware store variety air tool pressure gauge with a 0 to 200 psi range. Be sure to use teflon tape as you don't want the fittings to leak. You can also buy a gauge from peterbuilt for $21.00 (79-201-000) They cost a little more, but are calibrated to be accurate in the critical range.

http://www.scubatools.com/Gauge.html

The 1/4 to QD fitting is probably $5.00 and the nipple should be under a buck at the local hardare store.

 

[Couv]

Boy that was quick! Ask a question, go eat supper, come back and there is an answer there waiting.....took my breath away!

Thanks DA...gray is what I have.