MK 5 service kit seat not same as mine

The mk5's I have are pretty old.

The service kits have 3 different seats in it (all concave) and none of them look like the one I have (flat).

Do they have multiple mk5 service kits and I was supposed to specify which one?

pactrop:

The mk5's I have are pretty old.

The service kits have 3 different seats in it (all concave) and none of them look like the one I have (flat).

Do they have multiple mk5 service kits and I was supposed to specify which one?

Click to expand...

I am 95% certain that the MK 5 and MK 10 take the same hp seat. That being the case, what you have is a newer type ( I think the current ones are grey) The reson for 3 is so you can easily adjust the ip by changing just the hp seat. Look closely at each one and you will see these markings + - =

Therefore, if you start with the = and need to add ~ 5 psi remove the = and put in a +

couv

Thanks for the info, I was a little worried. even the filter is a different shape. One coned and one a flat disc.

The new and old style HP seats are intercahngable but the filters are not. I believe the concave seats are supposed to reduce the whistling that can occur with the flat seat. The good thing is that you should be able to use at least 2 of the three supplied seats by still using shims for adjustment. I suggest you start with the middle seat and leave the shims that are already there. Then set IP with shim changes if necessary. Then the next time you change the seat, use the taller seat and add a shim or 2; or use the shorter seat and remove a shim or 2 - which ever will work.

I believe the old style flat seats are still available from other mfgrs as are the flat filters. The scubapro flat filter is part # 01-028-101 and hopefully are still available as a seperate order.

I imagine the oceanic flat filters will work; I just bought a MK5 that had what appeared to be a new flat filter that looks a little different (not as good, to be honest) and I assume it's an oceanic or TUSA filter.

Is the original hp o-ring in your MK5 kind of a translucent yellow? What about the one in the kit? Just curious.

The new concave seats are the same for the Mk 5 and Mk10. They allow for a little more range in IP adjustment and in particular allow it to be lowered slightly which is important in some cases as some Mk 5's and Mk 10's with all the shims out still had IP's that were a little too high as the springs apparently stiffen with age - as in 20-30 years worth of age.

The concave design is supposed to improve flow rate as well.

The older HP o-rings were a translucent tan color, while the new ones are made of EPDM and are (I think) black with a red stripe.

TUSA still has the original flat seat design available and Oceanic should still have it for their Mk 5 clone.

THe flat filter is an older design. You have the option to upgrade the yoke retainer that holds the filter - if you can find the part as the Mk 5 is about the only SP reg commonly in use now that does not use the standard universal DIN and yoke retainers. Another option is to just use a flat filter as it is a generic part used on USD and several other makes of regulators. The cone shaped filter has a little more area and goes in a fitting with a larger orifice, so the flow is a little better, especially if it begins to get clogged with salt, rust, aluminum oxide, carbon, etc. but under normal use the difference is not great.

Thanks for all the info.

Mattboy: I will check the o-rings when I tear it apart again.