Scubapro Mk-5 and 109 service kits.

[Zung]

Urethane is good because it's white and therefore easy to identify.
SP has to paint a red stripe on all their 2-010 EDPM 90's to tell them apart from the 70's that are also packaged in the original SP kits.

 

[Greg Barlow]

I think it is a great idea. Bryan at VDH does an outstanding job of providing high quality parts for various DH regs, and I am certain that these will be the same.

Greg

 

[parzdiver]

This is a great idea.

 

[DA Aquamaster]

DA - why the concern with viton? Is it just in that application or do you have a problem with viton in general. I usually favor EPDM, but viton seemed to have better availability, particularly in duro 90.

The Mk 10 can be hard on the piston stem o-ring. The reg was designed in an era where 2250 psi was common and 3000 psi was considered to be on the high side, so the reg was designed accordingly. As pressures get over 3000 psi, the piston stem o-ring begins to have greater issues with extruding into the clearance between the piston stem and the reg body, then when the piston moves, it can pinch the o-ring and slice off little cresent shaped pieces.

SP moved to a 90 duro o-ring to reduce this problem but it can still occur in regs where the tolerances for the piston and reg body get stacked in the wrong directions creating a larger than average gap.

I noted that viton o-rings, even 90 duro viton o-rings tended to get beat up worse than nitrile or EPDM o-rings. I noted that many of them would end up with feathers where the extrusion was occurring.

I have not had the same number of issues with the Mk 5, and that suggests that perhaps the tolerances were generally tighter.

Urethane is good because it's white and therefore easy to identify.
SP has to paint a red stripe on all their 2-010 EDPM 90's to tell them apart from the 70's that are also packaged in the original SP kits.

I am not a fan of urethane. They tend to get dry and crispy and scubapro discontinued them for a couple good reasons, another one of them being the o-ring pinch issue at higher pressures and 3442 psi is a lot more common now than it was then. If you want some, I think I have a lot of them somewhere.

Identifying the 90 versus 70 duro o-rings in the kit is not hard even with no paint as the 90 duro o-rings are noticeably stiffer when you squeeze them.

 

[halocline]

I had a batch of dried urethane o-rings, but the good ones were fine, so I attributed it to just an old-stock batch or something like that. I really did notice a difference in IP rise at higher tank pressures between the urethane and the nitrile. I had assumed that SP discontinued using urethane for cost and simplicity reasons, not performance issues. You learn something new everyday!

 

[Luis H]

Thanks for the comments. I will send a link to both of these threads to Bryan to read.

Thanks for all the information DA Aquamaster. I am glad to see that our observations are similar.


The combined MK-5 and Mk-10 kit sounds like a good idea. I will pass that along.


I like the individual parts idea also, but he may need to introduce the kits first. IMHO, he is investing some money up front and need to recover enough to keep the business worth while.

He used to only offer service kits for double hose and now you can buy any individual part. I think a lot is going to depend on how much demand he gets.


I believe that Bryan is planning of using (or at least starting of with) the HP seat from Trident PN A242. Does anyone have any experience with it? I should be getting some soon to test out, but have not seen one yet.

A flat seat is always a possibility. Again it is all one step at a time.

 

[halocline]

If somebody buys awap a plunge router, he'll make concave Mk5 seats

 

[Luis H]

If somebody buys awap a plunge router, he'll make concave Mk5 seats

I just had a chance to check with awap and he is using at least one Trident seat.

The issue you mentioned to me had to do with the dive shop not the part. He said the seat is working fine.

Hopefully he will stop by and comment on the parts.

 

[Eric Sedletzky]

I know this stuff is being developed with MK 5's and 10's in mind, but would the same kits work in say a MK20/G200 or a MK2/R190 ?
Just asking.


And what about MK3's. I need a 90 duro 019 O-ring for the piston.
I used a standard 019 I found at a hardware store and it seems to be working for now on 2250 psi, but it's probably 60-70 duro and pretty soft. I looked throught my MSC catalog and they list all the O-rings you guys mention but most are in the 70 range with a few at 80, nothing in the 90 range.

Am I understanding the term "Duro" correctly meaning the hardness of the material?

Can I get away with a slightly softer O ring in my MK3 if I stick with 2250?
What happens if a piston O-ring blows out in the 1st stage, do bubbles come out of the ambient pressure holes like crazy?

 

[Fishpie]

How about a kit to convert a 109 to a BA.