Scubapro MK15 servicing question

[bada3003]

Thanks for the advice. I didn't know about the 5-year shelf life.

The parts did come in SP packging with the date 03/28/97. As I noted earlier, the packaging was suspect (missing piston o-ring, several used looking components) so unclear how reliable/accurate the date would be. If accurate, some of the o-rings would be at least 16+ years old.

Based on halocline's comments, I've decided to use epdm o-rings that match the specs started by awap's SP o-ring thread. The HP seat and other non-o-ring components, I assume are OK to use. I agree about the high price of some kits I have come across. At least for o-rings, we seem to have an alternative (and maybe improved) option for procuring these critical parts.

I do not have any Mk-15s so I could be off base; if so, I apologize.

1) Every Scubapro factory packaged kit I have ever seen has a date on it. Shouldn't the OP's kit have a date? Looking at the contents of this kit I would estimate this kit dates from the early/mid 90s. The shelf life of urethane o-rings is only 5 years.

2) I was under the impression that the MK-15 used the same seat as the MK-20 and MK-25 (and MK-10+). The MK-25 seat is a darker color, so this is either the wrong seat or an earlier version. I remember an DA Aquamaster post that Scubapro went through numerous different materials trying to perfect the MK-10+/15/20 seat (it was already perfected by the time of the MK-25). Why use an older version seat?

3) My advice (for what its worth) is to be very leery of older kits and kits that have been / could have been opened. I saw a group of older kits that were sold on eBay a while back for what I consider a ridiculous amount of money. I am not sure the bidders understood the shelf life of o-rings.

 

[ams511]

No, the MK15 seat is unique to that model.

Thanks for the information. I will remember that in case I come across any MK-15s.

---------- Post added February 24th, 2014 at 03:06 PM ----------

Thanks for the advice. I didn't know about the 5-year shelf life.

Not all o-ring materials have a 5 year shelf-life, here is a chart for your information.

 

[redacted]

Thanks for the advice. I didn't know about the 5-year shelf life.

The parts did come in SP packging with the date 03/28/97. As I noted earlier, the packaging was suspect (missing piston o-ring, several used looking components) so unclear how reliable/accurate the date would be. If accurate, some of the o-rings would be at least 16+ years old.

Based on halocline's comments, I've decided to use epdm o-rings that match the specs started by awap's SP o-ring thread. The HP seat and other non-o-ring components, I assume are OK to use. I agree about the high price of some kits I have come across. At least for o-rings, we seem to have an alternative (and maybe improved) option for procuring these critical parts.

It may be difficult to find EPDM in duro 90. I use viton for that application. Other than that, my choice between EPDM and Viton is made based on price.

Even the shorter shelf life o-ring materials may last a long time (20 years or more) but you might as well go for newer one if you have the choice. You may still be using them 20 years from now.

 

[halocline]

It may be difficult to find EPDM in duro 90. I use viton for that application.

This is right, I forgot. I think SP uses duro 85 EPDM, which I don't know if I've ever seen. Commonly you can find duro 90 in viton, urethane, and nitrile. Any of those is fine for the piston shaft o-ring.

 

[bada3003]

Thanks for the chart, ams511.

Ordered some o-rings from theoringstore.com earlier today. Couldn't find any "regulator friendly" kit that wouldn't waste half the o-rings, so ordered a bunch of epdm duro 70 o-rings based on SP charts compiled by awap and others. theoringstore makes custom ordering easy.

I did look for epdm duro 90s but as awap and halocline noted they didn't seem easy to procure. Based on the SP o-ring thread discussion, it seemed that using the 70s would work (but not recommended) so opted to go for polyurethane duro 90s available at theoringstore which are a tad firmer than 85 noted in the SP charts. As mentioned in the SP o-ring thread this may not be a bad thing for dynamic o-rings, my main target for fixing the earlier described leaks. The PU o-rings are significantly more expensive though. Didn't check viton and nitrile prices.

This is right, I forgot. I think SP uses duro 85 EPDM, which I don't know if I've ever seen. Commonly you can find duro 90 in viton, urethane, and nitrile. Any of those is fine for the piston shaft o-ring.

 

[ams511]

There is an o-ring exchange thread for swapping and trading O-rings. I know what you are feeling because you can get 100 Buna O-rings cheap from McMaster-Carr or even Amazon but who needs 100 O-rings unless they are for hoses and port plugs or you are in the business. If you are interested in self-service it may be better to sell the MK-15 and invest in a MK-10, MK-5, or even some Oceanic firsts where there are aftermarket seats (and kits) available.

I am not an expert like Halo, Awap, Couv, or Zung, but I would guess that quality o-rings of any material would outlast the seat. I have not seen the EPDM O-rings in duro 85 either. The Viton ones usually come in duro 90 or 75.

 

[bada3003]

I agree with your assessment. The MK15, which I got for next to nothing from ebay (I'm paying more for the kits and o-rings), is my initial "test lab" to hone 1st stage reg servicing skills. Of course, I would like to be able to fix the leak coming from the openings in the ambient chamber, assuming replacing piston and piston stem o-rings does the trick. At first I made a big newbie blunder by thinking that the split backup
ring was the culprit. But when things turn out to be too easy I become skeptical, and, in this instance, for good reason.

My main targets are my MK25 (new) and MK17 (used but serviced recently) which I would like to be able to service competently. Money is one factor, but the other are the stories that regs fail most when they return from the LDS/service techie. My LDS recently went out of business but it wasn't a SP dealer. The owner who is technically oriented and whom I trust can service my Aqua Lung regs, but the SP regs I'd like to do myself.

There is an o-ring exchange thread for swapping and trading O-rings. I know what you are feeling because you can get 100 Buna O-rings cheap from McMaster-Carr or even Amazon but who needs 100 O-rings unless they are for hoses and port plugs or you are in the business. If you are interested in self-service it may be better to sell the MK-15 and invest in a MK-10, MK-5, or even some Oceanic firsts where there are aftermarket seats (and kits) available.

I am not an expert like Halo, Awap, Couv, or Zung, but I would guess that quality o-rings of any material would outlast the seat. I have not seen the EPDM O-rings in duro 85 either. The Viton ones usually come in duro 90 or 75.

 

[herman]

If you can do the SPs there is no reason not to do the AL regs as well. They are easier to do than piston regs IMO...but then again most of my stuff is US Divers/AL.

 

[Peter69_56]

There is an o-ring exchange thread for swapping and trading O-rings. I know what you are feeling because you can get 100 Buna O-rings cheap from McMaster-Carr or even Amazon but who needs 100 O-rings unless they are for hoses and port plugs or you are in the business. If you are interested in self-service it may be better to sell the MK-15 and invest in a MK-10, MK-5, or even some Oceanic firsts where there are aftermarket seats (and kits) available.

I am not an expert like Halo, Awap, Couv, or Zung, but I would guess that quality o-rings of any material would outlast the seat. I have not seen the EPDM O-rings in duro 85 either. The Viton ones usually come in duro 90 or 75.

If you know the material and size, why not just go to an industrial bearing/seal place and buy a dozen or so. That's what I do with most of my O rings unless they are Viton as they are far too expensive from my local bearing place for cylinder neck seals.

Where can you get Oceanic after market seats/kits?

 

[halocline]

The MK15 is an excellent regulator, I wouldn't give up on it. You just need the special snap ring pliers and the kits are not as easy to find as other SP kits. But as an example I found someone with seats that sold me five for $5 each, I figure that should last me a few decades, by which time either me or all the oceans, or both, will be dead anyways. There's a cheery thought!

Once you get done with this reg you should have no problem with the MK25, it's pretty similar. The MK17 is a bit different and there's a tool that's helpful. The AL stuff is quite straightforward, herman makes a handy installation tool, and there's great support in the vintage dive community, assuming your AL stuff is the titan or legend and follows the old 1st stage design leading back to the doublehose regs.