Annual servicing - "Check up" vs. parts replacement?

[PrincessOfPower]

Hey, I have a few questions for reg servicers...

I do some servicing for the rental fleet in my dive club, and our policy is to do a full service of any first stage that's come back with the dust cap off. I think that's pretty much the standard common sense thing to do, right? We also always replace the replaceable parts, even if the reg that got flooded was just serviced a month prior, or whatever. It's a solid policy and it lines up with everything I've ever read about reg servicing and heard in training.

So riddle me this - why is it I feel like I have a lot of memories of seeing dustcaps off regs in my earlier days and seeing said regs just left out to dry? Is servicing a flooded reg one of those things that's a good idea, but you can get away with not?

Also, I've noticed some dive shops offer servicing that is more expensive every other year because it involves a parts change. In the cheaper years, the reg is just checked out and cleaned up. I also don't get that, how can a reg be disassembled and then reassembled without changing the seats? If you don't change the seats, how are you going to ensure the grove made by the knife edge lines up correctly?

Anyways, just wondering if anyone had any thoughts on this...

 

[Packhorse]

If you don't change the seats, how are you going to ensure the grove made by the knife edge lines up correctly?

Ever heard of an IP gauge?

If a reg floods in salt water I would open it up clean it out and relube it. A bit of salt water isnt going to hurt the seat or Orings is it?

 

[redacted]

Hey, I have a few questions for reg servicers...

I do some servicing for the rental fleet in my dive club, and our policy is to do a full service of any first stage that's come back with the dust cap off. I think that's pretty much the standard common sense thing to do, right? We also always replace the replaceable parts, even if the reg that got flooded was just serviced a month prior, or whatever. It's a solid policy and it lines up with everything I've ever read about reg servicing and heard in training....

I don't believe it is either standard or sensible. Just what are you reading? How do you figure o-rings and seats are harmed by a flooding?

 

[DA Aquamaster]

I agree with you on the potential problem of having two misalinged seating grooves. When the new groove fully develops you will have two points where they cross that will then potentially leak.

The degree to which this is a problem will vary from model to model and from reg to reg, but why risk it given the low cost of a seat. It's just good practice to always replace the seat if you remove the piston or seat carrier from the reg.

A flow test every other year is one thing, but taking the reg apart inspecting it and putting it back together again with old parts and o-rings just creates the potential to damage the seats and what ever o-rings were removed in the dissasembly process. So either flow test it and be satisfied or rebuild it, but don't screw around with anything in between.

Rebuilding a first stage just becasue the dust cap is off seems like overkill. Removing the filter and inspecting it for signs of water or salt and similarly removing an LP hose to inspect the interior for water makes some sense, but a full rebuild is a lot for a dust cap that was left off absent any further indications of flooding. But hey, if the shop pays the same for the rebuild, its their money and their business.

 

[jsf35]

I agree with DA Aquamaster. If the reg was submerged with the dust cap off, then inspect the inlet filter area. Flat sintered filters do an OK job of keeping water out. Cone style filters may trap some though. You can also remove the HP hose and pressurize the reg slowly and check for moisture blowing out. (Don't forget ear protection when doing this).
As for rebuilds, any time a reg is disassembled, any parts that normally get replaced during an annual servicing should be changed. Unless the regs are Apeks, service kit costs aren't too outrageous. Some manufacturers have gone to a 2 year servicing cycle with a bench test performed during the odd years. This involves checking the IP over a range of supply pressures, checking the second stage cracking pressures and a leak test.
I service regs for commercial and fish farm divers as well. Some of these never see a fresh water rinse and quite a few don't even have dust caps, and I haven't seen one yet that failed due to salt water ingress.

Cheers,
Scott

 

[redacted]

I agree with you on the potential problem of having two misalinged seating grooves. When the new groove fully develops you will have two points where they cross that will then potentially leak.

The degree to which this is a problem will vary from model to model and from reg to reg, but why risk it given the low cost of a seat. It's just good practice to always replace the seat if you remove the piston or seat carrier from the reg.

.

I'm sure it is very different doing this work for a paying customer vs. DIY and that is probably why I am reluctant to replace a perfectly usable part such as a seat or even an o-ring. Heck, I've still got red, blue, and purple o-rings in some of my Scubapro regs.

I have not had much trouble opening up my Mk 20/10/7/5 without having to replace the seat. Mk20/25 is fairly easy as the piston does not seem to cut the seat. But I have seem multiple rings in older style seats and the associated IP creep problem. When I have to open up my older BP regs, like to relube the HP piston o-ring, I always check the IP first. If it is good, I remove the seat retainer but don't disturb the seat within. I also note the position of the piston in the body. That way I can reassemble with everything in about the same position. A recheck of IP will tell you whether you hit the old groove or have a problem. It is easy enough then to go back and replace the seat if necessary.

I guess as long as someone else is paying for it, it may make sense to be safe rather than sorry.

 

[PrincessOfPower]

Thanks all! Good to get some corroboration to my thinking process.

Yeah we don't needlessly service *just* because a dust cap is off - when there's a good chance water is in the first stage (in a drippy salty bucket of gear, for example) then we do. And we also charge a servicing fee that covers those costs.

Cheers,

 

[Luis H]

I'm sure it is very different doing this work for a paying customer vs. DIY and that is probably why I am reluctant to replace a perfectly usable part such as a seat or even an o-ring. Heck, I've still got red, blue, and purple o-rings in some of my Scubapro regs.

I have not had much trouble opening up my Mk 20/10/7/5 without having to replace the seat. Mk20/25 is fairly easy as the piston does not seem to cut the seat. But I have seem multiple rings in older style seats and the associated IP creep problem. When I have to open up my older BP regs, like to relube the HP piston o-ring, I always check the IP first. If it is good, I remove the seat retainer but don't disturb the seat within. I also note the position of the piston in the body. That way I can reassemble with everything in about the same position. A recheck of IP will tell you whether you hit the old groove or have a problem. It is easy enough then to go back and replace the seat if necessary.

I guess as long as someone else is paying for it, it may make sense to be safe rather than sorry.

I tend to agree with you for personal gear. I have on occasion seen double grooved Mk-5 hp seats. But for the most part I have been able to clean and reuse the seat with no IP drift and when I finally replace it, the ring is a single sharp groove. The concentricity tolerance on all my MK-5 seem to be tight enough that it has never been a problem.

In the old days I used to flip the white flat seat on my own regulators. I do like the new concave seats.

I also don't tend to replace O-rings if they look in good condition, show no signs of set, they are perfectly round with no flat spots, no nicks, etc. I can also normally tell by the amount an O-ring is still having to compress during assembly, if it going to work well or not.

Parts are cheap, but I have too many to be wasteful. Then again I only use my Mk-5 for local diving while working in the lake.

It is just a personal choice, I am not recommending it to anyone else.
I do tend to subscribe to "if it ain't broke don't fix it" idea.

 

[cyoung]

By no means do I consider myself an authority on the subject.
Our dive shop is a small mom/pop shop, I am a part timer about
1 or 2 regs a week, depending on the influx, sometimes nada for a spell.

I have to agree with DA on the seat getting a double groove. That's a case for a possible leak and overpressureing the 2nd.

I'm a machinist by trade, and we build rotary air joints (single, double, and triple passes), as well as other items. These rotary joints are low pressure (150 psi or less). I've seen O Rings fail to seat, because of a missed tolerance of only a few thousands.

Now consider 3000 psi, a used O Ring, it may look and feel good. But who's at the end of the 2d stage.

If its yours, and your doing the work, so be it.

But I always replace O Rings.

O Rings: generally speaking O Rings rely on only .004 to .007 crush for sealing.
For the cost of an O Ring, why risk the failure of a used one.

Service intervals: Some mfg may recommend annually or longer. They built 'em, hopefully they know. But it stands to good reasoning, that if you dive a 100 or so dives a year in SW you might want to consider an annual program. Now, someone that makes a vacation dive every few years, that one needs to be checked before getting in the water. A lack of use can cause parts to mmm, be sluggish, if that makes sense.

Enough, just two cents worth.

Carl

 

[superstar]

In the Scubapro manuals I find no information on tolerances for the piston, the body, or the cap. How do you tell if these items are in tolerance and the o-rings will seal?