Really, how much creep is a problem.

[herman]

I am not looking for the manf specs but rather an informed discussion form some of the DIY reg techs on the board.
The reason I am asking is I am experimenting with DIY HP seats for several regs, the MK-5 and MK-2 plus the many similar regs that have been sold over the years. I know I can get new SP seats but I have a lot of old regs that parts are just not available for and in some cases I don't even have a clue who made the m so I am working on homebrew HP seats, besides DIY is fun. I chose the MK5 and 2 because I do have new replacement seats for them as control samples and I know I am working on a seat issue instead of a bad piston or HP orifice problem.
SO..... I have had a good bit of success making the seats but slight creep is somewhat of a problem. My results are as follows, the IP will lock up at say 125 almost instantly, creep to maybe 130 over 5 seconds and then very slowly creep to 135 over 24 hrs, it seems to be stable from that point on. Not sure exactly how long it takes to get there but it’s very slow. I personally do not see this as a problem. The 5 psi creep in the few seconds makes setting the cracking pressure on the seconds a little more difficult but otherwise it's not a big deal IMO, the breathing cycle is going to take less time than it takes to settle out anyway and the long term creep is not an issue, the extra 5 psi is not going to have are real effect on reg performance unless you plan to hold your breath for 20+hrs between breaths.
What do the DIYer think, is chasing the extra 5 psi worth the trouble... And in case anyone is wondering, you can make puck type HP seats for darn near any reg for pennies apiece. MK-5, MK-2, Sherwoods, USD Aquarious and a host of others are all easily made. If it has a puck style seat you should be able to make it although the MK-5 and similar types do require a lathe.

 

[LeadTurn_SD]

Hi Herman,

I know you specifically stated you didn't want factory specs, but in this case it might help the discussion.... here is what Zeagle thinks is "ok" for their diaphragm regs:

"The intermediate pressure reading may rise about 3 psi in the first three seconds after lock-up, but after that it should not rise more than another 4 psi (.3 bar) in five minutes."

Your example does not sound significantly different than what Zeagle says is "ok" for their factory-made HP seats....

I'm interested in what others think too....

Best wishes.

 

[Jim Lapenta]

My bad. I was gonna say it depends on who the creep is.

 

[redacted]

As long as you are staying within the IP spec range, I would think you have options. Creep will have some effect on performance but that is going to depend on the 2nd you are using and your tolerance for less than optimum performance. I don't see 5, 10, or maybe even 15 psi of creep as a clear problem as much as a symptom of a possible incipient failure. If this is the way your homemade HP seats perform and the performance is steady, I don't really see any problem.

I am impressed with your craftiness. Let me know when you are ready to try converting a Mk7 to DIN.

We are all going to die.

 

[halocline]

As long as it's not a pony or stage reg that would be used pressurized but not breathed on every few seconds, a little creep shouldn't be a problem. I get really annoyed when any reg I'm working on creeps, but that's just a bit of OCD on my part.

In the case you described, I guess you just assume the IP is more or less 130 and go from there. I doubt you'll have any problem, and if you're talking about a knife edge piston like the MK5, you might find that the creep disappears after a couple of dives, once the piston has had a chance to cut decent groove in the seat. Sometimes my MK10s creep a little after not having been used for several weeks, then after a dive they're fine.

 

[herman]

My bad. I was gonna say it depends on who the creep is.

Hey I resemble that remark.
No problem Jim, I can take a little good natured ribbing and have thick enough skin to ignore the rest. .

 

[herman]

As long as you are staying within the IP spec range, I would think you have options. Creep will have some effect on performance but that is going to depend on the 2nd you are using and your tolerance for less than optimum performance. I don't see 5, 10, or maybe even 15 psi of creep as a clear problem as much as a symptom of a possible incipient failure. If this is the way your homemade HP seats perform and the performance is steady, I don't really see any problem.

I am impressed with your craftiness. Let me know when you are ready to try converting a Mk7 to DIN.

I will put it on the list....do you have a Mk-7 body to spare? I really need to get the idea of making my own first stage out of my head.
I am starting to get a little list of DIY parts projects done :
HP yokes for DAAM/RAM.....done that
DIY balance chamber for SP 109/250s....done that
Custom tools for reg repair...USD HP assembly tool, Voit HP assembly tool, SP bullet, USD & Dacor IP adjustment tool
LP seats for regs....done that
And real close to having working HP seats for most flow by and flow through piston regs

We are all going to die.

At this rate I am leading the pack.

 

[redacted]

I will put it on the list....do you have a Mk-7 body to spare? I really need to get the idea of making my own first stage out of my head.
I am starting to get a little list of DIY parts projects done :
HP yokes for DAAM/RAM.....done that
DIY balance chamber for SP 109/250s....done that
Custom tools for reg repair...USD HP assembly tool, Voit HP assembly tool, SP bullet, USD & Dacor IP adjustment tool
LP seats for regs....done that
And real close to having working HP seats for most flow by and flow through piston regs

We are all going to die.

At this rate I am leading the pack.

Actually, I have both a Mk7 body and a universal din retainer to spare if you would like to take a look at it. It is a Mk7 with the light yoke so is of little use other than parts. One problem is that model does have a third ambient chamber hole that is fairly close to the HP inlet but maybe not too close. If you would like to play with it, send me an address and I'll put one in the mail.

 

[Luis H]

I agree with awap. That kind of creep on itself is not an issue. The only issue is that it may tend to reduce the confidence factor about its long term performance.

That kind of creep is normal in some regulators, but if I see that in a MK-5, I would suspect something is wrong or degrading.


I think you need to make one of this… even better make two… I will buy the second one.

Quick Set - Poppet & Seat Break-In Fixture


You can use one of those to cycle test your seats in order to predict long term performance.


And yes... we are all going to die...

 

[Couv]

Well, I'm going to third, fourth or whatever the number is up to and say that amount and type of creep is acceptable. I am curious to know if you have definitely narrowed down the cause to being your home brewed seats. Have you taken a regulator that has a hp creep and then substituted in a manufactures seat to see if the problem goes and v.v. ? If not, I think Luis is perhaps hinting at what I suspect which would be to make bloody sure you have cycled the reg lots of times. I do not have a fancy machine like the master has posted, but I do have the DIY version. I'll post pictures when I get it back as it is now on loan to a friend. But it is pretty simple. I bought a 175 psi pneumatic relief valve from Granger and put on a couple of adapters so I could screw it into a first stage l/p port. This way I can remove all of the hoses and conserve lots of air when I do the first stage cycling. Air on/air off/pull the ring, pfffft! One cycle. Do that about 30 times and then hook up my IP gauge (also with a very short hose.)

You've gotten much further than me with your DIY hp seat. I bought a rod of Teflon with the same idea in mind; however I was just going to attempt to manufacture the old style puck seats. That's the type my first MK 10 had in it and it lasted for years. That brings to mind my next question. What material are you using for your seats? I went with Teflon because KelF was way too expensive. Finally, I sure would like to know more about your 2nd stage balance chambers.

MK7 with DIN....what a beautiful thought.....I'll sleep well tonight.

c