APEKS diaphgragm first stage: How much IP creep is ok?

[Markos Valsamis]

I have now serviced around 30-40 first stage regulators from Apeks (DS4, DST etc). The below relates to the regulator straight after I have serviced it (official parts, ultrasonic cleaner, etc).

Some first stages seem to have a very clean lock-up at a particular IP, others will immediately go to say 9.3bar and within an hour creep to 9.8bar and lock there indefinitely, and another cohort will continue creeping steadily.

My question is about the middle cohort- the apeks manual says anything more than 0.25 constitutes a creep but in my experience a great number of regulators will creep around 0.5 from the very initial IP lock-up, and often this occurs mainly in the first minute or so.
*in order to ensure that further IP creep is not prevented by a leaking second stage, I have always also tested this cohort by having ONLY a inflator hose coming out of it (and monitoring it closely so as to not hear an explosion in the middle of the night)- the same behaviour ensues.

What are your experiences? Is this something to be concerned about? Is there a recognised cause for this? I have tried various things including re-servicing those regulators, but often I cannot change this weird behaviour.

 

[tbone1004]

how much creep is ok? none

What you are describing is IP drift and going from 9.3 to 9.8bar is not something to worry about.
It may or may not settle down after a few hundred cycles, but if it locks up then I wouldn't worry about it.

 

[Markos Valsamis]

how much creep is ok? none

What you are describing is IP drift and going from 9.3 to 9.8bar is not something to worry about.
It may or may not settle down after a few hundred cycles, but if it locks up then I wouldn't worry about it.

Ah, thanks I didn't realise this is different. Is it known why this occurs? I would have thought if there is any change in IP at any point, it means there is a leak, and to be honest I have been surprised it doesn't just continue increasing (which would make sense if there was a leak)?

 

[tbone1004]

Ah, thanks I didn't realise this is different. Is it known why this occurs? I would have thought if there is any change in IP at any point, it means there is a leak, and to be honest I have been surprised it doesn't just continue increasing (which would make sense if there was a leak)?

Just a delay for the HP seat to seal completely. Happens sometimes when there is a very minor defect on the hard seat in the body and it takes a second for the seat to cover it or conversely a minor defect in the hard seat. Once there is a deeper "set" from the crown into the HP seat it usually locks up faster.
With Poseidon first stages it means it is time to polish the bullet, but not much you can do on Apeks first stages

 

[runsongas]

for those that have a mushy lockup, look up @rsingler thread about polishing the orifice with magic mesh

 

[Centrals]

Do not forget to clean and check the orifice. Easy for the FSR but not the others.

There is a Apeks tool to polish the orifice but I use clean pencil top eraser! It works.

 

[GF99/99]

I own around 15 various (DST, DS4, UST, US4, etc) Apeks first stages and over the years a couple of them were doing as you described. I used the Apeks polishing tool on the orifice and this helped but they still have a little bit of "drift" but nothing I'm concerned about. They drift up about .3-.6 bar after sitting for about 30 min to an hour but lock up there.

If you message @buddhasummer you can order one. Or as mentioned above you can try the pencil eraser trick, I have heard from other as well that this works too.

 

[admikar]

One thing that was told at my service course is to not worry too much about drift immediatelly after servicing the reg. It can take over 100 cycles for everything to set properly. Creep is unacceptable.