A bump up

[captain]

I posted this back in 2010 and since we have gained members some might find this useful.

When rebuilding diaphragm 1st stage regulators I always take several days to finalize the IP setting, here is why.
Ever look closely at a used HP diaphragm, you see the impression made by the spring pad on one side and the pin support pad on the other. Over time the diaphragm becomes compressed and molded by the spring pressure. I have measured the compressed and
un-compressed areas of the diaphragm and find a .015" to .020" difference in thickness.
If you set the IP and forget it the diaphragm will slowly compress over a period of days. This will caused the spring to be sightly unloaded and result in the IP decreasing over time.
The IP adjuster screw moves .010" in or out with each flat or 1/6th of a turn and after several days it may require turning the adjuster nut one to two flats in to regain the wanted IP.
Set the IP and walk away from it for 3 or 4 days then come back and check it and reset if necessary.

[Bryan]

Thanks for sharing Tom. Word to the wise.

[Bronze06]

Great post and very true. This can apply to ALL regulators. Many of us forget about the regs we rebuild and set to a given IP, then wonder why performance isn't what it was after a month or too. I am pretty nit-picky when it come to compression differentiation over time so I always go back into the reg and re-check IP after about a month or two.
Funny that this topic has been brought back into the lime light in that I did the very same thing with my Kraken diving with it A LOT for about 9 months without adjustment straight from the "factory". I noticed that after time I wasn't getting the performance I had initially and FINALLY went into the reg and checked IP. IP was at 118! The reg still breathed well even at this IP, but not like it did when I first received it. I re-set IP to 135 and it of course breathed better than ever. What makes this interesting is that I always re-check IP on all my rebuilds, but with my Kraken I got a "Brain Fart" and assumed that everything is peachy, just like some shave-tail newbie diver. Bottom line is that component and diaphragm compression over time is one of the reasons the dive industry rightfully uses to justify annual reg checks and services. Thanks for reminding us guys.