IP Creep Testing

Just got back my regulator that was repaired due to a bad HP seat.

Unfortunatley I am headed out for a dive trip next week and do to weather, will not be able to test them in the quarry or a pool before leaving.

I was hoping one of the Technicians here could advise me on the best way to be sure there is no IP Creep, prior to my leaving. Don't want a freeflow during my trip and then have to rent equipment.

I have an IP Gauge - but not sure if just leaving it on for an hour or two on a full tank is sufficient testing or if I should breath off the reg several times during the time it is under pressure?

Thanks in advance for your input

Put the IP gauge to it. An IP creep problem will show up in seconds or minutes, not hours. It should either lock up (almost immediately with a new seat) or it will continue to slowly rise. If it does slowly rise, it will either shortly lock up in spec or eventually find a way to vent - probably thru a well tuned primary 2nd. If it does not lock up immediately, cycle the 2nd a couple dozen time just in case the tech did not break in the new seats and try again. Do this in the bathtub and you will be able to see any leaks. You may not want to log it, but if the tub is big enough, you can get a better than nothing performance check before your trip.

Enjoy.

BTW, I am not a tech - just as DIYer.

Don't let him fool you, tech or not, AWAP knows more about regs than most techs.

Appreciate the information

I am a DIYer myself, just have not yet assembled the tools for a first stage rebuild - so I had to have this one done by the shop. I do my own second stages, since I will tune them alot tighter than the shop will.

I've checked it out - cycling the second stage several times and everything looks good.

Can't wait to get them wet.

Thanks again

If you are using pneumatically balanced second stages, then IP creep is even more critical. IP creep on such a reg typically does not cause the excess gas pressure to vent until it reaches a troubling level. If you are using a non-balanced second stage on the first stage it will begin to leak when the pressure reaches a level where it forces open the downstream valve by overcoming the valve spring tension. The IP will then drop to the threshold level and begin to climb again.

As the IP creeps upward, it will often reach a point where the pressure forces the seat against its sealing surface. This will generally get worse with repeated cycles.

Manufacturers set limits on how long it takes for a first stage IP to lock-up. Generally speaking, the pressure should stabilize within 10-15 seconds or so. It is not real uncommon for the pressure to rebound quickly, and then slowly creep upward 3-7 psi or so. Of course, this is only a generalization and each reg has its acceptable limits.

BTW, I check my reg's IP around every dozen dives or so. It, along with a field check of cracking effort, gives me a good general field view of a reg's health.

Greg Barlow

Greg

What you described is exactly what I was seeing - pressure would rebound quickly to about 139 psi and then creep to 143 psi over about 5-10 seconds.

All my other regs just instantly return to the set pressure and stay there - therefore my concern.

After cycling the reg several dozen times by purging or breathing through the 2nd stage - it now rebounds to about 142 psi and maybe goes up a pound after that.

By the way - all my regs are Mares - either MR-22s or 32s - with either Abyss or Proton 2nds.

TN Traveler:

I do my own second stages, since I will tune them alot tighter than the shop will.

Click to expand...

Tighter as in precise? or as in reluctant to (unnecessarily) freeflow?

There was an incident of a Tech diver experiencing a run away inflator because his `1rst stage was creeping and he kept tuning his 2nd to prevent a freeflow.... the second will function as your OPV in case of a 1rst failure... so careful you do not over "tune" because the pressure has to go somewhere

By tighter i mean that the LDS tend to set the cracking pressure at 1.4 - 1.6 inches - I set mine to 1.1 to 1.2 inches - takes more effort and time to do this - but I really like the easier breathing.

I know, I could just buy regs with an adjustable second stage - and it would be easier. But I also like the all metal second stages - lots less dry mouth.

It's normal to see the initial swing and then a 3 to 5 psi creep over a few seconds until it locks up, especially on a new seat. Any creep longer than about 5 seconds is something I'd worry about and fix before I send it home with the owner.

Once a seating groove is established in the HP seat, it's common to see it lock up immediately at the top of the swing. Usually, leaving the reg pressurized over night and/or cycling it multiple times will speed the break in process. If you want to spend big bucks you can get a machine that will cycle the reg very rapidly and with very little airflow and adibatic cooling. But unless you service a lot of regs, it's not worth it - and it's not really needed in 99% of the time.

No need for the "big bucks" solution.

I left it on the tank all day today and whenever I went into the garage, I cycled it a couple of times - it now goes right to 143# and stays.

Thanks to all for the helpfull information. I now feel fine about taking it on my trip next weekend.

Dive Safely