Help on using IP Gauge to test reg

[mi000ke]

I’ve done a lot of searching here and on the web to try to understand how to use an IP gauge to test my regulator. I have a general idea of what to do, but am looking for a bit more specific information. Please see if I have this right and correct me where I am off, Thanks!

As I understand it, there are three things I am looking to test:

1. Actual intermediate pressure: assuming no creep, does the IP fall within the manufacturer-specified IP range?
2. Needle swing during purge or breath: does needle drop about 10-20 psi then recover immediately and remain stable?
3. Lockup/Creep: is the needle stopping (locking-up) or drifting higher (creep) after a breath or purge? Does the needle continually creep up after 1-2 hours or so under pressure or does it lock up before then within the manufacturer-specified range?

The procedure to run the test, as I understand it [and with my questions in CAPS], would be

1. Put the IP gauge under pressure.
2. Observe the initial reading to see if it falls within the manufacturer- specified range and whether it remains stable [OVER HOW LONG A PERIOD SHOULD I WAIT TO OBSERVE CREEP?].
3. Purge 2nd stage (or take a breath) [WHICH IS BETTER, PURGING OR TAKING A BREATH?]
4. Observe how low the pressure goes (should go down about 10-20 psi) [Is 10-20 psi CORRECT?]
5. Observe what pressure the needle recovers to and how long it takes to recover (ideally, should be immediate and to initial reading).
6. If recovering to less than the initial reading, observe how long it takes to creep up to the initial reading. If < 5 psi low and < 5 seconds to lockup at initial reading, then OK. [CORRECT?]
7. If recovering to more than initial reading, if locking up within specified range after 5 sec, then OK. [CORRECT?]
8. Observe if IP remains stable for 1-2 hours after purge test. If no creep, or creep locks up within manufacturer-specified range, then OK. [DO I NEED TO OBSERVE CREEP BOTH BEFORE AND AFTER PURGING, OR JUST ONCE? IF ONCE, SHOULD IT BE BEFORE OR AFTER PURGING?]

 

[Dizzi Lizzi]

 

[mi000ke]

OK, I ditched the second part....

 

[tbone1004]

I'll try to make a video tonight on using one. I have one first stage that is creeping a bit that will show you what not to do. Read Reg Savvy, it explains everything

questions.
2. You should observe it immediately after pressurizing
3. doesn't matter and depends on the reg. If using a "normal" second stage I usually tap the purge button. On my Jetstreams the purge is quite violent so I usually take a breath
4. depends on the first stage and the second stage. Hit the purge button from a Jetstream/Xstream on something like a MK2 and it will be quite a steep dropoff. Hit purge on something like an unbalanced cheap octopus on something like a MK25, and it will be almost negligible. On your Atomic you'll have to check the manual, but it should drop a good bit and have a hard lockup immediately.
6. should say in the manual. Most lockup within a second or two. Some designs lockup faster than others.
7. depends on the tolerances of the first stage. Old Poseidons have a wider range in terms of creep and time to lockup than newer ones. I'm sure most regulators are the same. Your atomic should be pretty tight but will allow up to 3psi of drift. Drift is different than creep. One of my first stages for whatever reason is drifting about 10psi right now. It locks up after about 5 minutes at the higher IP so I think I need to polish the bullet in it, but it will lock which is what is important.
8. it shouldn't matter for creep before or after purge. The duration most techs use is less than 5 minutes and you'll see needle movement. If doing at home and you can spare the gauge for 2 hours then go for it, but 5 minutes is enough.

on service intervals. That is 100% up to you on what you do. I know what I do, I know what Atomic recommends for yours and those are conflicting. That is your call to make.

 

[KeithG]

You have a great start, but I suggest that you can make this whole ball-o-wax simpler by separating the concepts of inspection and servicing. You should inspect regularly and then service as required. As a vacation diver I inspect every dive trip (1 to 3 times a year). Service happens every 200 to 300 dives... I am currently in the process of replacing my 30 year old hoses...

If you feel you can perform inspection, you may want to think about performing your own service? As you have been made aware, there are lots of reg failures caused by bad (unneeded?) service.

And yes - my perfectly functioning regs have been screwed up by a LDS service tech...more than once - shame on me!

P.S. My answers based upon a Sherwood Piston first stage are:
2: Creep can be instantaneous
3: Purging and breathing are the same
4: 10 PSI on my regs
6: instantaneous
7: WTF?

 

[KeithG]

You have a great start, but I suggest that you can make this whole ball-o-wax simpler by separating the concepts of inspection and servicing. You should inspect regularly and then service as required. As a vacation diver I inspect every dive trip (1 to 3 times a year). Service happens every 200 to 300 dives... I am currently in the process of replacing my 30 year old hoses...

If you feel you can perform inspection, you may want to think about performing your own service? As you have been made aware, there are lots of reg failures caused by bad (unneeded?) service.

And yes - my perfectly functioning regs have been screwed up by a LDS service tech...more than once - shame on me!

P.S. My answers based upon a Sherwood Piston first stage are:
2: Creep can be instantaneous
3: Purging and breathing are the same
4: 10 PSI on my regs
6: instantaneous
7: WTF?

And for those peeps that like to service their own regs maybe it will be helpful if I provide a better explanation of my recent experience with what I call "instantaneous creep"?

I believe that many people see a slow change of the IP pressure over time. Hence the term creep. This instability is most often blamed on a seat issue. I have never seen this. My piston regs lock up and stay stable in under a second.

So I recently became a bit confused when I saw an IP of 180psi (reg still breathed just fine). This occurred in under a second (well too fast for me to notice). So I assumed a piston spring issue and started screwing with the shims - BUT I "knew" this was wrong since as the spring weakens you add shims to raise the pressure. Removing shims to lower the IP to compensate for a spring that got stronger (yes - stupid idea?) had exactly zero effect.

Flipping the seat (I had to scrounge for a paper clip) and with all the spring shims back in place gave me a normal IP of 140. It locked up instantly and did not creep. So a high IP was a seat problem and not a spring problem.

I have no idea how / if this translates to a diaphragm reg.

 

[fmerkel]

Creep doesn't much matter if it's diaphragm or piston, it's still creep. In MY experience the pistons are somewhat more likely to creep, but then my experience is a Scubapro MK20 which seems more prone to this problem than some others. That reg is more touchy than anything else in my stable. My diaphragms lock up immediately and solid as do my Sherwood pistons.

A tad of creep is no real problem. In use your next breath will immediately 'reset' the IP. If it doesn't creep much in 5" I consider it good to go. I personally wouldn't bother with a 2 hour test.
If the creep is pronounced/rapid you have an issue that needs to be dealt with whatever the regulator.

Be aware that inexpensive IP gauges are not reference instruments. OTOH there is a bit of slop in the IP setting in real life. Your IP gauge becomes YOUR reference to keep track of YOUR regs.
A shop may be willing to test yours against their reference gauge so you can know how much it's off. Or, just get your reg tested, then check it immediately with your gauge. Depending on the reg the IP can be somewhat different across the tank pressure range.

 

[Dizzi Lizzi]

OK, I ditched the second part....

Shoot, I can't figure out what you edited. Its a great question, and thanks to everyone who is helping you (us!!)

 

[Lorenzoid]

Creep doesn't much matter if it's diaphragm or piston, it's still creep. In MY experience the pistons are somewhat more likely to creep, but then my experience is a Scubapro MK20 which seems more prone to this problem than some others. That reg is more touchy than anything else in my stable. My diaphragms lock up immediately and solid as do my Sherwood pistons.

I got pounced on in another thread for repeating some nugget I had been told in my reg service class to the effect that piston regs tend to get out of tune more quickly than diaphragm regs. One reply called it "nonsense."

 

[tbone1004]

Shoot, I can't figure out what you edited. Its a great question, and thanks to everyone who is helping you (us!!)

he removed the last bit asking about when he should service them