Rebuilding a sealed diaphragm first stage, how many purge cycles?

[JohnN]

This is a HOG D1 sealed (Apex knock-off). How many purge cycles should I do before I call it good? The IP has stabilized at around 120 PSI (at least according to the inexpensive IP gauge).

Is there an approximate number that is considered "optimal" ?

 

[rsingler]

This is a HOG D1 sealed (Apex knock-off). How many purge cycles should I do before I call it good? The IP has stabilized at around 120 PSI (at least according to the inexpensive IP gauge).

Is there an approximate number that is considered "optimal" ?

More than you want to do without wearing out your mouth or wasting a tank of air. Several hundred, minimum.
Alternatively, I just pressurize and walk away. If it's the same in an hour, I'm encouraged. If it's the same in 4 hours, I go to bed. If it's the same in the morning, I'm good to go.

Alternatively, if it's crept 4psi in four hours, I may try again in the morning, when I can look at 1, 4 & 8 hours. If it stabilizes after 4 hours, I'm still good. If it's still creeping another couple psi, then I have to decide whether it's worth tearing it down again to polish the orifice (which is not easy in a D1).

But isn't 120psi slightly below spec? Not really a problem for your balanced second stage, but i thought I'd mention it. Just another 1/4 turn on the hex.
(And as you know, reinstall the environmental seal with the reg pressurized.)

 

[Cdncoldwater]

I don't know HOG but if it holds stable for 10 minutes after you cycle it 6-12 times it's probably good. Some manufacturers have a set amount but Apeks doesn't that I've read or seen and you state this is based on that company. It will change over use but should be within specs. I set Apeks and most others at 135psi for cold waters and they might go up 5-10 psi between rebuilds that I've done (still in spec). Any I've seen higher usually had debris or corrosion issues or a valve damaged likely during assembly or adjustment, which should show up within a few minutes.

 

[rsingler]

I don't know HOG but if it holds stable for 10 minutes after you cycle it 6-12 times it's probably good.

Since this is the DIY forum, this is a good fork in the road for discussion. On basic principle, I don't disagree with @Cdncoldwater in terms of what is acceptable.
Think about what happens with IP creep in between breaths. There's not enough time for IP creep to get to dangerous or to freeflow levels. A bigger concern might be a 90 min long boat ride out to the dive site. If the regs sit there for an hour and a half, will a 0.25"/min IP creep result in a freeflow? After all, that rate is only 2.5 psi creep in the 10 min recommended above. But in 90 min, your reg will have crept from 135 to 157psi. Maybe enough to leak from your second stage.
In other words, it's not a safety issue for your regs, or for your dive when thinking breath to breath. It's maybe a gas loss issue.

So what you accept in DIY service is a function of personal belief. Me? I'm a little OCD. I figure a reg that is designed to seal should seal. Unfortunately, in today's mass production, max profit environment, quality control costs money. My new, expensive Mk25EVO/D420 had 4psi IP creep from the factory, an out of spec IP, and a second stage that freeflowed a tiny bit. Fortunately, I could fix it all. New parts from Scubapro, Poseidon and Atomic all have finishes that are less than perfect. Thank goodness for Micromesh!

Local dive shops often do NOT take the time to fix these little issues before they release a new reg set, and so we ask questions on ScubaBoard like "how much IP drift before lockup is acceptable?"

IMO, the answer is "None!" And that gives us DIY'ers something to do. But @Cdncoldwater is also correct. There's nothing wrong with a little drift that then locks up tight. But me, I just prefer that it's zero, or at least doesn't progress over many hours. Just because I might forget to turn off my tank valve, and I don't want to lose any gas due to my forgetfulness. And maybe because the valve ought to perform as designed.

 

[Jack Hammer]

There's a pretty cool device that cycles 1st and 2nd stages, I forget the name. Basically it's a motor with a cam that purges the 2nd stage via suction, speed is adjustable. When I use it at my buddy's shop I let it run for 5 or so minutes. It puts both stages through a few hundred cycles.

 

[inka]

Jack Hammer>This device:Quick Set - Poppet & Seat Break-In Fixture

 

[Cdncoldwater]

Since this is the DIY forum, this is a good fork in the road for discussion. On basic principle, I don't disagree with @Cdncoldwater in terms of what is acceptable.
Think about what happens with IP creep in between breaths. There's not enough time for IP creep to get to dangerous or to get to freeflow levels. A bigger concern might be a 90 min long boat ride out to the dive site. If the regs sit there for an hour and a half, will a 0.25"/min IP creep result in a freeflow? After all, that rate is only 2.5 psi creep in the 10 min recommended above. But in 90 min, your reg will have crept from 135 to 157psi. Maybe enough to leak from your second stage.
In other words, it's not a safety issue for your regs, or for your dive when thinking breath to breath. It's maybe a gas loss issue.

So what you accept in DIY service is a function of personal belief. Me? I'm a little OCD. I figure a reg that is designed to seal should seal. Unfortunately, in today's mass production, max profit environment, quality control costs money. My new, expensive Mk25EVO/D420 had 4psi IP creep from the factory, an out of spec IP, and a second stage that freeflowed a tiny bit. Fortunately, I could fix it all. New parts from Scubapro, Poseidon and Atomic all have finishes that are less than perfect. Thank goodness for Micromesh!

Local dive shops do NOT take the time to fix these little issues before they release a new reg set, and so we ask questions on ScubaBoard like "how much IP drift before lockup is acceptable?"

IMO, the answer is "None!" And that gives us DIY'ers something to do. But @Cdncoldwater is also correct. There's nothing wrong with a little drift that then locks up tight. But me, I just prefer that it's zero, or at least doesn't progress over many hours. Just because I might forget to turn off my tank valve, and I don't want to lose any gas due to my forgetfulness. And maybe because the valve ought to perform as designed.

@rsingler you make some very good points but I would ask why you are leaving your regulator pressurized on a 90 minute (or any length of boat ride); to me that's a bad practice. I've seen people inadvertently lean stuff against purge buttons, knock a valve or connector etc on boat and shore so leaving it pressurized before donning to enter to me is a bad habit. I work on Scuba Pro and other brands and have seen the same issue you had with new Mk25EVO 1st stages as well and other brands (not nice when a set up turns into a "rebuild" on a new item). At the LDS where I work when we assemble for our customers we check, adjust and verify lock up of IP as well as cracking effort as per the specifications of that regulator and for cold water diving or where it will be used.

I also know that not all LDS are the same and that not all techs put the same level of effort into their work. To me dive gear and diving isn't a place to have a "good enough" attitude and it isn't in the shop I'm at so I'm lucky in that respect. I have seen customers not want to pay for a rebuild but three months later they are back with a creeping or free flowing set of regulators. I wish the industry would train people to service their own and if they chose to go to a shop after that's up to them. Ive squired enough tools and experience now to do mine and my son's gear so I'm happy with that but also enjoy working at my LDS.

 

[Jim Lapenta]

I do between 40 and 50 purges/breaths at 500, 1500, and 3000 PSI. Give or take 200 PSI either way at each setting. If I can do more I will but that has proven to be pretty reliable on the HOG regs I've been servicing over the last 10 years or so.
Occasionally the IP may still drop a few PSI over the next say 4-5 dives as the seat takes a set, but if it does it's no more than 2-3 PSI. That's using say 40 at each pressure.
The initial IP is set at 135 at 3000 PSI and either breathe it or leave it on a pressurized cylinder for a while (an hour is more than enough) it's still going to end up at 132 + which is well within the recommended operating range of 135 +/- 5 PSI.
I have my personal regs set at 131- 133 for the most part.
120 PSI is well below the recommended operating range. The max operating range is technically 125-145 but neither the low or high end should be where the reg is set.

 

[Jack Hammer]

Jack Hammer>This device:Quick Set - Poppet & Seat Break-In Fixture

That looks like the one. It's pretty quick and works great

 

[rsingler]

There's an even more Cadillac version from Scuba Instruments that uses much less air and a much higher frequency (up to 240 cycles per minute) for high volume shops.

Unfortunately, it's over two grand, as I recollect, lol.

@rsingler you make some very good points but I would ask why you are leaving your regulator pressurized on a 90 minute (or any length of boat ride); to me that's a bad practice. I've seen people inadvertently lean stuff against purge buttons, knock a valve or connector etc on boat and shore so leaving it pressurized before donning to enter to me is a bad habit. I work on Scuba Pro and other brands and have seen the same issue you had with new Mk25EVO 1st stages as well and other brands (not nice when a set up turns into a "rebuild" on a new item). At the LDS where I work when we assemble for our customers we check, adjust and verify lock up of IP as well as cracking effort as per the specifications of that regulator and for cold water diving or where it will be used.

I also know that not all LDS are the same and that not all techs put the same level of effort into their work. To me dive gear and diving isn't a place to have a "good enough" attitude and it isn't in the shop I'm at so I'm lucky in that respect. I have seen customers not want to pay for a rebuild but three months later they are back with a creeping or free flowing set of regulators. I wish the industry would train people to service their own and if they chose to go to a shop after that's up to them. Ive squired enough tools and experience now to do mine and my son's gear so I'm happy with that but also enjoy working at my LDS.

It sounds like you and I are on exactly the same page. Of course it's bad practice to leave your set pressurized for long periods on the boat ride. I was just throwing myself under the bus for discussion purposes. A better (more common) example might be the guys that slog up the beach after a rough surface exit and plop down for lunch during their surface interval, only to find when they set up for dive #2 that they forgot to turn off their tank after dive #1. No harm done. When they hear their second stage start to flow from IP creep, they will quickly turn off their tank. But then they'll also wonder what's wrong with their equipment.
It also sounds like you have a quality shop that does what should be done for regs that, as you have confirmed, sometimes come from the factory in suboptimal shape.
Yeah, we're on the same page.

And @JohnN , if @Jim Lapenta says 150 cycles are enough, well, you're hearing it from the horse's mouth. That's all you need.