Correct method to test diaghragm first stage after completing annual service

[rsingler]

Among the Tips N' Tricks for diaphragms is one test I was taught that has proved invaluable, but it is before you complete your service, not after.
servicing Hog D1x compared to Apeks DST
In this post, and as detailed in the Scubapro Mark 17 Manual, I recommend you test your HP seal before you add the diaphragm. As an upstream valve, a diaphragm regulator doesn't have to be fully assembled to hold air pressure. What this technique requires, and the SP manual describes, is that you assemble the high-pressure side of the reg first. Many manuals specify placing the pin hat, diaphragm, spring and cap before you assemble the HP side. There is no reason that you can't assemble the HP seat assembly first. This allows you to pressurize your regulator and check for leaks before you've spent all the time putting the rest together.

This test has special value when you're first starting out with diaphragm repair, and may scratch a HP seat and not discover the leak you created until after you've put all that work into reassembly. It also is valuable with some regs that have acquired a reputation for variability in the quality of their HP seats. It's nice to know you have a seal with those regs before you put in any more time. In any case, don't sweat it that the manual says you have to do it in a different order; HP side first works with every diaphragm first stage that I can recall.

There's one final reason to do it this way (true confessions). On a few older style diaphragms, you are supposed to lower the half-assembled reg onto the HP assembly and pin, to keep all the parts together. The HP spring comes under tension just after the pin goes into the hat. Well, a long time ago, I "followed the instructions" without much experience, felt what I thought was spring resistance and proceeded to screw the HP assembly into the bottom of the regulator. It didn't go. Upon disassembly, I found that I'd missed the hole in the hat under the diaphragm, and then bent the pin against the seat as I screwed it in against what I thought was spring pressure. Oops!
This method, on the other hand, allows you to test your seat, then lightly drop the pin in from the diaphragm side, so that particular mistake can't happen.

 

[rsingler]

Can you describe what was included in your basic technician courses for Mares and Cressi and how long those courses were?

Already having certs for multiple mfrs, I enrolled in a (two and a half hour) Cressi course at DEMA two years ago. Got the certificate. But OMG!
One, Cressi's pretty impressive for having all manufacture in-house, including plastic molding. Minimal outsourcing. Good on them!
Two, they are dedicated to making service easier for the technician. Well, look out!

You've serviced for years? You think you know how to disassemble a standard-looking reg?
Man, the plastic hinges and tabs that "don't need tools" to disassemble are imaginative, but really easy to break in a Cressi.
And we covered literally a dozen different regs in two hours. And the handouts are not detailed service manuals like you might expect. So when you forget "the trick" to removing that exhaust tee, you're at risk for breaking a part, or wasting time just thinking about it.

If you want to service Cressi, don't count on the service technician's course. Start there, for sure. But unless you're willing to spend lots of slow time teaching yourself, better work alongside someone who's been doing Cressi for awhile, especially on the second stage side. It won't take long to get up to speed. But in the meantime, you may save your shop some $$ for the parts you broke along the way. Jes' sayin'.

 

[JackD342]

Already having certs for multiple mfrs, I enrolled in a (two and a half hour) Cressi course at DEMA two years ago. Got the certificate. But OMG!
One, Cressi's pretty impressive for having all manufacture in-house, including plastic molding. Minimal outsourcing. Good on them!
Two, they are dedicated to making service easier for the technician. Well, look out!

You've serviced for years? You think you know how to disassemble a standard-looking reg?
Man, the plastic hinges and tabs that "don't need tools" to disassemble are imaginative, but really easy to break in a Cressi.
And we covered literally a dozen different regs in two hours. And the handouts are not detailed service manuals like you might expect. So when you forget "the trick" to removing that exhaust tee, you're at risk for breaking a part, or wasting time jsut thinking about it.

If you want to service Cressi, don't count on the service technician's course. Start there, for sure. But unless you're willing to spend lots of slow time teaching yourself, better work alongside someone who's been doing Cressi for awhile, especially on the second stage side. It won't take long to get up to speed. But in the meantime, you may save your shop some $$ for the parts you broke along the way. Jes' sayin'.

Yeah, broke one a couple months ago rushing for a customer. Probably everyone needs to break just one to learn.
And yes, they need a native English speaker to review the translations from Italian in the manuals.

 

[JackD342]

Already having certs for multiple mfrs, I enrolled in a (two and a half hour) Cressi course at DEMA two years ago. Got the certificate. But OMG!
One, Cressi's pretty impressive for having all manufacture in-house, including plastic molding. Minimal outsourcing. Good on them!
Two, they are dedicated to making service easier for the technician. Well, look out!

You've serviced for years? You think you know how to disassemble a standard-looking reg?
Man, the plastic hinges and tabs that "don't need tools" to disassemble are imaginative, but really easy to break in a Cressi.
And we covered literally a dozen different regs in two hours. And the handouts are not detailed service manuals like you might expect. So when you forget "the trick" to removing that exhaust tee, you're at risk for breaking a part, or wasting time jsut thinking about it.

If you want to service Cressi, don't count on the service technician's course. Start there, for sure. But unless you're willing to spend lots of slow time teaching yourself, better work alongside someone who's been doing Cressi for awhile, especially on the second stage side. It won't take long to get up to speed. But in the meantime, you may save your shop some $$ for the parts you broke along the way. Jes' sayin'.

Also, few if any special tools. Yippee!
Except for that one hard to find hex wrench size in the BCD inflator...

 

[Couv]

I recommend you test your HP seal before you add the diaphragm. As an upstream valve, a diaphragm regulator doesn't have to be fully assembled to hold air pressure. What this technique requires, and the SP manual describes, is that you assemble the high-pressure side of the reg first.

I was hoping somebody (you, @rsingler ) was going to post that. It's a sequence not found in most manuals. After installing the hp components, plug the HP ports and slowly pressurize with full tank pressure. Add a few drops of water to the intermediate chamber and look for bubbling. If OK, empty out the water, add the pin and top hat disc and give it a little press to blow the remaining moisture and accomplishes another leak check.

Edit: Ooops! Speaking of putting the cart before the horse, if I had clicked on rsingler's link I would have seen he mentioned all that in another thread.

 

[rsingler]

Steps 8-11.
They don't mention the water, but it makes leaking air bubbles easier to see than hear.