Question reg makes vibrating noise

[Lorenzoid]

I have a HOG D1 (diaphragm first stage) that makes a sort of vibration. Any idea what is the likely cause? When I inhale normally on the second stage, the vibration is a few Hz (like "tat-tat-tat"), and when the LP inflator is used, the vibration frequency increases--makes sense, but what causes this?

It's sort of an academic question, as I'm going to do a complete service on the reg, and I'm sure that will fix the issue. But if it could be a damaged part, it would be educational for me to look for it as I disassemble the reg.

 

[rsingler]

I'll send you a couple of spring pads.
I cut them myself when I run out.
As I recall, 9/16" OD, 3/8" ID, ~10/1000" thick.

But the frequency you describe is really too low for a harmonic. There is nothing that oscillates at what? 1-4Hz? How fast exactly with a medium breath?

Interesting that it's flow related...

 

[rsingler]

So here's a Cressi. Similar to HOG except that HOG has a separate passage via the IP compartment to the balancing area behind the poppet shaft. And there's no removable volcano.

I think we can all visualize the tiny spring coils around the balance chamber "singing" in the HP airflow from the tank.

But what could be clicking at 2-4Hz in that flow path???
Does it happen ALL the time? Or only intermittently?

 

[James79]

Could something be catching/binding in the balance chamber (i.e. debris or a scratch) causing the seat stem to catch? I'm just spitballing, but that would cause a lag in the IP starting to recover, but an instant recovery... and followed by another lag (i.e. the seat doesn't open until IP drops X amount caused by the first quarter second of inhale, then opens abruptly recovering IP followed by the next quarter second to get the IP to drop.... resulting in a 4 hz "vibration")

Just a stupid idea (unless it's right, then it's a great idea!).

Respectfully,

James

 

[rsingler]

Could something be catching/binding in the balance chamber (i.e. debris or a scratch) causing the seat stem to catch? I'm just spitballing, but that would cause a lag in the IP starting to recover, but an instant recovery... and followed by another lag (i.e. the seat doesn't open until IP drops X amount caused by the first quarter second of inhale, then opens abruptly recovering IP followed by the next quarter second to get the IP to drop.... resulting in a 4 hz "vibration")

Just a stupid idea (unless it's right, then it's a great idea!).

Respectfully,

James

Interesting thought. Only problem I can see is that that mechanism implies intermittent valve closure for IP to keep varying. And during a breath or purge, valve is open continuously. But good analysis! I like the "catching on opening" part, but can't figure out what's making the 2nd thru 50th click...

 

[James79]

Interesting thought. Only problem I can see is that that mechanism implies intermittent valve closure for IP to keep varying. And during a breath or purge, valve is open continuously. But good analysis! I like the "catching on opening" part, but can't figure out what's making the 2nd thru 50th click...

If it's a fixed mechanism causing it to catch, couldn't it result in a situation as follows:
IP set at 145 (made up number for argument's sake)
debris or flaw in balance chamber causes seat to not open until IP drops to 120 (second made up number)
IP recovers to set point before closing (due to opening abruptly and going "over" momentarily)
which then resets the "catch" holding it closed until dropping to 120, and cycle repeats.

Or I could be on crack.

 

[Luis H]

My first guess is poor lubrication of the HP O-ring.

Added:
Poor lubrication can cause anything from very minor binding to O-ring pinching and many degrees of friction fluctuation... static friction to dynamic friction can cause chattering, etc.

Most of the behaviors with poor lubrication are predictable, but not always and they can vary.


I would assume this would have become much more common with some of the new (non-silicone) lubricants.

 

[Nemrod]

A Winter Eve, First Stage Woes

Came an issue this way

A knocking

Since what the OP was describing

Came along like a ticking or clicking

Was trying to think of what might be

Sneaking a binding or sticking

But might see

Taking it apart

Before it leaves the OP

A sucking and getting nothing!

Ever more

James

 

[Lorenzoid]

Thanks, Rob (and others). I hooked it up to a tank today and of course it seems to be operating fine. It was acting up consistently when I was diving a few days ago, even after diving. I was hoping to actually measure the frequency today. If I had to attempt to quantify it, to the best of my recollection it was somewhere in the range of 3-7 Hz with a normal inhalation, and it definitely increased to a buzzing when I used the power inflator.

I'll report back if I see anything suspicious when I open it up.

 

[greeniguana]

I had a dive rite 1208 that did the chatter thing. IP rapidly oscilated on inhale. Replacing the HP seat and lube on its shaft/oring and under spring fixed it. Those clear mylar spring gaskets sometimes get doubled up on one side, because they get stuck in the adjustment screw cavity.

The newer XT1 manuals call for lube between the diaphragm and spring. Older dive rite 1st stages don't mention it.

 

[rsingler]

I like it, @James79 !
Waiting with bated breath, @Lorenzoid ...


(Bated breath first appeared in Shakespeare's Merchant of Venice in 1605. Using a shortened form of abated, which means "stopped or reduced," the phrase refers to people holding their breath in excitement or fear as they wait to see what happens next.)