Quick question about second stage testing

[InTheDrink]

Hi,

I thought I read in this forum some time back that one test of your second stage when detached from a tank to test for leaks is to suck into the mouthpiece. If you get air coming through then there's a leak.

So I was trying this with my primary second stage the other day and I can get air when sucking it.

Tried my backup and nothing, sucking through it gave me no air.

Tried my new primary second stage (which I'm not using currently) and that too gives me air when I suck it.

So two out of three, including one brand new second stage, gives me air when I suck through it. So am I simply remembering incorrectly and that it is indicative of nothing that I can suck through it?

TIA,
John

 

[jonnythan]

Put your finger over the hose intake

You can pull air in through the valve assembly. Either hook it up to a first stage whose inlet is sealed off with a dust cap or DIN cap and try again, or put your finger over the hose connection on the side of the reg.

 

[eponym]

Do this test with the second connected to a first stage and the first mounted on a tank but the air off. That will rule out sucking air in past the dust cap.

If you can still inhale on a connected second, it's possible the diaphragm isn't seating fully.

-Bryan

 

[ianr33]

Make sure the inlet to the first stage is blocked. (Good dust cap or finger)

You should not be able to suck air from the second stage.If you can something is leaking.Most likely either the exhaust valve or the diaphragm. This could cause it to breathe wet in the water.

Edit: Damn you guys are quick!

 

[Bubbletrubble]

You mentioned that you are doing the test with the first stage not attached to a tank valve.

Are you plugging the inlet on the first stage (with a dust cap, thumb, etc.)? If not, you should be able to draw some air into your second stage.

Think about how the regulator is designed...and what you are trying to test. If you are plugging the first stage inlet and trying to inhale on a second stage, you are testing the air-tight integrity of the system (second stage, LP hose, first stage). What would happen if the second stage diaphragm were seated improperly? What would happen if a second stage exhaust valve malfunctioned? What would happen if you forgot to plug one of the LP ports on the first stage?

A related test can be done by disconnecting the second stage, sticking your thumb in the inlet (where the LP hose connects) and trying to inhale off of the mouthpiece. This checks for air-tight integrity of the second stage alone.

I hope this helps...

 

[InTheDrink]

So thanks to everyone for the RAPID responses. Man you guys pounce!

As expected I was indeed being an idiot. I ticked several of the boxes for what I wasn't testing.

Although the dustcap was on it's not airtight. I removed it and placed my finger over the connection instead and la voila, no air coming through the second stage anymore. I can't find an emoticon for embarrassed....

Thanks for your help. Not something I'll forget again in a hurry

J

 

[LeadTurn_SD]

In addition to the above: Make sure the end of the BC inflator hose is also blocked with your thumb; I've been able to draw air through that hose when attempting to test the 2nd stage...

Really, if it seems like the 2nd stage may be "failing" the vacuum test, the best way to test the 2nd stage is to remove it from the hose, then stick your thumb over inlet to the 2nd stage. That way you've isolated the 2nd stage from everything else.

With the 2nd stage "isolated", you should be able to suck fairly hard and no air should pass through the 2nd stage. If you do hear air passing through, then you need to try to determine where the leak is occuring.

If the 2nd stage "passes" when isolated, you can put the hose back on the 2nd stage (but leave the hose disconnected from the first stage) and try again. This will test the connection between the hose and 2nd stage.

Let us know how it goes.

Best wishes.

 

[cerich]

and if you have a atomic it will suck air because of the seat saving orifice.

Also if you suck too hard you can fold in the exhaust diaphragm and cause leaks

 

[InTheDrink]

In addition to the above: Make sure the end of the BC inflator hose is also blocked with your thumb; I've been able to draw air through that hose when attempting to test the 2nd stage...

Really, if it seems like the 2nd stage may be "failing" the vacuum test, the best way to test the 2nd stage is to remove it from the hose, then stick your thumb over inlet to the 2nd stage. That way you've isolated the 2nd stage from everything else.

With the 2nd stage "isolated", you should be able to suck fairly hard and no air should pass through the 2nd stage. If you do hear air passing through, then you need to try to determine where the leak is occuring.

If the 2nd stage "passes" when isolated, you can put the hose back on the 2nd stage (but leave the hose disconnected from the first stage) and try again. This will test the connection between the hose and 2nd stage.

Let us know how it goes.

Best wishes.

That was my other lesson. I also took the second stage off completely so knew what I'd be testing. Simple but I didn't do it initially. I don't know why I didn't think of this first - tiredness probably, although I'd be pondering the issue for a couple of days.

Cheers,
J

 

[halocline]

and if you have a atomic it will suck air because of the seat saving orifice.

Also if you suck too hard you can fold in the exhaust diaphragm and cause leaks

More specifically, if your alternate 2nd stage has a seat saver (or big leak) you can draw air in your primary through the alternate 2nd stage, down to the 1st stage IP chamber, and back out to the primary 2nd stage. If only your primary has the seat saver, but is still connected to a non-leaking 1st stage, you should not get any air through it. The seat saver only disconnects the seat from the orifice, and sucking on the regulator does the same thing by collapsing the diaphragm.

If your exhaust valve is in good shape, it should hold a pretty decent vacuum, maybe 5" or so of water.