2nd stage suction test

[Ed Palma]

I've got a question for those familiar with this test. Its the one that involves inhaling through a 2nd stage attatched to a closed tank - the purpose of which is to detect possible leaks in either the diaphragm or the exhaust mushrooms. Anyway, my question is: how much suction can be considered adequate? Whenever I perform this test my USD regs, they're all fine and no matter how hard I inhale, I can't get anything in. However, when I tried this with my friend's Beuchat VX10 regs, if I sucked gently, it was fine (no air). However, when I increased suction, the exhaust mushrooms would slightly fold, allowing some air to come in.
I'll be pool testing them tomorrow at my LDS, but in the event that they don't leak, should I still get the valves replaced?

 

[DeepSeaExplorer]

Some exhaust valves are more rigid than others, so gentle suction is in order. There's probably nothing wrong. When it's in the water with the air on, it won't have that kind of suction on it anyway.

The test is most usful for determining if the exhaust valve is leaking causing wet breathing, not so much comparing one reg to another.

 

[redacted]

You don't need much vacuum. Definately not enough to suck the exhaust valve in. I managed to do that once on a wet Scubapro metal 2nd that I was having a little trouble with getting a good seal on the exhaust valve. A little jewlers polish on the seating surface stopped the leak but left it a little slick. I was sucking too hard.

 

[Ed Palma]

Just an update: I tested both regulators that I cleaned and adjusted the other day in 14 feet of water. Neither of them breathed wet in any position, so i guess it IS possible to suck a little too hard when doing this suction test. It must also be due to the shape of the exhauset valves. They aren't the round one's i'm used to, but oblong with twin stems.