Problems with negative and postive test

Soren Thomsen

Personally I find 15mins to short. I usually set up my rig the night before and make the neg. test and I'm used to find the convoluted hoses scrunched the next morning. Otherwise 45mins - 1 hour will satisfy me...(the drive to the divesite or boat)

I tried looking it up briefly in the manual and could only find that a pos. test should last 40mins.

Cheers

Soren

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Johnny Christensen

I tried everything from 5 minutes to 48 hours of negative test on my unit.
The times where it could hold a negative for only 5min, had only a cupfull additional water in the exhale lung compared to when it was sealing perfectly.
I have to admit to going in once when it barely could do 2min. In a two hour shallow dive I did get about 2½ liters. Scrubber was still dry, but I won't be doing that again.

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Mark Chase

Sorry if this is a teaching to suck eggs type comment but i didnt read about you trying it,


A spray bottle (I use an old window cleaning spray) with 1/2" of washing up liquid in it and filled with tap water. Put the unit in positive then spray all the joints, mouthpiece, T piece, scrubber lid, hose feeds, OPV, ADV and inject buttons. Even the first stages and leeks are quickly evident, even tiny leeks. This has not only shown up loop problems but also 0 ring failures on the pivoting turrets of the first stage.

When traveling/livaboards etc its a simple and very efficient way of finding leeks with no additional baggage weight as they always have washing up liquid laying around somewhere.

ATB

Mark Chase

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johnnied

Not at all Mark

Actually, I was recommended to do this and did so, but probably not as "scientifically" as I should have done. The thing is, I was looking in the wrong place when I tried this. doh!

Still, like I said, I've gone from being a complete novice to knowing quite a lot about loop integrity in a short space of time.

johnnied

I prefer the sound of 45 minutes on the way to the dive site. Wouldn't you be putting uneccessary strain on the system by holding a neg over night? In any case, surely, that's just showing off? I've been advised routinely not to maintain the neg for more than 15 minutes. Obviously, if you're having problems you'll need to hold it for longer to make sure that there are no slow leaks and give you a bit more confidence.

johnnied

I hope you don't all think I'm over patronising my own thread, but incase anyone's interested, I've come to the conclusion that the main source of my problems were the dil and O2 manual inflators. If you over-tighten them the inner reverse threads can become loose. If you do get a leak on the neg test, you can get weazing sounds (not to be mistaken with Tinnitus!) the origin of which can be a little tricky to locate. Make sense, or am I away with the fairies? Certainly, the 13ml allen key seems to have been the answer to my problems.

John