jjccr negative pressure test - Page 2

Venomguy · July 15th, 2012, 12:09 PM

Quote: (Originally Posted by marco73)

Hello all

I've tried negative test pressure on my new jjccr (200 min of dive) for all night (12 hours) but does not pass.

The negative test pass only after about 30 mins - 45 mins.

How many time I can consider secure the negative pressure test?

have a nice dive :D

MArco

Negative test is for only about 5 seconds, positve is for a few minutes,

I use to sometimes leave a positive overnight, but not necessary

**Paul Haynes** · July 15th, 2012, 12:30 PM

Quote: (Originally Posted by marco73)

Hello all

I've tried negative test pressure on my new jjccr (200 min of dive) for all night (12 hours) but does not pass.

The negative test pass only after about 30 mins - 45 mins.

How many time I can consider secure the negative pressure test?

have a nice dive :D

MArco

With appropriate precision engineering, machining tolerances, O ring selection etc, the negative loop test should last many hours if not days. However 30 - 45 mins sounds fine considering a 5min test is the pre-dive norm. I would therefore not be overly concerned. Indeed many a CCR diver would be delighted if their neg test lasted that long on their particular unit. Rgds Paul

matt · July 15th, 2012, 01:39 PM

Quote: (Originally Posted by Venomguy)

Negative test is for only about 5 seconds,

LOL, I think you could get 5 seconds with a 2" gash.

Remco · July 15th, 2012, 06:55 PM

So the result of the negative test is ...positive than...

barrygoss · July 15th, 2012, 07:06 PM

I watched a neg test done in less than 30seconds last weekend.
On a Kiss, and it proved a rock solid neg.
The owner connected a digital manometer to the loop via the lp inflate on the wing inflate (just plug in) pulled a neg, watched the reading on the meter, no change, neg test done.
Trouble is digital manometers are ***163;110. But fastest, cleanest most reassuring neg I've ever seen. No watching to see if the loop drops. If the meter doesn't change you've got neg.
Regards
B

Remco · July 16th, 2012, 04:03 PM

On the JJ , you look at the ADV button....
It is that simple... if you need a digital tester for that ...

Ben Field · July 16th, 2012, 04:26 PM

Quote: (Originally Posted by barrygoss)

I watched a neg test done in less than 30seconds last weekend.
B

Good thing too, much longer than that and the stock ADV starts to get floppy on the KISS (over time)

I always wondered about negative and positive tests, why do people do "long" tests?

As a KISS diver a quick test was required but I would pull the neg (or blow the pos) then let the unit stand for 30seconds, if no noticable change give the hoses, DSV, lungs, scrubber and regs and good prod- still holding then it must be all good right? All done in 60secs flat, it might get left a full 2 minutes some times if I was preoccupied.

What does testing for even 5mins prove? IF the leak is so tiny it takes 5min+ to impact a RB loop will you even notice it? (I'm sure someone will come along with an ancedote of how one did just that to prove me wrong...) So okay 5-10minutes but hours and days? Comeon thats just boasting BS surely, it can't have any benefit can it!

IMO the most important thing is not to leave the unit alone, I've seen alot of people do a pos/neg and very carefully back off and inspect the unit from a few ft away almost as if them breathing close to it will cause a leak- I think you need to give the unit abit of a shake and poke around to see if the unit or its hoses position is hiding a leak.

It seems to me this is another source of diving myth (like scrubber durations and CO2 monitors

)

matt · July 16th, 2012, 04:58 PM

I agree with Ben on 5-10 mins. Longer isn't proving much. I'm unconvinced by 30 seconds - not sure that shows much either!

Matt.

Ben Field · July 17th, 2012, 09:52 AM

Quote: (Originally Posted by matthewoutram)

I'm unconvinced by 30 seconds - not sure that shows much either!

I'd never say 30secs was enough but... if you have a leak somewhere the most noticable change will be when the loop is most negative or positive, which in the case of a small leak is in the first few seconds.

On CK we have a heavy BOV, when you pull a neg this is lifted up off the deck by the compression of the breathing hoses, if there is any kind of leak the BOV begins to sink down under its weight. IME if it didn't move in the first 30sec-minute it isn't going to, same with positive, if the lungs, hoses etc aren't taught and full after 30secs its rarely going to change.

30secs isn't enough, but it tells you alot.

Lastly I have seen diver battling to resolve incredible small leaks on the DSV and breathing hoses then they jump in and let in far more water via loose lips and generated spit... makes you wonder what their goal was solving the leak

matt · July 17th, 2012, 10:17 AM

Quote: (Originally Posted by Ben Field)

I'd never say 30secs was enough but... if you have a leak somewhere the most noticable change will be when the loop is most negative or positive, which in the case of a small leak is in the first few seconds.

On CK we have a heavy BOV, when you pull a neg this is lifted up off the deck by the compression of the breathing hoses, if there is any kind of leak the BOV begins to sink down under its weight. IME if it didn't move in the first 30sec-minute it isn't going to, same with positive, if the lungs, hoses etc aren't taught and full after 30secs its rarely going to change.

30secs isn't enough, but it tells you alot.

Lastly I have seen diver battling to resolve incredible small leaks on the DSV and breathing hoses then they jump in and let in far more water via loose lips and generated spit... makes you wonder what their goal was solving the leak

Agreed. Big leak will fail fast, and only a nutter would dive with a big leak.

I've seen units pass 10 mins or more positive and negative with a 1-2" gash in the convoluted hose (it's rubber, it seals).

I've seen someone 80m gas diving the same - few bubbles, about 1/2 cup of water.

Ambient pressure.

Matt.

July 15th, 2012, 12:09 PM	#11
Venomguy New Member Join Date: Apr 2012 Location: PNG Posts: 32 Thanks: 0 Thanked 0 Times in 0 Posts	Quote: (Originally Posted by marco73) Hello all I've tried negative test pressure on my new jjccr (200 min of dive) for all night (12 hours) but does not pass. The negative test pass only after about 30 mins - 45 mins. How many time I can consider secure the negative pressure test? have a nice dive :D MArco Negative test is for only about 5 seconds, positve is for a few minutes, I use to sometimes leave a positive overnight, but not necessary
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July 15th, 2012, 12:30 PM	#12 (permalink)
Paul Haynes CCRX Supporter Join Date: Mar 2012 Location: Scotland Posts: 197 Thanks: 61 Thanked 145 Times in 28 Posts	Quote: (Originally Posted by marco73) Hello all I've tried negative test pressure on my new jjccr (200 min of dive) for all night (12 hours) but does not pass. The negative test pass only after about 30 mins - 45 mins. How many time I can consider secure the negative pressure test? have a nice dive :D MArco With appropriate precision engineering, machining tolerances, O ring selection etc, the negative loop test should last many hours if not days. However 30 - 45 mins sounds fine considering a 5min test is the pre-dive norm. I would therefore not be overly concerned. Indeed many a CCR diver would be delighted if their neg test lasted that long on their particular unit. Rgds Paul __________________ When you dive you enter an alien world, death is evolution's default state; at some point your life support will fail to function correctly, plan on it.
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July 15th, 2012, 01:39 PM	#13 (permalink)
matt New Member Join Date: Apr 2012 Location: London Posts: 1,541 Thanks: 168 Thanked 74 Times in 60 Posts	Quote: (Originally Posted by Venomguy) Negative test is for only about 5 seconds, LOL, I think you could get 5 seconds with a 2" gash.
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July 15th, 2012, 06:55 PM	#14 (permalink)
Remco New Member Join Date: Apr 2012 Location: Netherlands Posts: 161 Thanks: 0 Thanked 0 Times in 0 Posts	So the result of the negative test is ...positive than...
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July 15th, 2012, 07:06 PM	#15 (permalink)
barrygoss CCRx Supporter Join Date: Mar 2012 Location: northampton Posts: 56 Thanks: 11 Thanked 1 Time in 1 Post	I watched a neg test done in less than 30seconds last weekend. On a Kiss, and it proved a rock solid neg. The owner connected a digital manometer to the loop via the lp inflate on the wing inflate (just plug in) pulled a neg, watched the reading on the meter, no change, neg test done. Trouble is digital manometers are ***163;110. But fastest, cleanest most reassuring neg I've ever seen. No watching to see if the loop drops. If the meter doesn't change you've got neg. Regards B
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July 16th, 2012, 04:03 PM	#16 (permalink)
Remco New Member Join Date: Apr 2012 Location: Netherlands Posts: 161 Thanks: 0 Thanked 0 Times in 0 Posts	On the JJ , you look at the ADV button.... It is that simple... if you need a digital tester for that ...
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July 16th, 2012, 04:26 PM	#17 (permalink)
Ben Field New Member Join Date: Mar 2012 Location: Weymouth, UK Posts: 235 Thanks: 23 Thanked 77 Times in 32 Posts	Quote: (Originally Posted by barrygoss) I watched a neg test done in less than 30seconds last weekend. B Good thing too, much longer than that and the stock ADV starts to get floppy on the KISS (over time) I always wondered about negative and positive tests, why do people do "long" tests? As a KISS diver a quick test was required but I would pull the neg (or blow the pos) then let the unit stand for 30seconds, if no noticable change give the hoses, DSV, lungs, scrubber and regs and good prod- still holding then it must be all good right? All done in 60secs flat, it might get left a full 2 minutes some times if I was preoccupied. What does testing for even 5mins prove? IF the leak is so tiny it takes 5min+ to impact a RB loop will you even notice it? (I'm sure someone will come along with an ancedote of how one did just that to prove me wrong...) So okay 5-10minutes but hours and days? Comeon thats just boasting BS surely, it can't have any benefit can it! IMO the most important thing is not to leave the unit alone, I've seen alot of people do a pos/neg and very carefully back off and inspect the unit from a few ft away almost as if them breathing close to it will cause a leak- I think you need to give the unit abit of a shake and poke around to see if the unit or its hoses position is hiding a leak. It seems to me this is another source of diving myth (like scrubber durations and CO2 monitors )
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July 16th, 2012, 04:58 PM	#18 (permalink)
matt New Member Join Date: Apr 2012 Location: London Posts: 1,541 Thanks: 168 Thanked 74 Times in 60 Posts	I agree with Ben on 5-10 mins. Longer isn't proving much. I'm unconvinced by 30 seconds - not sure that shows much either! Matt.
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July 17th, 2012, 09:52 AM	#19 (permalink)
Ben Field New Member Join Date: Mar 2012 Location: Weymouth, UK Posts: 235 Thanks: 23 Thanked 77 Times in 32 Posts	Quote: (Originally Posted by matthewoutram) I'm unconvinced by 30 seconds - not sure that shows much either! I'd never say 30secs was enough but... if you have a leak somewhere the most noticable change will be when the loop is most negative or positive, which in the case of a small leak is in the first few seconds. On CK we have a heavy BOV, when you pull a neg this is lifted up off the deck by the compression of the breathing hoses, if there is any kind of leak the BOV begins to sink down under its weight. IME if it didn't move in the first 30sec-minute it isn't going to, same with positive, if the lungs, hoses etc aren't taught and full after 30secs its rarely going to change. 30secs isn't enough, but it tells you alot. Lastly I have seen diver battling to resolve incredible small leaks on the DSV and breathing hoses then they jump in and let in far more water via loose lips and generated spit... makes you wonder what their goal was solving the leak
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July 17th, 2012, 10:17 AM	#20 (permalink)
matt New Member Join Date: Apr 2012 Location: London Posts: 1,541 Thanks: 168 Thanked 74 Times in 60 Posts	Quote: (Originally Posted by Ben Field) I'd never say 30secs was enough but... if you have a leak somewhere the most noticable change will be when the loop is most negative or positive, which in the case of a small leak is in the first few seconds. On CK we have a heavy BOV, when you pull a neg this is lifted up off the deck by the compression of the breathing hoses, if there is any kind of leak the BOV begins to sink down under its weight. IME if it didn't move in the first 30sec-minute it isn't going to, same with positive, if the lungs, hoses etc aren't taught and full after 30secs its rarely going to change. 30secs isn't enough, but it tells you alot. Lastly I have seen diver battling to resolve incredible small leaks on the DSV and breathing hoses then they jump in and let in far more water via loose lips and generated spit... makes you wonder what their goal was solving the leak Agreed. Big leak will fail fast, and only a nutter would dive with a big leak. I've seen units pass 10 mins or more positive and negative with a 1-2" gash in the convoluted hose (it's rubber, it seals). I've seen someone 80m gas diving the same - few bubbles, about 1/2 cup of water. Ambient pressure. Matt.
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