+ve and -ve tests

Pierre Farrugia · 19th July 2006, 08:15

Hello all,

My unit does not seem to hold -ve test, crashed hoses for long, that is seconds! +ve pressure is held maybe for a min or 2, when I do +ve test lungs will be rock hard, then then will start reducing hardness! The problem is at the bubble check I don't see any leaks and after the dive I don't find any water, apart from normal condesation ? Is this normal ?

What are your suggestions? I think I will start changing all O rings, I already greased them but does not seem to work!!

Andy M · 19th July 2006, 08:18

Quote: (Originally Posted by Pierre Farrugia)

What are your suggestions? I think I will start changing all O rings, I already greased them but does not seem to work!!

Do you have a BOV on your inspo? I've found that most neg leaks on my kiss have been due to leaking on the BOV.

Andy

Pierre Farrugia · 19th July 2006, 08:32

Quote: (Originally Posted by Andy M)

Do you have a BOV on your inspo? I've found that most neg leaks on my kiss have been due to leaking on the BOV.

Andy

No standard unit and with Shut off valve on ADV

jhaaja · 19th July 2006, 08:41

Quote: (Originally Posted by Pierre Farrugia)

No standard unit and with Shut off valve on ADV

Make sure you have the AVD shut off in closed position. If that does not help just check by listening where the leak could be. On my unit it is 99% of times on one of the shoulder t-piece to hose connections. The other times it has been the original mouthpiece inside o-ring or the manual add buttons have been too loose.

Hope this helps!

JH

Padowan · 19th July 2006, 08:46

On my unit, 99% of the time it fails positive test it's due to a leak around the diaphragm of the ADV, and when it fails negative tests, it's the connections of the hoses to the T-pieces.

Pierre Farrugia · 19th July 2006, 08:54

Quote: (Originally Posted by Padowan)

On my unit, 99% of the time it fails positive test it's due to a leak around the diaphragm of the ADV, and when it fails negative tests, it's the connections of the hoses to the T-pieces.

How you know it's from there? Also what you do about the diaphragm ?

Pierre Farrugia · 19th July 2006, 08:54

Quote: (Originally Posted by jhaaja)

Make sure you have the AVD shut off in closed position. If that does not help just check by listening where the leak could be. On my unit it is 99% of times on one of the shoulder t-piece to hose connections. The other times it has been the original mouthpiece inside o-ring or the manual add buttons have been too loose.

Hope this helps!

JH

What do you do to solve the problem, clean and lub ?

jhaaja · 19th July 2006, 09:06

Quote: (Originally Posted by Pierre Farrugia)

What do you do to solve the problem, clean and lub ?

If the manual add button nipple or valve pin is leaking the best thing is to take it apart, check, clean, lube and put together and test. If the o-rings look bad, you should get the service kit and change the o-rings.

Can you tell more exactly where it is leaking? The button, the hose or?

JH

Padowan · 19th July 2006, 09:17

Quote: (Originally Posted by Pierre Farrugia)

How you know it's from there? Also what you do about the diaphragm ?

I can find the positive leak by blowing the loop up and squirting soapy water all over the place, you will see bubbles from the leak site. If this is the diaphragm, then I strip, clean and re-lube the diaphragm assembly it only takes about 10 minutes - here's some photos of the components that go into the assembly...

If the leak is a negative one, then I usually start off with the t-piece connections, and this usually solves it, hence it being the first place I look. I usually start by loostening the connectors and twisting them back and forth to seat the o-rings, if this doesn't solve it, then I disconnect them, and clean the T-piece barrels and the connectors with a piece of cloth, then put a smear of silicone on the inside of the t-pieces and reassemble - most of the time this will solve it. If not, then I start looking for other places that it could be losing negative.

Mark Wan · 19th July 2006, 09:21

You can also try and identify if it's the front or rear part of the loop leaking. Connect the exhale hose (from above the t-piece) to the inhale t-piece. Then do +ve / -ve tests. Once you've identified and fixed the problem there, you can connect the scrubber inline again, and make sure that's ok too.

I remember seeing the BSAC Inspiration mod1 course notes, where they say that if you remove the t-pieces from the lungs for any reason, you should use silicon sealant (yes, the same stuff used in a bathroom, not silicon grease) to reseat the t-pieces. If you've removed the t-pieces, perhaps this will help?

Another thing which people have suggested is using silicon grease instead of o2 lube on the loop connections. Obviously only use o2 lube on high pressure o2 connections like the o2 reg and the solenoid hose.

Hope this helps
Mark

19th July 2006, 08:15	#1 (permalink)
Pierre Farrugia Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: Malta Posts: 636	+ve and -ve tests Hello all, My unit does not seem to hold -ve test, crashed hoses for long, that is seconds! +ve pressure is held maybe for a min or 2, when I do +ve test lungs will be rock hard, then then will start reducing hardness! The problem is at the bubble check I don't see any leaks and after the dive I don't find any water, apart from normal condesation ? Is this normal ? What are your suggestions? I think I will start changing all O rings, I already greased them but does not seem to work!! __________________ Pierre Farrugia My wife told me " If you don't quit diving I'm going to leave you" My reply " God, I'll miss you" www.atlam.org www.divemed.com
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19th July 2006, 08:18	#2 (permalink)
Andy M Dude Current Rebreather/s: Home Build Other Rebreather/s: Sport Kiss Home Build Join Date: Mar 2005 Location: Cambridge, UK Posts: 428	Re: +ve and -ve tests Quote: (Originally Posted by Pierre Farrugia) What are your suggestions? I think I will start changing all O rings, I already greased them but does not seem to work!! Do you have a BOV on your inspo? I've found that most neg leaks on my kiss have been due to leaking on the BOV. Andy __________________ Know your PO2 at all times
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19th July 2006, 08:32	#3 (permalink)
Pierre Farrugia Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: Malta Posts: 636	Re: +ve and -ve tests Quote: (Originally Posted by Andy M) Do you have a BOV on your inspo? I've found that most neg leaks on my kiss have been due to leaking on the BOV. Andy No standard unit and with Shut off valve on ADV __________________ Pierre Farrugia My wife told me " If you don't quit diving I'm going to leave you" My reply " God, I'll miss you" www.atlam.org www.divemed.com
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19th July 2006, 08:41	#4 (permalink)
jhaaja Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Mar 2005 Location: Finland Posts: 885	Re: +ve and -ve tests Quote: (Originally Posted by Pierre Farrugia) No standard unit and with Shut off valve on ADV Make sure you have the AVD shut off in closed position. If that does not help just check by listening where the leak could be. On my unit it is 99% of times on one of the shoulder t-piece to hose connections. The other times it has been the original mouthpiece inside o-ring or the manual add buttons have been too loose. Hope this helps! JH
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19th July 2006, 08:46	#5 (permalink)
Padowan RBW Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: Exeter, UK. Posts: 524	Re: +ve and -ve tests On my unit, 99% of the time it fails positive test it's due to a leak around the diaphragm of the ADV, and when it fails negative tests, it's the connections of the hoses to the T-pieces. __________________ Padowan The future's bright, the future's Yellow .....for now padowan.net - Latest Video: Scapa Flow Rebreather Diving
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19th July 2006, 08:54	#6 (permalink)
Pierre Farrugia Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: Malta Posts: 636	Re: +ve and -ve tests Quote: (Originally Posted by Padowan) On my unit, 99% of the time it fails positive test it's due to a leak around the diaphragm of the ADV, and when it fails negative tests, it's the connections of the hoses to the T-pieces. How you know it's from there? Also what you do about the diaphragm ? __________________ Pierre Farrugia My wife told me " If you don't quit diving I'm going to leave you" My reply " God, I'll miss you" www.atlam.org www.divemed.com
(Offline)

19th July 2006, 08:54	#7 (permalink)
Pierre Farrugia Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: Malta Posts: 636	Re: +ve and -ve tests Quote: (Originally Posted by jhaaja) Make sure you have the AVD shut off in closed position. If that does not help just check by listening where the leak could be. On my unit it is 99% of times on one of the shoulder t-piece to hose connections. The other times it has been the original mouthpiece inside o-ring or the manual add buttons have been too loose. Hope this helps! JH What do you do to solve the problem, clean and lub ? __________________ Pierre Farrugia My wife told me " If you don't quit diving I'm going to leave you" My reply " God, I'll miss you" www.atlam.org www.divemed.com
(Offline)

19th July 2006, 09:06	#8 (permalink)
jhaaja Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Mar 2005 Location: Finland Posts: 885	Re: +ve and -ve tests Quote: (Originally Posted by Pierre Farrugia) What do you do to solve the problem, clean and lub ? If the manual add button nipple or valve pin is leaking the best thing is to take it apart, check, clean, lube and put together and test. If the o-rings look bad, you should get the service kit and change the o-rings. Can you tell more exactly where it is leaking? The button, the hose or? JH
(Offline)

19th July 2006, 09:17	#9 (permalink)
Padowan RBW Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: Exeter, UK. Posts: 524	Re: +ve and -ve tests Quote: (Originally Posted by Pierre Farrugia) How you know it's from there? Also what you do about the diaphragm ? I can find the positive leak by blowing the loop up and squirting soapy water all over the place, you will see bubbles from the leak site. If this is the diaphragm, then I strip, clean and re-lube the diaphragm assembly it only takes about 10 minutes - here's some photos of the components that go into the assembly... If the leak is a negative one, then I usually start off with the t-piece connections, and this usually solves it, hence it being the first place I look. I usually start by loostening the connectors and twisting them back and forth to seat the o-rings, if this doesn't solve it, then I disconnect them, and clean the T-piece barrels and the connectors with a piece of cloth, then put a smear of silicone on the inside of the t-pieces and reassemble - most of the time this will solve it. If not, then I start looking for other places that it could be losing negative. __________________ Padowan The future's bright, the future's Yellow .....for now padowan.net - Latest Video: Scapa Flow Rebreather Diving
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19th July 2006, 09:21	#10 (permalink)
Mark Wan New Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Nov 2005 Location: Hammersmith, London Posts: 59	Re: +ve and -ve tests You can also try and identify if it's the front or rear part of the loop leaking. Connect the exhale hose (from above the t-piece) to the inhale t-piece. Then do +ve / -ve tests. Once you've identified and fixed the problem there, you can connect the scrubber inline again, and make sure that's ok too. I remember seeing the BSAC Inspiration mod1 course notes, where they say that if you remove the t-pieces from the lungs for any reason, you should use silicon sealant (yes, the same stuff used in a bathroom, not silicon grease) to reseat the t-pieces. If you've removed the t-pieces, perhaps this will help? Another thing which people have suggested is using silicon grease instead of o2 lube on the loop connections. Obviously only use o2 lube on high pressure o2 connections like the o2 reg and the solenoid hose. Hope this helps Mark __________________ newbie inspo vision diver
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