Problems with negative and postive test

johnnied · 16th October 2007, 22:47

Hello all

Advice on the following would be much appreciated:

I think my unit has failed both negative and positive tests (although I'm not absolutely sure what actually constitutes a failure).

I suspected that the convoluted hose end o rings were not seating properly so have worked out (finally

) how to take these out and clean them etc and have now hopefully eliminated this as cause of failure.

Unit reassembled and tested. I get a good negative but it doesn't hold and further more, I'm clearly hearing air seeping back into the loop via the over pressure relief valve. On the positive test, it's taking two good pushes of the manual dil addition button, before the valve operates again.

So the next question is do I disassemble this (are there o rings involved in this part of the system?), clean and reassemble or do I have a faulty valve. I read somewhere that there had been a batch of faulty valves, Does anyone know anything about this?

John

jhaaja · 17th October 2007, 07:55

At first you could try to clean the valve by filling the inhale lung with water and then running the water out through the pressure relief valve.

JH

johnnied · 17th October 2007, 21:23

Quote: (Originally Posted by jhaaja)

At first you could try to clean the valve by filling the inhale lung with water and then running the water out through the pressure relief valve.

JH

I'll give it a try - presumably you mean the exhale counterlung?

jptaylor9 · 17th October 2007, 21:41

Quote: (Originally Posted by johnnied)

So the next question is do I disassemble this (are there o rings involved in this part of the system?), clean and reassemble or do I have a faulty valve.

See diagram, you'll need Rebreather TOOL 5 (I can lend you one) Over pressure exhaust valve spanner.

JT

jhaaja · 18th October 2007, 05:39

Quote: (Originally Posted by johnnied)

I'll give it a try - presumably you mean the exhale counterlung?

Yes, mindfart

Exhale of course.

johnnied · 18th October 2007, 14:12

Quote: (Originally Posted by jhaaja)

At first you could try to clean the valve by filling the inhale lung with water and then running the water out through the pressure relief valve.

JH

OK. Done this and the problem is no better. Actually it's now worse on the positive with a gentle squeeze on the exhale counterlung prompting a rush of air out of the valve while closed!

So aided by Jon's diagram (for which, many thanks Jon) and a Rebreather tool 5, soon to arrive in the post, I'll take it apart, give it a scoosh with some warm water and see if that does the trick.

dave burke · 20th October 2007, 03:08

Why dont you give APD a ring , ask to speak to a service engineer
tell him your problem
they have always been most helpfull when i have phone them
safe diving
dave

johnnied · 22nd October 2007, 15:36

Quote: (Originally Posted by dave burke)

Why dont you give APD a ring , ask to speak to a service engineer
tell him your problem
they have always been most helpfull when i have phone them
safe diving
dave

Hello Dave

I have spoken to them but didn't do so immediately as I knew they'd just got back from the Dive Show. Normally they'd be my first port of call and like you, I've always found them most helpul on the phone.

Still, It's also interesting to see what other people have to offer. I suppose I'm increasing my chances of learning something.

AP say take the valve apart and clean in warm water. Then turn over the seating diapraghm (at least I think that the one they mentioned - another phone call there!) before reassembling. I'm still waiting on a rbtool5 through the post before proceeding.

John

dave burke · 23rd October 2007, 03:35

Hi John
hope you do get it sorted out
please let us know when its working right
safe diving
dave

johnnied · 3rd November 2007, 20:09

Quote: (Originally Posted by dave burke)

Hi John
hope you do get it sorted out
please let us know when its working right
safe diving
dave

Well, you're not truly a rebreather diver till you've had your counterlungs in the bath and finally managed to work out where your loop leak was! There's nothing like having to solve a problem yourself to bring on your knowledge of something. I feel like I've learnt so much about my unit and gained a lot of confidence in terms of taking things apart and putting them back together. Overpressure valve stripped and cleaned. That particular problem solved but still no neg or positive so exhale t piece stripped and replaced. Front loop isolated by means of rear inhale convoluted hose going onto back of exhale tpiece and counterlung dunked in the bath. Hey presto - leak coming from underneath manual O2 inflator. Problem was solved simply by undoing and doing up a couple of times. Not very scientific I know but worked. And proper pos and negs as a result. I'll need to have a go at it with the 13ml allen key but not just now as I'm going diving tomorrow. Having read other people's posts about positive and negative tests, I've always felt it to be a bit of a grey area. Well, it doesn't seem to be quite so grey anymore. Simply, if you don't get a good neg, don't dive.What's a good neg? Convoluted hose remaining scrunched for at least 15 mins but preferably for a good 30 mins.Comments welcome, particularly if you think I'm on the wrong track. John

16th October 2007, 22:47	#1 (permalink)
johnnied New Member Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Vision Join Date: Oct 2006 Location: London Posts: 48	Problems with negative and postive test Hello all Advice on the following would be much appreciated: I think my unit has failed both negative and positive tests (although I'm not absolutely sure what actually constitutes a failure). I suspected that the convoluted hose end o rings were not seating properly so have worked out (finally) how to take these out and clean them etc and have now hopefully eliminated this as cause of failure. Unit reassembled and tested. I get a good negative but it doesn't hold and further more, I'm clearly hearing air seeping back into the loop via the over pressure relief valve. On the positive test, it's taking two good pushes of the manual dil addition button, before the valve operates again. So the next question is do I disassemble this (are there o rings involved in this part of the system?), clean and reassemble or do I have a faulty valve. I read somewhere that there had been a batch of faulty valves, Does anyone know anything about this? John
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17th October 2007, 07:55	#2 (permalink)
jhaaja Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Mar 2005 Location: Finland Posts: 884	Re: Problems with negative and postive test At first you could try to clean the valve by filling the inhale lung with water and then running the water out through the pressure relief valve. JH
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17th October 2007, 21:23	#3 (permalink)
johnnied New Member Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Vision Join Date: Oct 2006 Location: London Posts: 48	Re: Problems with negative and postive test Quote: (Originally Posted by jhaaja) At first you could try to clean the valve by filling the inhale lung with water and then running the water out through the pressure relief valve. JH I'll give it a try - presumably you mean the exhale counterlung?
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17th October 2007, 21:41	#4 (permalink)
jptaylor9 Member Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: London, UK Posts: 318	Re: Problems with negative and postive test Quote: (Originally Posted by johnnied) So the next question is do I disassemble this (are there o rings involved in this part of the system?), clean and reassemble or do I have a faulty valve. See diagram, you'll need Rebreather TOOL 5 (I can lend you one) Over pressure exhaust valve spanner. JT Last edited by jptaylor9 : 7th June 2008 at 11:36.
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18th October 2007, 05:39	#5 (permalink)
jhaaja Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Mar 2005 Location: Finland Posts: 884	Re: Problems with negative and postive test Quote: (Originally Posted by johnnied) I'll give it a try - presumably you mean the exhale counterlung? Yes, mindfart Exhale of course.
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18th October 2007, 14:12	#6 (permalink)
johnnied New Member Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Vision Join Date: Oct 2006 Location: London Posts: 48	Re: Problems with negative and postive test Quote: (Originally Posted by jhaaja) At first you could try to clean the valve by filling the inhale lung with water and then running the water out through the pressure relief valve. JH OK. Done this and the problem is no better. Actually it's now worse on the positive with a gentle squeeze on the exhale counterlung prompting a rush of air out of the valve while closed! So aided by Jon's diagram (for which, many thanks Jon) and a Rebreather tool 5, soon to arrive in the post, I'll take it apart, give it a scoosh with some warm water and see if that does the trick.
(Offline)

20th October 2007, 03:08	#7 (permalink)
dave burke Custom Title Allowed! Current Rebreather/s: Inspiration Vision Other Rebreather/s: Join Date: Dec 2006 Location: kent Posts: 133	Re: Problems with negative and postive test Why dont you give APD a ring , ask to speak to a service engineer tell him your problem they have always been most helpfull when i have phone them safe diving dave
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22nd October 2007, 15:36	#8 (permalink)
johnnied New Member Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Vision Join Date: Oct 2006 Location: London Posts: 48	Re: Problems with negative and postive test Quote: (Originally Posted by dave burke) Why dont you give APD a ring , ask to speak to a service engineer tell him your problem they have always been most helpfull when i have phone them safe diving dave Hello Dave I have spoken to them but didn't do so immediately as I knew they'd just got back from the Dive Show. Normally they'd be my first port of call and like you, I've always found them most helpul on the phone. Still, It's also interesting to see what other people have to offer. I suppose I'm increasing my chances of learning something. AP say take the valve apart and clean in warm water. Then turn over the seating diapraghm (at least I think that the one they mentioned - another phone call there!) before reassembling. I'm still waiting on a rbtool5 through the post before proceeding. John
(Offline)

23rd October 2007, 03:35	#9 (permalink)
dave burke Custom Title Allowed! Current Rebreather/s: Inspiration Vision Other Rebreather/s: Join Date: Dec 2006 Location: kent Posts: 133	Re: Problems with negative and postive test Hi John hope you do get it sorted out please let us know when its working right safe diving dave
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3rd November 2007, 20:09	#10 (permalink)
johnnied New Member Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Vision Join Date: Oct 2006 Location: London Posts: 48	Re: Problems with negative and postive test Quote: (Originally Posted by dave burke) Hi John hope you do get it sorted out please let us know when its working right safe diving dave Well, you're not truly a rebreather diver till you've had your counterlungs in the bath and finally managed to work out where your loop leak was! There's nothing like having to solve a problem yourself to bring on your knowledge of something. I feel like I've learnt so much about my unit and gained a lot of confidence in terms of taking things apart and putting them back together. Overpressure valve stripped and cleaned. That particular problem solved but still no neg or positive so exhale t piece stripped and replaced. Front loop isolated by means of rear inhale convoluted hose going onto back of exhale tpiece and counterlung dunked in the bath. Hey presto - leak coming from underneath manual O2 inflator. Problem was solved simply by undoing and doing up a couple of times. Not very scientific I know but worked. And proper pos and negs as a result. I'll need to have a go at it with the 13ml allen key but not just now as I'm going diving tomorrow. Having read other people's posts about positive and negative tests, I've always felt it to be a bit of a grey area. Well, it doesn't seem to be quite so grey anymore. Simply, if you don't get a good neg, don't dive.What's a good neg? Convoluted hose remaining scrunched for at least 15 mins but preferably for a good 30 mins.Comments welcome, particularly if you think I'm on the wrong track. John
(Offline)

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