positive and negative tests

paulcross · 8th July 2007, 21:08

Hi everyone.

Can someone possibly help ,i have finally fitted the dome upgrade kit on my unit,Problem is when i pull a negative to pull down the dome it is hard to seat ,i followed the instructions to the letter ,as extra safety for myself i always perform a positve on the unit to ensure that the lungs stay inflated .There is no problem on the negative side ,you can leave the unit for ages and on opening the mouthpiece you get a sucking sound ,great ,but performing a positve you cannot inflate the lungs all you hear is air escaping from the lower part of the dome from the o ring.
Hope you can help .

Paul.

iani · 8th July 2007, 21:19

You can't do a decent positive test unless you blank off the OPV, as you need to remove the blank before diving what does that prove? I suspect you are hearing the OPV releasing the gas. You should have been told this on the MOD1

Make sure you are putting lots of grease on the dome O-ring, it should then seat easily and the neg test should be good.

Ian

paulcross · 8th July 2007, 21:48

Quote: (Originally Posted by iani)

You can't do a decent positive test unless you blank off the OPV, as you need to remove the blank before diving what does that prove? I suspect you are hearing the OPV releasing the gas. You should have been told this on the MOD1

Make sure you are putting lots of grease on the dome O-ring, it should then seat easily and the neg test should be good.

Ian

Hi Ian

when the dome seats properly you can hear the overpressure valve kicking in the difference is that the lungs will not stay inflated even before the opv kicks in ,will try extra grease on the o ring .

Cheers Paul

***Decodiver*** · 9th July 2007, 09:08

Quote: (Originally Posted by iani)

You should have been told this on the MOD1

He was.........

As Ian has mentionned your O-ring sounds like it is not seated properly Paul, hope you get it sorted.

Cheers,

Dave.

Phil · 9th July 2007, 09:18

Quote: (Originally Posted by paulcross)

Hi Ian

when the dome seats properly you can hear the overpressure valve kicking in the difference is that the lungs will not stay inflated even before the opv kicks in ,will try extra grease on the o ring .

Cheers Paul

I have also found that it is a bit more difficult to put the dome since the upgrade. Just make sure that you push it down to the max so that the dome side are in contact with the o'ring. Then by doing a neg it should be enough to suck the dome down, give it a little push at the same time if needed!

From you comment above it sounds like you may have a leak (hole) on one of the CL. I would remove them and test them separately. Do a pos test in water using the mouth piece hose. For one of the CL you will need an extra hose attachment (Green if I remember correctly)

Cheers,

Drmike · 9th July 2007, 09:54

Quote: (Originally Posted by Phil)

I For one of the CL you will need an extra hose attachment (Green if I remember correctly)

,

actually you dont (although I agree it is far easier with one) You can still find leaks in the field if you havent got/missplaced that adapater.

You can use the hose without the threaded collar (as the bore size is the same the o-rings will seal against the inner bore of the CL connector (in other words take off the outer threaded ring off the hose end and just push the hose end into the CL connector.

Its not easy and it can take a bit of a knack to do it. It helps if you just gently hold the 1st o-ring against the CL connector as square as you can then 'suck' it fully in by pulling a vaccum through mouthpiece.

Once the o-rings are sucked/pushed in you can keep/test the vaccuum on the CL.

To find leaks using the -ve instead of +ve test: With the neg roll a little tiny bit of water in the lung around the inner edge of the lung and you will see/hear bubbles being drawn in through any holes. Mark the spot then after drying cover the spot, the rest of the lung, your hands, your feet, the ships table, your bedsheets and your brand new Nikon D200 in Aqualseal

You dont have to shave your head to perform this trick - but it may help

***Decodiver*** · 9th July 2007, 10:00

Also don't forget that the dome upgrade kit is meant to be used with the original, thinner dome o-ring.

Not the later, thicker one.

Cheers,

Dave Cooper.

paulcross · 9th July 2007, 21:31

Quote: (Originally Posted by Decodiver)

Also don't forget that the dome upgrade kit is meant to be used with the original, thinner dome o-ring.

Not the later, thicker one.

Cheers,

Dave Cooper.

Hi Dave.

Great to hear from you again,My unit is no 88 ,as you remember .I am using the original o ring that the unit came with, does that mean i need a thinner o ring as i got the unit in march 07

Take care Paul.

***Decodiver*** · 10th July 2007, 09:38

Quote: (Originally Posted by paulcross)

Hi Dave.

Great to hear from you again,My unit is no 88 ,as you remember .I am using the original o ring that the unit came with, does that mean i need a thinner o ring as i got the unit in march 07

Take care Paul.

Hi Paul,

I just gave Jason a call at the factory and he has assured me you have the thinner O-ring, meant to be used with the Dome Upgrade Kit.

How's that for service.

Stay safe buddy,

Dave.

IN468 · 10th July 2007, 09:42

The original O-RIng of my No35 was 5,3 mm

I changed it to a 5,7mm oring (not from CCRB)

now with the upgrade kit installed the original 5,3mm is still too small

i feel very save with the 5,7mm O-Ring

8th July 2007, 21:08	#1 (permalink)
paulcross New Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Oct 2005 Location: uk Posts: 15	positive and negative tests Hi everyone. Can someone possibly help ,i have finally fitted the dome upgrade kit on my unit,Problem is when i pull a negative to pull down the dome it is hard to seat ,i followed the instructions to the letter ,as extra safety for myself i always perform a positve on the unit to ensure that the lungs stay inflated .There is no problem on the negative side ,you can leave the unit for ages and on opening the mouthpiece you get a sucking sound ,great ,but performing a positve you cannot inflate the lungs all you hear is air escaping from the lower part of the dome from the o ring. Hope you can help . Paul.
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8th July 2007, 21:19	#2 (permalink)
iani Nefarious Activist Current Rebreather/s: Ouroboros Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: Middlesex, UK Posts: 334	Re: positive and negative tests You can't do a decent positive test unless you blank off the OPV, as you need to remove the blank before diving what does that prove? I suspect you are hearing the OPV releasing the gas. You should have been told this on the MOD1 Make sure you are putting lots of grease on the dome O-ring, it should then seat easily and the neg test should be good. Ian
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8th July 2007, 21:48	#3 (permalink)
paulcross New Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Oct 2005 Location: uk Posts: 15	Re: positive and negative tests Quote: (Originally Posted by iani) You can't do a decent positive test unless you blank off the OPV, as you need to remove the blank before diving what does that prove? I suspect you are hearing the OPV releasing the gas. You should have been told this on the MOD1 Make sure you are putting lots of grease on the dome O-ring, it should then seat easily and the neg test should be good. Ian Hi Ian when the dome seats properly you can hear the overpressure valve kicking in the difference is that the lungs will not stay inflated even before the opv kicks in ,will try extra grease on the o ring . Cheers Paul
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9th July 2007, 09:08	#4 (permalink)
*Decodiver* Administrator Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jan 2005 Location: Geneva Posts: 2,181	Re: positive and negative tests Quote: (Originally Posted by iani) You should have been told this on the MOD1 He was......... As Ian has mentionned your O-ring sounds like it is not seated properly Paul, hope you get it sorted. Cheers, Dave. __________________ CCR/OC Trimix Instructor Trainer CCR Training to Mixed Gas in Switzerland, France, UK & Germany on Megalodon/COPIS-Megalodon/KISS/Sport KISS/Ouroboros/rEvo/Inspiration/Evolution/Sentinel www.zerogravitydiving.com Rebreather World Terms & Conditions
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9th July 2007, 09:18	#5 (permalink)
Phil Custom Title Allowed! Current Rebreather/s: Megalodon Ouroboros rEvo Other CCR Other Rebreather/s: Inspiration Classic Inspiration Vision Evolution Megalodon rEvo Other CCR Join Date: May 2005 Location: Geneva-Switzerland Posts: 172	Re: positive and negative tests Quote: (Originally Posted by paulcross) Hi Ian when the dome seats properly you can hear the overpressure valve kicking in the difference is that the lungs will not stay inflated even before the opv kicks in ,will try extra grease on the o ring . Cheers Paul I have also found that it is a bit more difficult to put the dome since the upgrade. Just make sure that you push it down to the max so that the dome side are in contact with the o'ring. Then by doing a neg it should be enough to suck the dome down, give it a little push at the same time if needed! From you comment above it sounds like you may have a leak (hole) on one of the CL. I would remove them and test them separately. Do a pos test in water using the mouth piece hose. For one of the CL you will need an extra hose attachment (Green if I remember correctly) Cheers, __________________ Phil __________________ CCR/OC Instructor CCR Training to Mixed Gas in Switzerland, France, UK & Germany on Megalodon/KISS/Ouroboros/rEvo/Inspiration/Evolution/Sentinel www.zerogravitydiving.com
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9th July 2007, 10:00	#7 (permalink)
*Decodiver* Administrator Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jan 2005 Location: Geneva Posts: 2,181	Re: positive and negative tests Also don't forget that the dome upgrade kit is meant to be used with the original, thinner dome o-ring. Not the later, thicker one. Cheers, Dave Cooper. __________________ CCR/OC Trimix Instructor Trainer CCR Training to Mixed Gas in Switzerland, France, UK & Germany on Megalodon/COPIS-Megalodon/KISS/Sport KISS/Ouroboros/rEvo/Inspiration/Evolution/Sentinel www.zerogravitydiving.com Rebreather World Terms & Conditions
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9th July 2007, 21:31	#8 (permalink)
paulcross New Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Oct 2005 Location: uk Posts: 15	Re: positive and negative tests Quote: (Originally Posted by Decodiver) Also don't forget that the dome upgrade kit is meant to be used with the original, thinner dome o-ring. Not the later, thicker one. Cheers, Dave Cooper. Hi Dave. Great to hear from you again,My unit is no 88 ,as you remember .I am using the original o ring that the unit came with, does that mean i need a thinner o ring as i got the unit in march 07 Take care Paul.
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10th July 2007, 09:38	#9 (permalink)
*Decodiver* Administrator Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jan 2005 Location: Geneva Posts: 2,181	Re: positive and negative tests Quote: (Originally Posted by paulcross) Hi Dave. Great to hear from you again,My unit is no 88 ,as you remember .I am using the original o ring that the unit came with, does that mean i need a thinner o ring as i got the unit in march 07 Take care Paul. Hi Paul, I just gave Jason a call at the factory and he has assured me you have the thinner O-ring, meant to be used with the Dome Upgrade Kit. How's that for service. Stay safe buddy, Dave. __________________ CCR/OC Trimix Instructor Trainer CCR Training to Mixed Gas in Switzerland, France, UK & Germany on Megalodon/COPIS-Megalodon/KISS/Sport KISS/Ouroboros/rEvo/Inspiration/Evolution/Sentinel www.zerogravitydiving.com Rebreather World Terms & Conditions
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10th July 2007, 09:42	#10 (permalink)
IN468 Custom Title Allowed! Current Rebreather/s: Ouroboros Other Rebreather/s: Inspiration Classic Join Date: Feb 2006 Location: Bavaria Posts: 141	Re: positive and negative tests The original O-RIng of my No35 was 5,3 mm I changed it to a 5,7mm oring (not from CCRB) now with the upgrade kit installed the original 5,3mm is still too small i feel very save with the 5,7mm O-Ring
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