Meg cold diving - QC4 leak

tibby · 2nd January 2008, 01:53

Ok, so it's been stinking cold in my neighborhood lately but this never stopped a respecting diver from diving, right?. This morning we all set out to do an ice/slush dive in a balmy 8degF wheather. It turned out we couldn't get to the water and turned to a local warm water spot instead.
Long story short, when I turned my Meg O2 cylinder on, unit having been sitting in the back of my covered truck bed in ambient temp for a couple of hours, a noisy gas leak hiss made itself present. It turned out it came from the QC4 connector (O2 hose to the head) and the more I moved the fitting/hose the worse it got. I looked inside the female part where the o-ring is and it was there so I figured it's just too rigid from the cold considering it worked fine during the predive check. I decided to keep it disconnected until I got the Meg warmed up a bit in the 90deg F water I was about to dive in (geothermal spring). Sure enough, after it warmed up, the damn QC4 worked just fine even when shaken and abused.
I completed my dive with no more QC4 problems but it makes me think whether the QC would've stopped leaking in 35degF water during the ice dive
in the original plan. I doubt it, but I'm glad I didn't find out under the ice.
A few questions spring to mind:
1) Has anyone experienced this before?
2) Has anyone tried to replace the o-ring inside the fitting? I'm just curious as my Meg is only 4 months old so it shouldn't need a new one yet.
3) Has anyone replaced the QC4 with a different fitting? I'm sure ISC chose the odd QC4 for good reason but it seems cold environment wasn't one.
I will try to figure out how cold it needs to be in order for it to start leaking and post what I learn.
Tibby

jhaaja · 2nd January 2008, 06:51

I used QC6 fittings through out last winter with my BOV, never had any of those problems. Sounds odd...

JH

**wedivebc** · 2nd January 2008, 12:20

Hey Tibby,
Sounds to me like a bit of water froze prior to the dive preventing the QC4 from amking a good seal. It would have probably thawed when you hit the water had it not leaked before hand. I doubt the problem would have started once you began the dive.

tibby · 2nd January 2008, 14:18

Quote: (Originally Posted by wedivebc)

Hey Tibby,
Sounds to me like a bit of water froze prior to the dive preventing the QC4 from amking a good seal. It would have probably thawed when you hit the water had it not leaked before hand. I doubt the problem would have started once you began the dive.

Hi Dave,
Happy New Year!
I know the fitting was bone-dry because the head sat in my basement where I did my predive and from there into the covered truck bed. Also there's no humidity in the air this time of year (maybe 20% or less). I'm almost sure it's because the o-ring got too rigid to seal which also explains why the leak got worse as I was moving the hose iside the fitting.
Tibby

tibby · 2nd January 2008, 14:22

Quote: (Originally Posted by jhaaja)

I used QC6 fittings through out last winter with my BOV, never had any of those problems. Sounds odd...

JH

Hi J,
I'm not familiar with QC6, is it the same as the stock fitting on the Meg? I call it a QC4 because that's what I heard people at ISC call it but I don't know much about the various quick-connects out there.
Tibby

Stephane · 2nd January 2008, 15:22

Hello Tibby,

Here you fill find the data sheet of the QC series from Swagelok: http://www.swagelok.com/downloads/we.../MS-01-138.pdf

tibby · 2nd January 2008, 15:49

Quote: (Originally Posted by Stephane)

Hello Tibby,

Here you fill find the data sheet of the QC series from Swagelok: http://www.swagelok.com/downloads/we.../MS-01-138.pdf

Thanks for the link Stephane. Great info. It seems the o-ring in the QC4 is fluorocarbon. I just have to find out a temp range for these o-rings.
Tibby

zzzzzzzz · 2nd January 2008, 16:07

Quote: (Originally Posted by tibby)

Thanks for the link Stephane. Great info. It seems the o-ring in the QC4 is fluorocarbon. I just have to find out a temp range for these o-rings.
Tibby

Hi Tibby,

Since my O-ring catalogue is never far away, here is the info listed within this precious reference:

Fluorocarbon is indicated as having Fair to Poor resistance to cold. :-O

For cold resistance, silicone is the best, followed by Fluorosilicone, Ethylene propylene, Nitrile, SBR, polyurethane,...

The temperature range chart does recommend Fluorocarbon down to -31F or -35C. There could be a tolerance issue with the fittings, although Swagelok tend to be good quality.

z

Stephane · 2nd January 2008, 16:09

In this paper: http://www.swagelok.com/downloads/we...MS-CRD-QC1.pdf
it clearly states:

Quote:

Couple and uncouple quick-connects at room temperature.

tibby · 2nd January 2008, 16:19

I just learned some more interesting stuff from the Swagelock data sheet (link provided above by Stephane).
It appears the Meg uses the QC4 with the flow reversed from that suggested by Swagelock (diagram on page 3 in data sheet).
On page 2 under Operation of Swagelock QC: Couple and uncouple QC at room temperature!!!
Also it warns not to couple and uncouple single end shut off QC (like QC4) while under pressure? I do that all the time. It does show however that QC4 is rated to 3000psig when coupled and 250psig uncoupled or during coupling/uncoupling in the table below the diagram so I guess it's OK.

The o-ring that seems to leak on my meg is the stem o-ring shown in the diagram on page 3.
Tibby

2nd January 2008, 01:53	#1 (permalink)
tibby untitled Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: May 2007 Location: Salt Lake City, UT Posts: 335	Meg cold diving - QC4 leak Ok, so it's been stinking cold in my neighborhood lately but this never stopped a respecting diver from diving, right?. This morning we all set out to do an ice/slush dive in a balmy 8degF wheather. It turned out we couldn't get to the water and turned to a local warm water spot instead. Long story short, when I turned my Meg O2 cylinder on, unit having been sitting in the back of my covered truck bed in ambient temp for a couple of hours, a noisy gas leak hiss made itself present. It turned out it came from the QC4 connector (O2 hose to the head) and the more I moved the fitting/hose the worse it got. I looked inside the female part where the o-ring is and it was there so I figured it's just too rigid from the cold considering it worked fine during the predive check. I decided to keep it disconnected until I got the Meg warmed up a bit in the 90deg F water I was about to dive in (geothermal spring). Sure enough, after it warmed up, the damn QC4 worked just fine even when shaken and abused. I completed my dive with no more QC4 problems but it makes me think whether the QC would've stopped leaking in 35degF water during the ice dive in the original plan. I doubt it, but I'm glad I didn't find out under the ice. A few questions spring to mind: 1) Has anyone experienced this before? 2) Has anyone tried to replace the o-ring inside the fitting? I'm just curious as my Meg is only 4 months old so it shouldn't need a new one yet. 3) Has anyone replaced the QC4 with a different fitting? I'm sure ISC chose the odd QC4 for good reason but it seems cold environment wasn't one. I will try to figure out how cold it needs to be in order for it to start leaking and post what I learn. Tibby __________________ Does the voice of reason change when you add helium to the mix?...hmm
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2nd January 2008, 06:51	#2 (permalink)
jhaaja Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Mar 2005 Location: Finland Posts: 867	Re: Meg cold diving - QC4 leak I used QC6 fittings through out last winter with my BOV, never had any of those problems. Sounds odd... JH
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2nd January 2008, 12:20	#3 (permalink)
wedivebc FIGJAM Current Rebreather/s: Megalodon Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Other CCR Join Date: Feb 2005 Location: Vancouver Island BC Canada Posts: 1,355	Re: Meg cold diving - QC4 leak Hey Tibby, Sounds to me like a bit of water froze prior to the dive preventing the QC4 from amking a good seal. It would have probably thawed when you hit the water had it not leaked before hand. I doubt the problem would have started once you began the dive. __________________ Cheers, Dave.... Man is the only animal burdened with the knowledge he will eventually die
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2nd January 2008, 14:18	#4 (permalink)
tibby untitled Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: May 2007 Location: Salt Lake City, UT Posts: 335	Re: Meg cold diving - QC4 leak Quote: (Originally Posted by wedivebc) Hey Tibby, Sounds to me like a bit of water froze prior to the dive preventing the QC4 from amking a good seal. It would have probably thawed when you hit the water had it not leaked before hand. I doubt the problem would have started once you began the dive. Hi Dave, Happy New Year! I know the fitting was bone-dry because the head sat in my basement where I did my predive and from there into the covered truck bed. Also there's no humidity in the air this time of year (maybe 20% or less). I'm almost sure it's because the o-ring got too rigid to seal which also explains why the leak got worse as I was moving the hose iside the fitting. Tibby __________________ Does the voice of reason change when you add helium to the mix?...hmm
(Offline)

2nd January 2008, 14:22	#5 (permalink)
tibby untitled Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: May 2007 Location: Salt Lake City, UT Posts: 335	Re: Meg cold diving - QC4 leak Quote: (Originally Posted by jhaaja) I used QC6 fittings through out last winter with my BOV, never had any of those problems. Sounds odd... JH Hi J, I'm not familiar with QC6, is it the same as the stock fitting on the Meg? I call it a QC4 because that's what I heard people at ISC call it but I don't know much about the various quick-connects out there. Tibby __________________ Does the voice of reason change when you add helium to the mix?...hmm
(Offline)

2nd January 2008, 15:22	#6 (permalink)
Stephane Hey! Ho! Let's go! Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Nov 2005 Location: Nantes - France Posts: 716	Re: Meg cold diving - QC4 leak Hello Tibby, Here you fill find the data sheet of the QC series from Swagelok: http://www.swagelok.com/downloads/we.../MS-01-138.pdf __________________ Stéphane Hammer-rEvo powered!
(Online)

2nd January 2008, 15:49	#7 (permalink)
tibby untitled Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: May 2007 Location: Salt Lake City, UT Posts: 335	Re: Meg cold diving - QC4 leak Quote: (Originally Posted by Stephane) Hello Tibby, Here you fill find the data sheet of the QC series from Swagelok: http://www.swagelok.com/downloads/we.../MS-01-138.pdf Thanks for the link Stephane. Great info. It seems the o-ring in the QC4 is fluorocarbon. I just have to find out a temp range for these o-rings. Tibby __________________ Does the voice of reason change when you add helium to the mix?...hmm
(Offline)

2nd January 2008, 16:07	#8 (permalink)
zzzzzzzz New Member Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Dec 2006 Location: Earth Posts: 69	Re: Meg cold diving - QC4 leak Quote: (Originally Posted by tibby) Thanks for the link Stephane. Great info. It seems the o-ring in the QC4 is fluorocarbon. I just have to find out a temp range for these o-rings. Tibby Hi Tibby, Since my O-ring catalogue is never far away, here is the info listed within this precious reference: Fluorocarbon is indicated as having Fair to Poor resistance to cold. :-O For cold resistance, silicone is the best, followed by Fluorosilicone, Ethylene propylene, Nitrile, SBR, polyurethane,... The temperature range chart does recommend Fluorocarbon down to -31F or -35C. There could be a tolerance issue with the fittings, although Swagelok tend to be good quality. z __________________ z
(Offline)

2nd January 2008, 16:09	#9 (permalink)
Stephane Hey! Ho! Let's go! Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Nov 2005 Location: Nantes - France Posts: 716	Re: Meg cold diving - QC4 leak In this paper: http://www.swagelok.com/downloads/we...MS-CRD-QC1.pdf it clearly states: Quote: Couple and uncouple quick-connects at room temperature. __________________ Stéphane Hammer-rEvo powered!
(Online)

2nd January 2008, 16:19	#10 (permalink)
tibby untitled Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: May 2007 Location: Salt Lake City, UT Posts: 335	Re: Meg cold diving - QC4 leak I just learned some more interesting stuff from the Swagelock data sheet (link provided above by Stephane). It appears the Meg uses the QC4 with the flow reversed from that suggested by Swagelock (diagram on page 3 in data sheet). On page 2 under Operation of Swagelock QC: Couple and uncouple QC at room temperature!!! Also it warns not to couple and uncouple single end shut off QC (like QC4) while under pressure? I do that all the time. It does show however that QC4 is rated to 3000psig when coupled and 250psig uncoupled or during coupling/uncoupling in the table below the diagram so I guess it's OK. The o-ring that seems to leak on my meg is the stem o-ring shown in the diagram on page 3. Tibby __________________ Does the voice of reason change when you add helium to the mix?...hmm
(Offline)

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