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The joys of valves leaking

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Hugh2
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Re: The joys of valves leaking

Postby Hugh2 » Thu Aug 09, 2018 4:08 pm

Valves are starting to come off my 10-year-old Best kites, but otherwise no problems with my 2012 Cabrinha Vector, and my newer Naish Pivots (2015/2016) are just fine. I've used stick-on valve replacements without problems, but it gets pricy to do an entire kite with seven valves, and like MartinO, this year I finally junked a 2008 Best Waroo 12m because the rest of the kite was on its last legs too. Having a main bladder valve let go far out in the ocean is unpleasant - I wrote an account of such an episode on here a couple of years ago, it was a long swim back.

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tegirinenashi
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Re: The joys of valves leaking

Postby tegirinenashi » Thu Aug 09, 2018 4:49 pm

With all that cost cutting, are Switch Labs still in existence? How about valve heat resistance test:
1. Attach 1 lbs or so weight to the valve
2. Gradually raise the ambient temperature
3. Record the temperature at which the valve is detached
It is interesting to know if there is quality variation among different OEM bladder suppliers.

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Re: The joys of valves leaking

Postby Pemba » Fri Aug 10, 2018 11:10 am

For me there are clear differences between different makes. I've had kites where all (12) valves came off by themselves and others of the same age where none came off. The thing with a test like that is that it's probably pointless to do it with new kites and as soon as you're talking about older kites other things come in. Still I think the issue deserves more attention than it seems to get, any test would certainly get my attention..

maxriderkite
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Re: The joys of valves leaking

Postby maxriderkite » Fri Aug 10, 2018 10:07 pm

Thank you all for your inputs and thoughts about it! It's very reassuring to see I'm not the only one frustrated about this issue.
grigorib wrote:
Wed Aug 08, 2018 7:29 pm
jk. it's a lot like masturbation - most people do it
Haha probably one of the best explanations
tegirinenashi wrote:
Thu Aug 09, 2018 4:49 pm
With all that cost cutting, are Switch Labs still in existence? How about valve heat resistance test:
1. Attach 1 lbs or so weight to the valve
2. Gradually raise the ambient temperature
3. Record the temperature at which the valve is detached
It is interesting to know if there is quality variation among different OEM bladder suppliers.
This could be a very interesting test indeed! Especially because this type of issue is never communicated and it can be very hard to see the differences among manufacturers/brands.

Okay got it, 3 struts absolute maximum, valves will always come off after several years or much less, and avoiding hot storage and heat is undeniable.

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GregK
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Re: The joys of valves leaking

Postby GregK » Fri Aug 10, 2018 10:11 pm

The culprit in valve delamination is the plasticizer added to the PVC valves to make them softer and flexible. It's like a molecular-level lubricant that allows the long molecular chains of the PVC to move slightly, allowing a fairly stiff and somewhat brittle plastic to bend and flex easily.

Over time and accelerated by exposure to heat and water, the plasticizer migrates to and dramatically weakens the RF thermally welded bond line between PVC valve and TPU bladder, or in some newer bladders, the PVC valves are bonded to the bladder with a layer of a third material, a hot-melt adhesive. Accumulated plasticizer will weaken both valve attachment methods.

Easy fix you'd think, don't add plasticizer when fabricating the valves. Not possible, as the PVC would be far more prone to cracking, and cracked valves would be common. It's a fairly complex problem to solve, and likely not yet high on the kite developers' priority list.

Pemba
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Re: The joys of valves leaking

Postby Pemba » Sat Aug 11, 2018 7:40 am

GregK wrote:
Fri Aug 10, 2018 10:11 pm
The culprit in valve delamination is the plasticizer added to the PVC valves to make them softer and flexible. It's like a molecular-level lubricant that allows the long molecular chains of the PVC to move slightly, allowing a fairly stiff and somewhat brittle plastic to bend and flex easily.

Over time and accelerated by exposure to heat and water, the plasticizer migrates to and dramatically weakens the RF thermally welded bond line between PVC valve and TPU bladder, or in some newer bladders, the PVC valves are bonded to the bladder with a layer of a third material, a hot-melt adhesive. Accumulated plasticizer will weaken both valve attachment methods.

Easy fix you'd think, don't add plasticizer when fabricating the valves. Not possible, as the PVC would be far more prone to cracking, and cracked valves would be common. It's a fairly complex problem to solve, and likely not yet high on the kite developers' priority list.

Interesting.. On one of my older kites where the valves never came off, they actually all ended up cracking.. I actually gave up trying to get the old valve off to put a new one on and ended up gluing a new valve over the old one. I assumed the crack was caused by UV (so I think avoidable by painting all valves or something). A few months later ALL valves were cracked. Still, Tegirinenashi's idea of finding two compatible materials fo bladders and valves doesnt seem too far fetched.. ?

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Re: The joys of valves leaking

Postby foilholio » Sat Aug 11, 2018 11:23 am

My valves all leak a bit. It never causes me a problem, kites are always full of air.

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Re: The joys of valves leaking

Postby Windigo1 » Sat Aug 11, 2018 7:32 pm

I haven't had a single valve issue in about 6 or 7 years and I own 17 kites and I ride a lot. Years ago I had a lot of issues with my old GK Sonic there was 3 valves per struts and seven struts that was a whole lot of valves many came unglued. I also had issues with my 2012 Blade Triggers one valve became unglued on the beach in Cabarete it was insanely hot and the sand would burn your feet. Leaving your kite in the sun on a beach for hours when it's 45 degree Celsius will do that.. The newer kites have those big larger valves and they are seated over a larger area on the bladder this is probably more resistant the glue will get softer with heat but the larger surface will keep it there without a leak. Or maybe I'm just lucky but all my kites are pretty recent now and a few are foil kites.

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tegirinenashi
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Re: The joys of valves leaking

Postby tegirinenashi » Sun Aug 12, 2018 1:34 am

The valve does neither have to be hard, nor be exposed to ultraviolet. Valve made of TPU can be hot fused into the bladder. Then, insert PVC pipe from inside and clamp it with another PVC pipe from outside:
valve.png


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