You guys have an interesting thread going. I tried to respond to some of the smart points brought out earlier.
that's really interesting dan.
if what you say is true than the kite companies could fix these problems by doing a flash sear of the valves right before they go on the kites, what you can do is after the valves have been formed and plasticizer added, you heat sear them so that the outer micrometers of the valve lose their plasticizer . . .
Edt, that's a good idea, shows you're thinking. We thought that might work as well and have tested it. The issue is that the entire pvc valve has plasticizer that will eventually migrate out. Even if you are successful removing plastizer from the surface it will quickly return....so you're only delaying the inevitable.
but maybe there is a production reason why a heat searing treatment won't work (maybe it would deform the valves.
or maybe instead of making the valves out of PVC with plasticizer added they could make the valves out of polyurethane (which is what the bladders are) and add hardener instead of softener
This has been done. A major company offered valves out of polyurethane in 2007 and another kite company did it in 2011 and the valves dry out and crack within the first year. Polyurethane valves usually have a cloudy yellow tint to them and the yellow becomes more noticeable as they age. Valves didn't fall off but they couldn't handle everyday life.
In any case it looks like the basic problem is that kite manufacturers have no control over the actual valve production they are using valves meant for beach balls, inflatable mattresses and rafts, and adapting them to their own use instead of developing a specific research and development project to produce a better valve.
Think of plasticizer wicking like water wicks. When you weld pvc to pvc there is very little migration as both parts have plasticizer and there is no draw from one to the other. For this reason your $3 beach ball doesn't lose the valve.
In kite applications, the plasticizer is drawn out of the pvc valve by the pressure sensitive adhesive (think our 'peel and stick' valves) or polyurethane (think your standard OEM bladder). Why can't we do pvc bladders then? Well, that was done in 2010 by a Chinese factory without giving any notice to several kite brands. The pvc bladders would quickly develop micro tears all over them and as soon as you patched one hole it developed another. Lot's of free bladder sets have been sent out to a handful of 2010 kites that had the vinyl bladders.
there's absolutely no question this is a problem that could be solved if you hire a engineer and throw some money at it.
I won't disagree with you because I think anything is possible if you spend enough time (and that equals money) trying to figure something out.
We have spent the last 2.5 years developing and testing a new approach that has finally materialized into a working product. We appreciate this discussion and we'd like to send some free samples to anyone who's posted before us on this thread if they private message me (not you Dan...you're getting a 6 pack and a nice button up shirt with an AIRTIME logo because you said such pretty things about us). We'll send to a US address only.
Let me introduce the Valve Trap. The Valve Trap sandwiches a valve between two 4” diameter foam discs with a highly specialized adhesive that can tolerate plasticizers. The foam is soft enough to conform to any irregularities in the valve (think the ridges on the top of the valve base from the RF die) so it seals nicely. Also the valve has contact on double the surface area (top of valve base and bottom valve base). The Valve Trap then provides a 4” diameter base with a 'peel and stick' adhesive that will adhere to any bladder.
Why are we going with a 'peel and stick' and not a weld? As we all know, as soon as one air channel develops the valve starts to leak and there is no way to get it to re-seal. With our new adhesive it's always tacky (even after being assaulted by plasticizers) so it can maintain a seal.**
We've been testing in a lab oven since 2010 to find the best setup available. We had one round of samples go into an assortment of kites one year ago in Puerto Rico. Using the combined information we finalized the product and have just recently send out real world samples to a handful of our customers in the worst locations possible.
Here are the instructions from the packaging:
Here is a link to our facebook video introducing it: http://www.facebook.com/photo.php?v=460819870619200
Hope I answered some questions for you.
**Our assembled bladders using OEM spec polyurethane also use the same system with a white "donut" over the valve.