Plymer coating in basketball to prevent air leaking

[Felipe28]

Hello,

I use special balls (thicker than a regular basketball but with the same characteristics) for hydraulic engineering purposes. These balls must sometimes be inflated at high pressures (more than 70 psi) and then be put inside a pressure vessel connected to a pump line which will contain water under high pressures (200 psi or more). Sometimes this water pressure will vary (hydraulic oscilations or transients) making these balls expand and contract following these variations (the air inside the balls will act as a buffer against high and negative pressures in the water, threfore protecting the pipe).

The question finally is: Can somebody recommend me a special polymer that can be used as a coating surrounding the polybutadiene of the ball to prevent the air to leak through the material? Or maybe manufacture the ball entirely on this polymer.

 

[patprimmer]

Look at air hoses that are rated to over 70psi.

You will notice they are fibre reinforced. That is for a reason.

Regards
Pat
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[Compositepro]

Why are you not using the products that are designed for your application? These are metal tanks with a bladder inside known as expansion tanks or pressure dampers.

 

[btrueblood]

...many/most of which are made with fabric-reinforced diaphragms.

 

[Demon3]

Yes, there is a brilliant coating available from a company called InMat

http://www.inmat.com/

I've tested the stuff and it has amazing impermeability to air. In fact it was so good that we had to recalibrate our permeability machine to be able to measure it. It's a water based dispersion you just spray on.

They have already commercialized their coating for an application similar to yours. They used it inside tennis balls to keep the air pressure in. I'm not sure but I bet they are polybutadiene too!

Good luck,

Chris

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[Felipe28]

Compositepro: you are right, there are tanks with a bladder or diaphragm inside. The balls are a invention of my own, and is pattented. The idea is that the balls do the same work as the bladder but since we have many balls inside the tank it is much more reliable than depending on a unique bladder not to fail. The diaphragm also loses air with the time so it needs constant supervision.

Demon3: I appreciate a lot your information, will take a look and let you know if it ultimately works for me.

 

[Felipe28]

Patprimmer: I will also look at your information. Thanks!

 

[Demon3]

I spoke to the CEO of InMat and relayed your request. Call them and ask to speak to Harris Goldberg. He had comments on what material you should use and on the coating to apply.

Good luck,

Chris

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[Felipe28]

Demon3, I had already sent an email to the technical department but I appreciate your contact. That product makes me be more optimistic about air leakage through the material (gotta worry about the air valve too) even though I am getting to know it and don´t its price yet.

Thanks a lot

 

[patprimmer]

My concern was obviously about bursting strength when the tank has no pressure. 70 psi is a lot for a non reinforced elastomer.

Regards
Pat
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[Felipe28]

patprimmer, I understand your concern. That´s why the balls are specially made with thicker materials on all layers. According to some informal tests we made, it could withstand more than 120 psi of inflating pressure.