In the making of an inflatable toy ball (think of a basketball), a check valve is used to assist the user in the inflation of the ball by preventing backflow of inserted air. Is this check valve made of any metalic parts (such as conventional check valves) or is it all plastic? Also, what type of valve is it? Is there a maximum pressure this type of check valve can sustain before becoming damaged?
Depends on the design - some just use a soft plastic tube that collapses in on itself to seal. That is why some inflating kits have long needle adaptors amongst others in them tapered or parallel.
The maximum pressure a check valve could withstand IMHO is probably far greater than the material used for that ball itself. So, if you over pressurise it then it bursts, usually from the weakest point, and from what i have seen near the seam but not the valve failing first.
It depends on valve design and the application needs.Can ben matal or teflon lined,like PFA lined ball check valve for corrsive applications.