OK, now I see that these pumps, at least some, don't have any tubing inside. I used to donate Platelets and their machines had a system where the tubing that transfered the blood into and out of the machine was placed around a cylindrical form and a wheel with five or six rollers squeezed the tubing against a backing plate. When the wheel rotated the rollers rolled against the tube and pushed the fluid along inside the tube. The fluid never touched anything but the inside of the tube. I was informed by one of the nurses that it was a roller pump. And perhaps it was.
But the link you furnished indicates no tubing at all. So now I can understand where the corrosion is coming from. /forums/images/graemlins/cool.gif
Thanks!