John Abbott, Weir, Australia, reviews the importance of valve selection in ensuring safe and efficient mining operations.

The quality of valve surgery itself was still relatively crude for both closed- and open-heart techniques. But we made a deal. We would start the project by developing one valve at a time ...

There are four valves in the heart and each one has strong flaps called “leaflets” that control blood flow. Leaflets open to let blood move through the heart and out to the rest of the body. They then ...