CHEM-TITE PTFE/PFA LINED-SEVERE DUTY PRODUCTS Hills-McCanna is the USA pioneer and a world leader in the design, production and application of diaphragm valves. First introduced over 50 years ago, Hills-McCanna valves have consistently proven their value in tough applications thru years of reliable service. The Chem-Tite product line has expanded the range of valve designs and services to include butterfly, ball, plug, and ball check valves to handle a variety of fluids and gases, including highly corrosive topic chemicals and abrasive slurries.