A few years ago, the process of selecting a mixer for most applications was straight- forward. When increased demand required an increase in production, process engineers were naturally inclined to choose the type of mixer that had worked before in the same application. When they began talking to equipment manufacturers, their questions focused on capacity, auxiliary equipment, projected delivery and price. Many tested equipment before signing a purchase order. But they were mainly exercising “due diligence” - they were simply looking for proof that the mixer would work. The selection process is more complex today, because the capabilities of the most widely used mixers have expanded steadily during the last decade.