John C. Hollemans is the Proprietor of Contrex Consulting and a Chemical Engineer. He has a post graduate degree in Control Engineering from the University of Manchester, UK. Mr Hollemans spent almost fifteen years with Imperial Oil Ltd. (Esso) in Sarnia, Ontario, Canada. He developed a number of Advanced Process Control applications using Esso’s proprietary Generalized Supervisory Programming System and taught process control at Exxon Research & Engineering in Florham Park, New Jersey, USA. A few years before leaving the company he was the leader of the Plant Computing System design team. These kinds of systems are now found in most modern refineries and chemical plants. After becoming an independent consultant in 1990 he held several long term advisory positions with Cegelec’s COMSIP Division in Rueil-Malmaison, France and IBM Nederland in Utrecht, The Netherlands. He also worked as an Expert Witness for several US law firms dealing with product malfunction suits in the area of instrumentation and controls. Now he devotes most of his time teaching first class process control courses.