In my Master's Thesis I am presenting a control system renovation of a coating machine which belongs to one of the Hungary's leading pharmaceutical companies. Firstly I studied the standardized explosion protection principles, explosion proof safety tools and methods. Based on the explosion protection knowledge I gathered the increased safety and user requirements which are needed by the renovated control system. I have previously been a member of a similar machine development group, but with that machine we were unable to use flammable coating solvents, so we could overcome many problems using simpler solutions. I designed the modifications to the previous plans and system networks according to the new requirements and implemented the modifications to the software elements. Finally the new system was installed and I designed a testing method to prove that the renovated system meets the safety and user requirements. The testing method result was successful and customers and providers were satisfied.