The use of knowledge-based systems can aid an engineer or client in configuring a hydraulic valve for design or order placement. Such a system was developed for placing orders for one particular type of directional control valve from one particular company. The order developed was in terms of the manufacturer's code. Turbo Prolog was used for building the system. The system was built as an example of a tool for use in ordering this particular type of valve and also to evaluate the use of such a system as an element in a valve design system.