Since there is a keen demand for resource saving and no pollution in the world, a remarkable advance has been made recently in mechanical pulp, especially TMP (thermomechanical pulp). Much information on TMP is provided globally in the field of research and development. It is undeniable that TMP is more excellent than stone groundwood pulp (GP). So, TMP plants have been constructed and operated in many paper mills in the world. To satisfy the requirement of the pulp and paper industry, we Kumagai Riki developed in 1975 this refiner in collaboration with Japan Pulp and paper Research Institute, Inc. which has advanced pulp preparation technology, based on the conventional KRK normal pressure refiner. Set in the laboratory the same conditions as those in the practical plant operation, and steam chips for a short time, and perform pressurized refining. It features ease of operation and excellent reproducibility.