TBTFZ-31A consists of lid, outer and inner tanks, grid, insulation course, heaters, tube union, water tap, watertight seal, guard and electric control box. It is one of the equipment for testing soundness(expansion) of cement using both Le Chatelier soundness and pat test method. It can control and maintain water temperature automatically through 2 groups of heater. It is one of the necessary device in the labs of cement plants and research units concerned.