PURPOSE: To permit partial replacement with a barrel having liquid flowing holes having different size in case of replacement or when a side plate is worn- out by forming grooves on the side surfaces of a pair of end plates and fitting and fixing the side plate of a cylinder which is inserted between lateral cross- pieces and thus constituting a barrel cylinder in built-in system.

CONSTITUTION: A barrel cylinder 1 is of built-in type and is constituted of the end plates 11 and 11 which form the both sides of the cylinder 1, a plurality of lateral crosspieces 12 which connect two opposed end plates 11 and 11, cylinder plate 14 inserted and supported between the crosspieces, and a closing door 15. Liquid flowing holes are formed on the whole surface of the door 15 and the cylinder plate 14, and a plurality of such doors and cylinder plates each having different opening area ratio, shape of hole, size, etc. are reserved, and can be assembled through replacement to the proper opening area in accordance with use, processing method, an article to be treated, etc. When the closing door 15 or the cylinder plate 14 is worn out after the use for a long period, only the door or the cylinder plate is replaced to a new article, and the barrel cylinder can be used again.