VALVE

PURPOSE:To eliminate the difficulty or incapability of valve opening and closing operation due to particulate matter by providing a particulate matter discharge passage to connect a valve body passage formed in the valve box to the downstream passage in the valve body when the valve is in the fully closed position. CONSTITUTION:Valve body 3 is made of a ceramic material highly resistant to wear and the sliding contact parts 2a, 2a of valve box 2 are also made of a similar material. Additionally, the free end of valve body 3 is so formed that the part on the upstream side 1a of the pasage 1 extends beyond the part on the downstream side 1b toward the valve body passage 4b, and a particulate discharge passage 8 is formed to connect valve body passage 4b to the downstream side 1b of passage 1 when in the fully closed position, thereby to suppress the wear of valve body 3 and its sliding contact parts 2a and 2b.