| 摘要 |
PURPOSE:To prevent dehydrated solid matter in a material to be sprayed from sticking to a valve seat by supporting an annular member made of rubber or the like on the upper surface of an enlarged diameter stepped part formed in the outer peripheral section of the valve seat. CONSTITUTION:A ball valve element 2 is disposed in a valve chamber 1 formed therein with a valve seat 3. An annular member 5 made of rubber or the like is supported on the upper surface of an enlarged diameter stepped part 4' formed in the outer peripheral section of the valve seat 3. The valve element allow a material to be sprayed which is a mixture of water, cement, stone powder and the like to pass and shuts off the same. In this phase, the pressure in the valve chamber 1 is repeatedly increased and decreased so that the annular member 5 repeatedly expands and contracts. With this arrangement, a separated and sticking part in the material to be sprayed, which is dehydrated and settled is liberated due to expansion of the annular member during pressure drop, and is discharged into the valve chamber 1, thereby it is possible to prevent solid matter from sticking to the valve seat in growth. |
