START LOAD REDUCING DEVICE OF VACUUM DEVICE USING FLOW CONTROL VALVE

摘要

PURPOSE:To carry out the load reduction at the starting stably by furnishing a flow control valve having a valve body, which is driven by bellows to be driven by the inner-outer pressure difference, in a pipe leading from a vacuum vessel to a rotary pump for exhaustion of the fluid in the vacuum vessel. CONSTITUTION:Before a rotary pump is started, the pressure inside and outside bellows 5 as well as the pressure in a vacuum vessel shall be approx. atmospheric, wherein the bellows 5 are put eccentric to the right by a spring 9, and a valve body 10 is in full closed condition. When this rotary pump is started, the fluid on the line situated on the side nearer the pump than the valve body 10 is first sucked to cause sink of the intra-pipe pressure on the vacuum vessel side and the fluid pressure in the bellows 5. When the force due to the pressure difference between inside and outside of the bellows 5 is enlarged by the resilience of the spring 9, the bellows 5 are contracted against the force of the spring 9, and the valve body 10 is opened through a rod 7 and a con. rod 14. This increases the rate of flow to be sucked toward the pump, and inside of the vacuum vessel the fluid will be sucked until the specified degree of vacuum is attained.