INTERNAL PRESSURE CONTROL METHOD OF INCOMPLETE AIRTIGHT SPACE

摘要

PURPOSE:To reduce both the operating frequency of a control valve and the gas consumption by providing a line for continuous supply of the minimum amount of gas against the leakage of gas out of an open air shielding structure and feeding the gas to the amount equal to a steady flow rate of the holding pressure. CONSTITUTION:The open air pressure PO is shielded by an open air shielding structure 1 to hold the gas of internal presure Pin. A gas supply line 3 is connected to the structure 1 via an ON-OFF valve 2. This valve 2 is controlled by a differential pressure gauge 4. While a pipe 3a branched from the line 3 is connected to the structure 1 via a pressure reducing valve 5, a flow rate control valve 6 and a flow rate meter 7. Then a flow rate of such a degree that can maintain the minimum atmospheric pressure difference from the open air is set to the valve 6 in concideration of the gas leakage amount of the structure 1. Then the gas is fed into the structure 1 through the pipe 3a. Furthermore the rise of the pressure PO is detected by the gauge 4. Then the gas is fed into the structure 1 from the valve 2 via the line 3.