To prevent a decrease in the purity of nitrogen gas due to a leak of compressed air, in a pressure booster of nitrogen gas intensifying a pressure of nitrogen gas by compressed air.
An intermediate chamber 36 between rod packing 35a sealing a rod 35 inserted through a center body 22, an intermediate chamber 68 in a pilot valve 47B for switching a switch valve 28, and an intermediate chamber 85 in a governor 29 for adjusting a secondary pressure of nitrogen gas, are respectively provided. These intermediate chambers are opened respectively to the outside by a passage, and compressed air leaking to a booster chamber side from a drive chamber side and nitrogen gas leaking to the drive chamber side from the booster chamber side are discharged to the outside by these intermediate chambers.
FUKAMACHI KOICHI
YAMAJI MIKIO
