JPS588738B

PURPOSE:To exhaust even dissolved gas of high solubility efficiently and sufficiently, by extracting the dissolved gas in a liquid by reciprocating the piston of a reciprocal piston device by the difference in pressure between a vacuum and air. CONSTITUTION:Vacuum pump 10 is put into operation to bring cylinder chamber 7a, deaeration container 1, and gas sample tubes 14a and 14b into prescribed vacuum states; and three-way valve 9 is changed over to exclude the flow among cylinder chamber 7a, gas sample tubes 14a and 14b, and vacuum pump 10, and selector 3 is opened to flow electric insulating oil in sample oil collector 4 into deaeration container 1, where it is stirred by stirrer 2. Stirring separates dissolved gas, which is stored in cylinder chamber 7a and sample chambers 14a and 14b. With valve 5 closed, differential pressure piston device 20 is put into operation to move piston 7b of reciprocal piston device 7 to left, feeding the dissolved gas to sample chambers 14a and 14b. Next, valve 8 is closed and after piston 7b is moved to right, valve 5 is opened, thereby exhausting the dissolved gas again. This operation is repeated for sufficient deaeration.