JPS588736B

PURPOSE:To degas dissolved gas efficiently and safely by making electric insulating oil into a prescribed vacuum state to separate dissolved gas and by extracting dissolved gas by a piston unit, etc., which reciprocates due to difference between vacuum dependent upon a vacuum pump and an atmospheric pressure and by releasing this gas into a gas sample tube. CONSTITUTION:Piston 7b is moved to the right by differential pressure piston unit 20 to open valves 5, 8 and 9, and cylinder room 7a and gas sample tubes 14a and 14b are connected to vacuum pump 10 to make the inside of them into a vacuum state. After that, three-direction valve 9 is switched to cut off connection to pump 10, and valve 3 is opened to put insulating oil in sample oil pick-up equipment 4 into gas removal vessel 1, and this oil is agitated. Dissolved gas in oil is separated and released and is stored in cylinder room 7a and sample tube 14, and valve 5 is closed to move piston 7b to the left by differential pressure piston unit 20, and gas in cylinder room 7a is transferred to sample tube 14. Next, when valve 8 is closed to move piston 7b to the right, gas dissolved in oil in vessel 1 is released into cylinder room 7a. Then, by repeating this operation, dissolved gas can be degassed sufficiently.