| 摘要 |
PROBLEM TO BE SOLVED: To simplify an airtightness measuring device by eliminating a gas flow meter.SOLUTION: An airtightness measuring device is for an object when a first differential pressure between a first pressure inside the object and an installation environment atmospheric pressure is equal to a set differential pressure. The airtightness measuring device includes: a tank for encapsulating a gas of a second pressure; a flow rate adjustment valve for adjusting a gas flow rate between a tank and the object according to a deviation between the first differential pressure and the set differential pressure; a pressure gauge for outputting a first signal when the pressure inside the tank is a third pressure set value between the first pressure and the second pressure and outputting a second signal when the pressure inside the tank is a fourth pressure set value closer to the first pressure than the third pressure; a timer counter for counting an elapsed time between the time occurrences of the first signal and the second signal; and an estimation part for calculating the airtightness from the elapsed time, the third pressure, the fourth pressure, and a tank volume. The second pressure is a pressure in which the differential pressure between the second pressure and the set environmental atmospheric pressure has the same code as the first differential pressure and the absolute value becomes much larger. |
