| 摘要 |
PROBLEM TO BE SOLVED: To make a liquid level variation in a safe, simple and accurate state by converting a physical value having temperature dependency into an electric signal, dipping half of a sensor formed in an optimal linear shape in cryogenic liquid, converting the electric signal into a temperature variation and then measuring the same. SOLUTION: Gas is sealed in a hollow hermetically sealed pipe, which is in contact with the phase of a constant temperature T1 . The hollow hermetically sealed pipe is vertically dipped by half in the liquid phase of a constant temperature T2 not equal to the temperature T1 . A pressure is P1 when the hollow hermetically sealed pipe is dipped in the liquid phase up to the height h1 of a liquid level, and pressure is P2 when the hollow hermetically sealed pipe is dipped in the liquid phase up to a height h2 (h1 >h2 ,Δh=h1 -h2 ) (P2 >P1 if the temperatures are T1 >T2 ). If a pressure is P when the liquid level is changed to h1 -Δx,Δx=Δh(P-P1 )/(P2 -P1 ) is obtained. From this value, the vertical variationΔx of the liquid level is calculated. If the inner side section area of the hollow hermetically sealed pipe is known, P2 is calculated fromΔh and P1 .
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