Height sensor for liq. in tank - esp. liquefied hydrocarbon in underground tank, using wt. lifted through liq. by cable drum, and measuring torque needed to rotate drum

摘要

Inside the tank is a vertical tube contg.a wt. which is fixed to the bottom end of a flexible cable, and normally rests on the base of the tank. The top part of the cable is wound on a drum, so the wt. can be lifted upwards at a constant speed. The time at which the wt. is lifted off the tank base, and the time at which the wt. emerges from the surface of the liq., are measured. The difference between the two times indicates the length of cable lifted through the liq. and therefore the height of the latter. The wt. pref. consists of a bell located round a stationary piston functioning as a brake, so a clear signal is obtd. when the bell leaves the base of the tank. The time difference is prf. established by monitoring the torque on the motor driving the cable drum. Accurate measurement of the vol. of a liq. in a tank is obtd.