自動高圧液柱圧力計の研究試作

抄録

An automatic manometer with digital counter has been developed with the purpose to measure the pressure0-10000mmHg (0-13.6kg/cm²) absolute with an accuracy less than 0.05% and to establish the standard of pressure. This manometer can measure both 1600mmHg and 3200mmHg absolute pres sures at the same time it measures the pressure near 10000mmHg absolute. As it is impossible to measure pressure with a single 10meter liquid column, this manometer has five columns, each 2.3meters high, and takes new summation methods to handle high pressure. In order to divide 10000mmHg absolute pressure into five columns, the manometer has an orifiec-series system which is in parallel with the column series. Gas flows from the pressure source through the orifice series, giving a differential pressure. to the both sides of each orifice. The orifices are adjustable needle valves and if they are adjusted ade quately, each column gives approximately equal readings. If fluid flow is very small, the perssure source will not be affected by the manometer. Three of the columns, called the high pressure side, measure 60% of inlet pressure, while the other two columns, the low pressure side, measure the remaining 40%. The high pressure columns are precision bore 18-8 stainless steel tube, while the low pressure columns are precision bore glass tube. The upper end of the lowest pressure column is sealed with a: “Torricellian”, vacuum. To detect the meniscus of the liquid column, a phototransistor sensing element is used for the glass tubes and a differential transformer with u-metal is used for the 18-8 stainless steel tubes. The output of the sensing elements is fed through the servo-ampilfier to the servometer which tracks the liquid surface by the zero method and simultaneously, manometer height will be indicated digitally by acounter through a gear train mechanism. This manometer can measure pressure with an accuracy of 0.025%, actually twice as, accurate as that of 0.05% appeared in the specifications. If more accurard standard is available, this automatic manomater is believed to show better data.