Electrical measurement of absolute or differential pressure - is by mercury in glass tube having transparent metallic coating to form variable capacitor in conjunction with dielectric tube

摘要

The pressure measuring system uses a capacitive detector which is sensitive to the length of a column of liq. A conducting liq. (1) form s the liq. column in a dielectric tube (2). The tube has on at least a part of its exterior surface, a conducting coating (3). This coating (3) is not in contact with the liq. (1). Two electrodes (5, 7) are respectively connected to the conducting coating (3) and the liq. conductor (1) to form the two electrodes of the variable capacitor so formed. The conducting coating (3) is transparent so as to permit direct visual observation of the length of the column of liq. the liq. conductor (1) is mercury an the dielectric tube is of glass. The conducting covering is a thin metallic transparent deposit.