GB325651A - Improvements in or relating to vacuum gauges - Google Patents

Abstract

325,651. Yates, J. A. Jan. 3, 1929. Vacuum gauges.-Comprises a tube with a sealed vacuum end as in a barometer, a liquid or diaphragm movably balanced against the vacuum therein and the vacuum to be measured, and means operated by the movable element to operate one or more indicating or recording instruments, characterized by a relatively short tube and small balancing capacity of the liquid or diaphragm. The form shown in Fig. 1 comprises a U-tube the leg a of which is closed and provided with a vacuum above the mercury b the broader leg e communicating with the vacuum to be measured. A magnetic float c rests on the mercury in the closed leg which is surrounded by a coil d of a self-balancing inductance bridge. The meter readings vary with the position of the float and mav be calibrated to read absolute pressure. In another form the coil d is balanced mechanically and follows the movements of the float c the movement of the coils being transmitted to a pointer. In a form employing a diaphragm, Fig. 3, a bell-like vessel g of non-magnetic material is provided with a closed arm a containing a magnetic element c connected by a rod j to a bellows h the inside of which is connected to the vacuum to be measured. The vessel g, arm a outside the bellows is exhausted. The part d is surrounded by an inductance coil d as before. In a further form the arm a communicates with the interior of the bellows which is exhausted, while the vessel g communicates with the vacuum to be measured.