GB315325A - Improvements in or relating to vacuum gauges - Google Patents

Abstract

315,325. General Electric Co., Ltd., (Assignees of CeskomoraoskÓ Kolben-Danek Akciova Spolecnost, Farbinger, F., and Cacheux, R.). July 11, 1928, [Convention date]. Liquid-level pressure gauges.-Comprises a mercury type vacuum gauge used for automatically starting and stopping a vacuum pump wherein the height of the mercury level is controlled by rotating the gauge around the axis of the inlet pipe therefor. The gauge comprises a glass tube s of annular form which is connected to the vacuum valve o by a part of the gauge which is at rightangles to the annular part. The groove d in the valve body establishes communication between the gauge and the vacuum tank. For adjusting the pressures at which the mercury in the gauge engages the contacts a, b the valve need be turned just a small amount. It is closed by rotating it through 90‹. The three contacts a, b, c are fused into the glass and serve for starting, stopping and supplying current to the motor driving the pump. When the vacuum is low, the mercury fills the tube s and the contacts a and b are connected with the contact c. The relay A is thus energized and the contacts k<1>, k<2> close, the contact k<1> completing the circuit for the contactor B and the pump starts. As the vacuum increases the mercury falls, and when the contact b is passed the pump stops. The meroury level has to reach the contact a before the relay A is energized to restart the pump. In the case of failure of the gauge, the latter is rotated until the stationary contacts come to position 4 when the motor is started by operating the hand switch v. By moving the gauge to the position 5, the contacts are disconnected and the gauge may be dismantled. The contacts m<1>, n' and p<1> are carried by the rotating part of the gauge. Normally the two upper pairs of stationary contacts engage the movable contacts m<1>, n<1> between positions 1 and 3.