Abstract: A gas ballast system for a multi-stage positive displacement pump in which a first stage includes at least one positive displacement pump stage, is equipped with an inlet valve and an outlet valve, and is connected with the following stage by an intermediate vacuum chamber, with the gas ballast system including a first conduit for supplying gas into the intermediate vacuum chamber, and a second conduit for supplying gas from the intermediate vacuum chamber into a pump chamber of the first stage or to a suction region of the first stage.

Abstract: The invention describes a system of magnetic bearings for high speed rotary vacuum pumps, having two radially centering passive magnetic bearings, which originate axially destabilizing forces and thus an unstable point. The axial position is regulated by an electrical solenoid and the operational point of the radial bearing is axially shifted with reference to the unstable point in direction of a high vacuum flange. One of two emergency bearings is located on a high vacuum end and the other is arranged on a fore-vacuum end between the solenoid and the lower passive radial bearing, the rotor, solenoid and position sensor being arranged so as to insure an easy adjustability of the rotor.

Abstract: Apparatus for heating and drying articles including an evacuable drying chamber for heating therein articles by condensation heat of the vapor of a first liquid supplied to the drying chamber, a vacuum pump for evacuating the boiler, a first vapor condenser and a second vapor condenser connected betwen the drying chamber and the vacuum pump, a thin film evaporator for receiving condensate from the drying chamber in the form of the first liquid and a second liquid having a higher boiling point than the first liquid, the second liquid being obtained from the articles within the drying chamber, a condensate collecting container for receiving from the evaporator liquid condensate which is not evaporated in the evaporator, a pressure barrier arranged between the evaporator and the collecting container and a re-evaporator arranged between the pressure barrier and the collecting container.

Abstract: Apparatus for condensing vapors at reduced pressure including a cooled vapor condenser having a liquid level sensor therein with a vacuum pump being connected by way of a control valve for drawing vapor from the vapor chamber of the condenser. The liquid level sensor opens and closes the control valve to control drawing of vapor from the vapor chamber in accordance with the level of liquid in the condenser.

Abstract: In measuring the rate of leak from a test object, a conduit system including branch lines interconnects the test object with a measuring tank, a pressure gauge, a vacuum pump and a device for removing vapor from the measuring tank. Valves in the conduit system permit the various parts to be selectively interconnected or separated. By measuring the pressure in the measuring tank under various conditions it is possible to determine the rate of leak.

Abstract: A hydraulic control arrangement with a feedback device for positioning an implement comprises a positioner including a fluid operated cylinder and piston unit, the piston of which is connected by a plurality of linkage elements to the implement. A first pump delivers through a pressure line fluid under pressure into the cylinder. A two-port three-position valve is interposed in the pressure line movable from a neutral position in which the fluid fed by the first pump is directed to a reservoir, to two operating positions to opposite sides of the neutral position, and in which one of the operating positions fluid fed by the first pump passes into the cylinder and in the other of the operating positions fluid from the cylinder can flow to the reservoir. A pair of pilot chambers are arranged at opposite ends of the valve for moving the latter from the neutral to either of the working positions. A second pump provides fluid under pressure for operating the valve.