Abstract: An apparatus for regulating a parameter by admission of an additive into a medium comprises a control pulse generator which is dependent on the extent of deviation from the norm, and a regulating element which effects the admission of additive during the interval of generation of a control signal. The control signal generator comprises a first timing pulse generator with a constant frequency and a first counter which receives the first timing pulses from the first timing pulse generator and transmits a first counter overflow signal after receiving a predetermined number of first timing pulses. The control signal generator further comprises a second timing pulse generator whose frequency increases with decreasing deviation form the norm and which transmits second timing pulses to a second counter which transmits a second counter overflow signal after receiving a predetermined number of second timing pulses.

Abstract: The invention relates to an adjustable stroke piston machine assembly wherein the stroke is adjustable steplessly from zero to full displacement. Two connecting rods are provided and a pivotal joint between the rods is guided by an arc shape path of a guide member. The guide member is pivotally adjustable to vary the position of the arc shaped path relative to the piston and thereby vary the stroke of the piston.

Abstract: The invention relates to apparatus for regulating the pH value, or other similar values, of a solution. The apparatus includes an actual value transmitter, a desired value transmitter, a regulator controlled by the two transmitters, and a servo unit controlled by the regulator for adding a measured amount of additive to the solution. The servo unit includes a pulse driven metering pump to provide the supply of additive. The applied pulse frequency has a logarithmic relationship to the control signal derived from an error signal which makes possible exact regulation corresponding to the logarithmetic relationship between the pH value and the concentration of additive introduced into the solution.

Abstract: Apparatus for pumping the eluent liquid through a chromatograph column is provided in the form of an electromagnetic metering pump, the outlet of which is provided with a pulsation damping device in the form of a sealed chamber having a resiliently loaded elastic wall. Considerable control of operation is obtainable by adjustment of the resilient loading and the operation of the pump (speed and stroke length). The chamber may be fitted with a pressure gauge having a closable outlet to atmosphere for purging purposes. Effective chromatographic separation of mixtures is obtainable at low equipment costs.

Abstract: The invention relates to a metering pump assembly having a reciprocable pump element with an adjustable stroke. The pump assembly includes a hydraulic system with two adjustable volume chambers, one chamber being associated with the pump element and the other with a displaceable element having an electromagnetic drive. Adjustable throttle means are provided between the two chambers for adjusting the stroke of the pump element in accordance with the setting of the throttle means.