Varian Associates, Inc.

Other

Kenneth C Judah

Detlef R Boehme

Miner N Munk

Pierre Y Achener

Stephen J Luchetti

A damper for use with a high pressure pumping system, such as a liquid chromatography system, which incorporates a reciprocating pump. The device is a generally enclosed canister including an internally formed flow volume. Inlet and outlet passages through the canister communicate with the flow volume, the inlet passage being connectable to receive the high pressure flow. A compressible body, e.g. of Teflon is positioned in the flow volume. The dimensions of the body are slightly smaller than those of the surrounding volume, whereby the high pressure flow passing between the inlet and outlet flows through the space between the body and the internal canister walls. The compression and decompression of the body in response to the pulsations in the flow dissipate the energy carried by the pulses, thereby damping same.

Damper for high pressure pumping system

A high pressure liquid chromatography system including a reservoir for a liquid mobile phase, an LC column and detector, a high pressure reciprocating pump for enabling flow from said reservoir through the column, and a positively actuated inlet valve for controlling flow from the reservoir to the pump chamber. The pump is driven by motor means, such as a stepping motor, directly coupled thereto; and the inlet valve is actuated by the power train of the motor and pump, e.g., by an eccentric carried by the pump crank shaft. The pump piston is similarly driven by an eccentric, the pump and inlet valve eccentrics being angularly displaced in their respective positions at the crank shaft, as to delay opening of the inlet valve for a predetermined period following a pump stroke, so as to enable decompression of the liquid in the pump chamber.

High pressure liquid chromatography system

A liquid chromatography system, including a reservoir for a liquid mobile phase, a liquid chromatography column, reciprocating pumping means for pumping the mobile phase through the column, and motor means for driving the pumping means through successive reciprocation cycles. Means are provided for controlling the rotational speed of the motor throughout the reciprocation cycle of the pump, so as to provide preselected average rotational speeds over predetermined subintervals of each successive reciprocation cycle. Application of the control cycle is synchronized with the pump cycle so that the said speed control is properly applied over each successive reciprocation cycle.

High performance liquid chromatography system

A liquid chromatography system including a liquid chromatography column, first and second reservoirs for solvents to be utilized as the mobile phase, reciprocating pumping means for flowing the solvents through the column, and motor means for driving the pump through successive pumping cycles including pump and fill subcycles. First and second solenoid-actuated proportioning valves are positioned at the low pressure side of the pump, i.e. between the first and second reservoirs and the pump inlet. Gradient setting means are provided for setting a preselected solvent proportion to be used over a time period. Means responsive to the gradient setting opens one of the said proportioning valves during a predetermined portion of the fill subcycle. The valves are actuated in complementary fashion with respect to opening and closing; hence the fill subcycle is divided between flow proceeding from the first and second valves in accordance with the gradient setting.

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Napa, CA, United States of America

Kenneth C Judah