Varian Associates, Inc.

Pierre Y Achener

Detlef R Boehme

Kenneth C Judah

Miner N Munk

A pulse damper for use in high-pressure liquid pumping applications, such as liquid chromatography, comprises a stainless steel cylindrical housing structure having threaded end caps to which inlet and outlet fittings are attached for coupling to a high-pressure liquid flow line. A spool made of a plastic material such as polytetrafluoroethylene or a perfluoroelastomer is fitted tightly within the housing structure, so that flow line liquid passes through the damper via the axial bore of the spool. The outer portion of the spool is configured to provide a cavity between the spool and the surrounding housing structure, and a compressible liquid fills this cavity. In operation, when a pressure pulse occurs in the flow line liquid, the relatively thin cylindrical wall of the spool expands radially outward in response, thereby causing a compression of the liquid in the surrounding cavity. Thus, the liquid in the cavity surrounding the spool serves as an energy-storing means for damping pulsations in the flow line.

Pulse damper for high-pressure liquid chromatography

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.

Growing community of inventors

Walnut Creek, CA, United States of America

Pierre Y Achener