Spectra-physics Gmbh

Les A Miller

Chih-Hua Chung

Vance J Nau

Ronald E Honganen

Roberta Shafer

Shahin Tabanfar

There is disclosed a maintenance reminder system for a pump. The system of the invention is coupled to the pump or the control system for the pump and determines the volume of fluid pumped by the pump. In the preferred embodiment, a piston pump is used and piston strokes are counted and converted to total volume of liquid pumped. The computer of the system maintains a database for each maintenance item containing the threshold value for each item and the total volume pumped since the last maintenance. When the total volume exceeds the threshold, a maintenance reminder is displayed and the user may display information from the database as to which item needs service. The computer updates the appropriate fields of the database after the service is performed.

Maintenance reminder system for a pump

There is disclosed herein a system for testing the flow stability of the pumping system for liquid chromatography. The system determines the flow rate and determines the number of revolutions over which the flow rate is to be measured from the flow rate. The system then measures the value of a signal which is related to the flow rate multiple times for each revolution. The maximum value and the minimum value for each revolution is recorded. After the data from the requisite number of revolutions is collected, a calculation is performed which determines the flow stability indicator which is displayed. The calculation takes a multiple of the difference between the maximum of maximums and the minimum of minimums and divides it by the sum of the maximum of maximums and the minimum of minimums.

Flow stability reporting system for a liquid chromatography system

There is disclosed herein a pump check valve test system embodied in a pump control system which control pump speed based upon actual pressure and upon actual pump speed and desired flow rate. The check valve test system disables the portion of the control system which controls pump speed based upon desired flow rate during the test. The test is comprised of timing the time it takes the pump to rotate through the portion of each cycle wherein the check valve is supposed to close and comparing this time to a known value.

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San Jose, CA, United States of America

Les A Miller