Steven J. Ciavarini - Bellingham MA Robert J. Dumas - Upton MA
Assignee:
Waters Investments Limited
International Classification:
B01D 1508
US Classification:
417216, 210101
Abstract:
A serial, dual piston high pressure fluid pumping system that overcomes the difficulties of gas in the fluid stream without the need for added mechanical valves or fluid paths. A bubble detection and recovery mechanism monitors compression and decompression volumes of the serially configured dual pump head pump, and the overall system delivery pressure. Bubble detection is effected by sensing a ratio of compression to decompression volume and determining if the ratio exceeds an empirical threshold that suggests the ratio of gas-to-liquid content of eluent or fluid in the system is beyond the pumps ability to accurately meter a solvent mixture. The magnitude of the ratio of compression to decompression volume indicates that either the intake stroke has a bubble or that the eluent has a higher-than-normal gas content. Once a bubble has been detected, recovery is effected by forcing the pump into a very high stroke volume with the compression and decompression stroke limits constrained to obtain the largest delivery stroke compression ratio that will expel a bubble or solvent that has detrimental quantities of gas.
Bubble Detection And Recovery In A Liquid Pumping System
Steven J. Ciavarini - Bellingham MA Robert J. Dumas - Upton MA
Assignee:
Waters Investments Limited
International Classification:
F04B 1924
US Classification:
417 53, 417216
Abstract:
A serial, dual piston high pressure fluid pumping system that overcomes the difficulties of gas in the fluid stream without the need for added mechanical valves or fluid paths. A bubble detection and recovery mechanism monitors compression and decompression volumes of the serially configured dual pump head pump, and the overall system delivery pressure. Bubble detection is effected by sensing a ratio of compression to decompression volume and determining if the ratio exceeds an empirical threshold that suggests the ratio of gas-to-liquid content of eluent or fluid in the system is beyond the pumps ability to accurately meter a solvent mixture. The magnitude of the ratio of compression to decompression volume indicates that either the intake stroke has a bubble or that the eluent has a higher-than-normal, gas content. Once a bubble has been detected, recovery is effected by forcing the pump into a very high stroke volume to achieve a high compression ratio to expel a bubble, and automatically apportioning an optimal amount of piston travel necessary to keep gases compressed into the solution and maintain steady flow.
Methods And Apparatus For Determining The Presence Or Absence Of A Fluid Leak
Joseph A. Luongo - Walpole MA, US Steven J. Ciavarini - Natick MA, US Robert Q. Tacconi - Medfield MA, US Frank A. Rubino - North Attleboro MA, US Robert J. Dumas - Upton MA, US
Assignee:
Waters Investments Limited - DE
International Classification:
F04B 49/00 G01M 3/04 G08B 21/00
US Classification:
417 53, 417 63, 73 40, 340605
Abstract:
Embodiments of the present invention feature a method and apparatus for detecting defects, such as, leaks, component failure and adverse performance. One embodiment of the present apparatus for pumping fluid comprises a pumping chamber having an inlet and an outlet powered by a motor. The motor operates in pumping mode upon receiving a pumping signal. The apparatus further comprises at least one inlet valve in fluid communication with the inlet of the pumping chamber. And, the apparatus comprises a switchable valve in fluid communication with the outlet of the pumping chamber. The switchable valve has a closed position and an open position, and assumes the closed position upon receiving a close signal. A pressure measuring device is in fluid communication with the pumping chamber, between said inlet valve and switchable valve. The pressure measuring device determines a minimal pressure and first threshold pressure at a first time and a second threshold pressure at a second time.
Devices, Systems And Methods For Flow-Compensating Pump-Injector Synchronization
Systems, devices, and methods to mitigate the pressure disturbance associated with the injection of low-pressure analyte samples into a high-pressure HPLC fluid stream to enhance chromatographic performance related to retention time and reproducibility. The injection event is coordinated with active pressure control of a binary solvent delivery system to virtually eliminate the customary pressure drop when the low-pressure loop is brought on line. Consistent timing with the injection event of the mechanical position of the delivery pump pistons, and the start and subsequent gradient delivery generates reproducible results.
Devices, Systems And Methods For Flow-Compensating Pump-Injector Synchronization
Systems, devices, and methods to mitigate the pressure disturbance associated with the injection of low-pressure analyte samples into a high-pressure HPLC fluid stream, to enhance chromatographic performance related to retention time and reproducibility. The preferred embodiment coordinates the injection run with active pressure control of a binary solvent delivery system to virtually eliminate the customary pressure drop when the low-pressure loop is brought on line. An additional benefit that enhances reproducibility is accomplished by forcing a consistent timing relationship between the injection run, the mechanical position of the delivery pump pistons, and the start and subsequent gradient delivery.
Valve Switch Modulation For Reducing Errors Due Oscillations Of The Inlet Fluid Of A Pump System
Joshua A. Shreve - Franklin MA, US Steven J. Ciavarini - Natick MA, US
Assignee:
Waters Technologies Corporation - Milford MA
International Classification:
B01F 15/04 B01F 13/00
US Classification:
3661621, 366348, 366349
Abstract:
Described is a method of reducing liquid composition errors in a low-pressure mixing pump system. Packets representing the switching intervals of each component of the desired fluid mixture are provided to an intake of the mixing pump system. For each packet, a switching time associated with at least one of the components in the packet is modulated. Modulated switching times are based on time offsets that are specifically selected according to the undesirable frequency characteristic of an intake response of the mixing pump system. The average of the volumes contributed by the packets thus modulated is equal to a component volume that achieves a desired proportion of the component in the output flow of the mixing pump system. Modulated switching times enable the reduction or elimination of composition error in the output flow of the mixing pump system.
Valve Switch Modulation For Reducing Errors Due To Oscillations Of The Inlet Fluid Of A Pump System
Described is a method of reducing liquid composition errors in a low-pressure mixing pump system. Packets representing the switching intervals of each component of the desired fluid mixture are provided to an intake of the mixing pump system. For each packet, a switching time associated with at least one of the components in the packet is modulated. Modulated switching times are based on time offsets that are specifically selected according to the undesirable frequency characteristic of an intake response of the mixing pump system. The average of the volumes contributed by the packets thus modulated is equal to a component volume that achieves a desired proportion of the component in the output flow of the mixing pump system. Modulated switching times enable the reduction or elimination of composition error in the output flow of the mixing pump system.
Solvent Delivery System For Liquid Chromatography That Maintains Fluid Integrity And Pre-Forms Gradients
Steven J. Ciavarini - Natick MA, US Jeffrey W. Finch - Gig Harbor WA, US Keith Fadgen - Hope Valley RI, US Hongji Liu - Grafton MA, US
Assignee:
WATERS INVESTMENTS LIMITED - New Castle DE
International Classification:
G01N 30/02
US Classification:
73 6156
Abstract:
A solvent delivery subsystem for a chromatography device performs relatively low pressure, high flow mixing of solvents to form a gradient and subsequent high pressure, low flow delivery of the gradient to the separation column. The mixing of the gradient is independent and does not interfere with the gradient delivery. To form the gradient, the outputs of an aqueous pump and an organic pump are mixed to fill a storage capillary while a downstream point from the storage capillary is vented to atmosphere. After gradient formation, the vent to atmosphere is closed, the solvent delivery system rises to high pressure, and only the aqueous pump runs for gradient delivery. To maintain integrity of the fluid stream, the solvent delivery system uses feed forward compensation and controls at least one parameter selected from the group consisting of pressure and flow in the conduit means to follow a gradual ramp.