Abstract: The present disclosure relates to methodologies, systems and apparatus for cooling pump heads and providing balanced cooling and heat transfer between multiple pump heads. Multi-pump systems that are used to pump fluids that vary greatly in density with minor changes in temperature, such as the mobile phase of a C02-based chromatography system, require highly stable temperature conditions. In order to achieve a substantially equal average heat transfer between multiple pump heads and a coolant fluid, coolant fluid may be flowed through coolant passageways within the pump heads in a recursive and/or parallel coolant flow patterns. Such recursive and/or parallel coolant fluid flow patterns provide increased stability in temperature, compressibility, and density of the fluids passing through a multi-pump system.

Abstract: The present disclosure relates to methodologies, systems and apparatus for cooling pump heads and providing balanced cooling and heat transfer between multiple pump heads. Multi-pump systems that are used to pump fluids that vary greatly in density with minor changes in temperature, such as the mobile phase of a CO2-based chromatography system, require highly stable temperature conditions. In order to achieve a substantially equal average heat transfer between multiple pump heads and a coolant fluid, coolant fluid may be flowed through coolant passageways within the pump heads in a recursive and/or parallel coolant flow patterns. Such recursive and/or parallel coolant fluid flow patterns provide increased stability in temperature, compressibility, and density of the fluids passing through a multi-pump system.

Abstract: The present technology relates to methodologies, systems and apparatus for separating a liquid and a gas from a multi-phase flow stream. In particular, a gas-liquid separator having a curvilinear flow path sized is described. The flow path is designed to create a shift in the axial velocity of the primary flow field through the gas-liquid separator and generate a secondary flow field effect perpendicular to the primary flow field. The curvilinear flow path can minimize additional dispersion and provide improved efficiencies in fraction collection.

Abstract: The present disclosure relates to methodologies, systems and apparatus for cooling a supersaturated or mixed-phase solution to increase the solubility of gases dissolved therein. In a fluid chromatography system, the mobile phase may include a pressurized mixture including a gas, such as CO2, and prior to fraction collection and/or detection a portion of the gas is extracted via a gas/liquid separator. Cooling the substantially liquid phase eluent exiting the gas/liquid separator increases the solubility of any remnant gas still dissolved within the eluent. The increased solubility of the remnant gas prevents out gassing, provides more consistent flow of the eluent through the system, and results in more efficient collection and analysis of a desired sample.

Abstract: Described is an apparatus for providing a fluid at an increased pressure. The apparatus has a range of applications including use with carbon dioxide-based chromatography systems to achieve accurate flow rate control for a carbon dioxide pump. The apparatus includes a thermally-controlled chamber, chamber inlet and outlet check valves, and a temperature controller to control a temperature of fluid inside the chamber. The apparatus also includes a capacitance chamber in fluidic communication with the outlet check valve. A flow of gas passes into the chamber through the inlet check valve when a fluid pressure inside the chamber is less than an inlet fluid pressure and out from the chamber through the outlet check valve when the fluid pressure inside the chamber is greater than an outlet fluid pressure. Thermal control of the chamber allows accurate control of the gas flow into and out from the chamber.

Abstract: Methods, systems and apparatus are provided for degassing a supersaturated solution. An example degasser is described having a continuous body of gas-permeable tubing to remove an amount of a gas from the supersaturated solution below the gas's saturation point in the supersaturated solution. The degasser can be connected to at least one of a fraction collector or a detector. The example degasser is sized and/or positioned to cause a change in pressure (?P) across the degasser to drive removal of a dissolved gas from a supersaturated solution passing through the degasser. As a result of the reduction of gas, efficiencies in system flow and fraction collection are achieved.

Abstract: Described is a method of generating a flow having a composition gradient. A plurality of pump strokes is generated for each pump in a plurality of pumps. Each pump stroke has an initiation time and provides a volume contribution of a liquid to be mixed in the flow according to the composition gradient for the flow. The pump strokes of the pumps are controlled so that a sum of the volume contributions of the liquids that occurs between consecutive initiations of one of the pumps is maintained at a constant value throughout the duration of the flow. For each pump, the flow rates and the times between stroke initiations can change as long as the sum of all volumes contributed between the consecutive initiations of one of the pumps is held constant. Advantageously, the method achieves a constant compositional noise characteristic throughout the duration of the flow.

Abstract: The present disclosure relates to methodologies, systems and apparatus for cooling pump heads and providing balanced cooling and heat transfer between multiple pump heads. Multi-pump systems that are used to pump fluids that vary greatly in density with minor changes in temperature, such as the mobile phase of a C02-based chromatography system, require highly stable temperature conditions. In order to achieve a substantially equal average heat transfer between multiple pump heads and a coolant fluid, coolant fluid may be flowed through coolant passageways within the pump heads in a recursive and/or parallel coolant flow patterns. Such recursive and/or parallel coolant fluid flow patterns provide increased stability in temperature, compressibility, and density of the fluids passing through a multi-pump system.

Abstract: Described is a method of generating a flow having a composition gradient such as a mobile phase gradient for liquid chromatography. A pair of pumps is operated such that the initiations of pump strokes for one pump are controlled to occur between the initiations of pump strokes for the other pump so that the sequences of pump strokes fort the two pumps are interspersed in time. Initiations of the pump strokes of the second pump are offset in time relative to initiations of the pump strokes of the first pump such that variations in the flow rates of the first and second pumps due to initiation do not overlap in time. The volume of liquid contributed by a pump stroke is controlled according to the relative contribution of the respective pump to the composition gradient.

Abstract: The present disclosure relates to methodologies, systems and apparatus for cooling a supersaturated or mixed-phase solution to increase the solubility of gases dissolved therein. In a fluid chromatography system, the mobile phase may include a pressurized mixture including a gas, such as CO2, and prior to fraction collection and/or detection a portion of the gas is extracted via a gas/liquid separator. Cooling the substantially liquid phase eluent exiting the gas/liquid separator increases the solubility of any remnant gas still dissolved within the eluent. The increased solubility of the remnant gas prevents out gassing, provides more consistent flow of the eluent through the system, and results in more efficient collection and analysis of a desired sample.

Abstract: Described is a method for vacuum degassing of a liquid such as a solvent for a liquid chromatography system. The method includes modulating application of a vacuum to a fluid channel of a degasser so that each volume of a liquid drawn from the degasser experiences a residence time that is equal to the residence times of the other volumes. The residence time is determined as a time that the volume resides in the fluid channel under application of the vacuum and to a magnitude of the applied vacuum. The method is advantageous for use with liquid chromatography systems where differences in the diffusion rates of solvents into the degasser vacuum can otherwise introduce error into the composition gradient of a mobile phase.

Abstract: Described is a method for purging a fluid channel is a low pressure gradient formation liquid flow system. Control of the fluid channels for multiple solvents allows for one or more static volumes of solvents not intended for use in an isocratic flow to be purged from their fluid channels to avoid contamination of the isocratic solvent. Advantageously, the method avoids the need to modify equipment or to reconfigure a pumping system so that the inlet is directly coupled to a single solvent source. Thus there is no need to bypass existing valves and liquid coupling components where solvents are combined during conventional gradient operation.

Abstract: Methods, systems and apparatus are provided for degassing a supersaturated solution. An example degasser is described having a continuous body of gas-permeable tubing to remove an amount of a gas from the supersaturated solution below the gas's saturation point in the supersaturated solution. The degasser can be connected to at least one of a fraction collector or a detector. The example degasser is sized and/or positioned to cause a change in pressure (?P) across the degasser to drive removal of a dissolved gas from a supersaturated solution passing through the degasser. As a result of the reduction of gas, efficiencies in system flow and fraction collection are achieved.

Abstract: The present technology relates to methodologies, systems and apparatus for separating a liquid and a gas from a multi-phase flow stream. In particular, a gas-liquid separator having a curvilinear flow path sized is described. The flow path is designed to create a shift in the axial velocity of the primary flow field through the gas-liquid separator and generate a secondary flow field effect perpendicular to the primary flow field. The curvilinear flow path can minimize additional dispersion and provide improved efficiencies in fraction collection.

Abstract: Described is a method for purging a fluid channel is a low pressure gradient formation liquid flow system. Control of the fluid channels for multiple solvents allows for one or more static volumes of solvents not intended for use in an isocratic flow to be purged from their fluid channels to avoid contamination of the isocratic solvent. Advantageously, the method avoids the need to modify equipment or to reconfigure a pumping system so that the inlet is directly coupled to a single solvent source. Thus there is no need to bypass existing valves and liquid coupling components where solvents are combined during conventional gradient operation.

Abstract: Described is a method for vacuum degassing of a liquid such as a solvent for a liquid chromatography system. The method includes modulating application of a vacuum to a fluid channel of a degasser so that each volume of a liquid drawn from the degasser experiences a residence time that is equal to the residence times of the other volumes. The residence time is determined as a time that the volume resides in the fluid channel under application of the vacuum and to a magnitude of the applied vacuum. The method is advantageous for use with liquid chromatography systems where differences in the diffusion rates of solvents into the degasser vacuum can otherwise introduce error into the composition gradient of a mobile phase.

Abstract: Described is a method of generating a flow having a composition gradient. A plurality of pump strokes is generated for each pump in a plurality of pumps. Each pump stroke has an initiation time and provides a volume contribution of a liquid to be mixed in the flow according to the composition gradient for the flow. The pump strokes of the pumps are controlled so that a sum of the volume contributions of the liquids that occurs between consecutive initiations of one of the pumps is maintained at a constant value throughout the duration of the flow. For each pump, the flow rates and the times between stroke initiations can change as long as the sum of all volumes contributed between the consecutive initiations of one of the pumps is held constant. Advantageously, the method achieves a constant compositional noise characteristic throughout the duration of the flow.

Abstract: Described is a method of generating a flow having a composition gradient such as a mobile phase gradient for liquid chromatography. A pair of pumps is operated such that the initiations of pump strokes for one pump are controlled to occur between the initiations of pump strokes for the other pump so that the sequences of pump strokes fort the two pumps are interspersed in time. Initiations of the pump strokes of the second pump are offset in time relative to initiations of the pump strokes of the first pump such that variations in the flow rates of the first and second pumps due to initiation do not overlap in time. The volume of liquid contributed by a pump stroke is controlled according to the relative contribution of the respective pump to the composition gradient.

Abstract: A fitting for coupling fluidic paths, such as high pressure fluidic paths in liquid chromatography systems, includes a compression nut, a tube assembly and a compression member. The compression nut has a threaded outer surface to engage a threaded bore of a receiving port and the tube assembly has an outer surface and an end face to contact a sealing surface of the receiving port. The compression member is pre-staked to the outer surface of the tube assembly at a predetermined distance from the end face and has a tapered surface to engage a surface of the receiving port. The predetermined distance permits the tube assembly to be inserted into the receiving port so that the end face makes contact with the sealing surface without the tapered surface engaging a surface of the receiving port and so that the threaded outer surface of the compression nut engages the threaded bore.