Abstract: A valve arrangement for reducing the migration of one or more viruses through a filter when feed flow to the filter is resumed after a reduction in the feed flow. The valve arrangement includes an inlet line having an inlet port to be connected to a supply of product and an outlet port to be connected to an inlet of the filter, a pump, an outlet line, and a recirculation system. The recirculation system includes a recirculation line connecting the outlet line and the inlet line, and a check valve disposed along the recirculation line. When the check valve detects the feed flow reduction, a recirculation loop is created such that product is continuously recirculated through the filter during the reduction, thereby ensuring continuous fluid flow through the filter even during the reduction.

Abstract: A valve arrangement for reducing the migration of one or more viruses through a filter when feed flow to the filter is resumed after a reduction in the feed flow. The valve arrangement includes an inlet line having an inlet port to be connected to a supply of product and an outlet port to be connected to an inlet of the filter, a pump, an outlet line, and a recirculation system. The recirculation system includes a recirculation line connecting the outlet line and the inlet line, and a check valve disposed along the recirculation line. When the check valve detects the feed flow reduction, a recirculation loop is created such that product is continuously recirculated through the filter during the reduction, thereby ensuring continuous fluid flow through the filter even during the reduction.

Abstract: Chromatography and synthesis columns, assemblies, components, and methods of assembly and disassembly are disclosed including a support assembly having lifting mechanisms in each of the legs to raise and lower a frame secured to the column, a swing arm and/or carriage guiding movement of a bottom plate of the column, a bolt-free coupling between the main tube and bottom plate of the column, and upper and lower slurry ports in the main tube of the column.

Abstract: An adjustable chair is disclosed which can be used in aircraft, motor homes, or the like. In an embodiment, the chair includes a seat mounted on a base such that the weight of the seat rests on roller ball assemblies disposed on a top surface of the base. The roller ball assemblies advantageously reduce friction between the seat and the base and improve translational and rotational adjustment of the seat.

Abstract: Gas generating apparatus in which a supply of carrier gas is mixed with an impurity gas that permeates through the membrane of an impurity gas generator. A dopant gas is supplied to the impurity gas generator through a pressure controller which operates in response to a pressure monitor that monitors the pressure of the dopant gas supplied to the impurity gas generator. As the monitored pressure of the supplied dopant gas changes, the pressure of that supplied gas likewise changes in a manner which maintains a substantially constant flow rate of the impurity gas through the membrane to be mixed with a carrier gas.

Abstract: An apparatus and method are provided for preparing low concentration gas phase calibration standards. The flows of a standard mixture of impurity in a gas and a dilution gas are controlled by regulating the pressure upstream of respective calibrated orifices. The pressures of the gas flows are regulated such that a critical flow condition is maintained through the orifices. The two flows are then combined to obtain a known dilution of the impurity in the gas.

Abstract: A counterflow valve for switching between flowing gas streams without undesirable interaction of the gas with any dead volume area or non-metallic surfaces or both, which valve contains a four-way double ported ball valve having a first and second input and a first and second output, first and second inlet duct, a back pressure regulator, adjustable flow control orifice and a valve outlet duct.

Abstract: A device adapted to generate a gas flow containing a precise amount of impurities. The device comprises a membrane through which an impurity gas peremeates and mixing means to make a mixture of said impurity gas and a vector gas sweeping said membrane. The pressure of said mixture is substantially constant, but adjustable, to enhance the accuracy of the device.