Abstract: A centrifugal blood processing apparatus comprising a centrifuge rotor, a separation chamber, a tubing set for conducting blood components and fluids and having an inlet line, an outlet line and a storage solution line in fluid communication with the outlet line at a junction. The apparatus controls pumps to conduct a predetermined quantity of storage solution to a collected blood component. The apparatus also purges blood components in the tubing set by applying a negative pressure and positive pressure. A disposable blood processing set has a separation chamber; a tubing set including an inlet line in fluid and an outlet and a storage solution line connected to the outlet line at a junction.

Abstract: A separation apparatus and method are employed using a separation channel for rotation about an axis. Such channel includes radially spaced apart inner and outer side wall portions and an end wall portion. An inlet conveys fluid into the channel. A barrier is located in the channel intermediate of the inner and outer side wall portions. A first flow path communicates between upstream and downstream sides of the barrier. A collection region may be located downstream of the barrier for communication with the first flow path. An outer side wall section of the channel may be positioned radially outward of an upstream section thereof. The barrier may join the outer side wall portion along a substantial portion of an axial length of the channel. First and second exit flow paths may allow communication with the channel either upstream or downstream of the barrier or both.

Abstract: A cell separation set for separating blood components, having a cell separation chamber with a first entry section having a wall with an outwardly flared curve, the entry section having an axial length and an inmost maximum diameter perpendicular to the axial length, the axial length being greater than the inmost maximum diameter. The cell separation chamber further comprises a separation section having a wall comprising an inward curve. A transition section between the entry section and the separation section has a wall comprising a second inward curve, the second inward curve being different from said first inward curve. The first curve may be tangent to the second curve at a first junction between the first and second curves and the second curve may be tangent to the third curve at a second junction between the second and third curves.

Abstract: A collection device that captures liquid sample that may spill or leak during the process of loading or unloading liquid sample while a centrifuge rotor is spinning. Such capture prevents the leaked liquid sample from coming into contact with sensitive components inside the centrifuge chamber, thereby protecting the centrifuge from damage.

Abstract: A platelet collection device comprising a centrifugal spin-separator container with a cavity having a longitudinal inner surface. A float in the cavity has a base, a platelet collection surface above the base, an outer surface. The float density is below the density of erythrocytes and above the density of plasma. The platelet collection surface has a position on the float which places it below the level of platelets when the float is suspended in separated blood. During centrifugation, a layer of platelets or buffy coat collects closely adjacent the platelet collection surface. Movement of a float having a density greater than whole blood through the sedimenting erythrocytes releases entrapped platelets, increasing the platelet yield.

Abstract: A centrifugal processing bag, system and method for separating the components of a mixed material is presented. The processing bag includes a hub and a first port for receiving the mixed material, where the first port includes an outlet positioned within the processing bag at a perimeter of the bag. The processing bag also including a second port having a second port inlet spaced proximate the hub and away from a central axis of the hub. The second port directs a separated material collected from the second port inlet out of the processing bag.

Abstract: An apparatus for separating blood into blood components using a separation vessel satellite bags mounted on a centrifuge rotor and a balancing assembly for the centrifuge to compensate for changes to the center of gravity.

Abstract: A blood separation chamber is provided for separating blood into its constituent parts by rotation about an axis. The chamber has a central hub coinciding with the axis and spaced apart high-G and low-G walls which define therebetween a separation channel. The chamber further includes a plurality of parallel radial walls extending outwardly from the central hub and defining a radial fluid flow passage between each adjacent pair of walls. Each fluid flow passage communicates between the central hub and the separation channel. One of the radial walls includes a radially outer end portion defining a barrier in the separation channel intermediate the low-G and high-G walls and having generally parallel upstream and downstream sides. The separation channel has a recessed portion located radially outward of the high-G wall and extending between the upstream and downstream sides of the barrier.

Abstract: A flexible processing and/or expressor chamber for a biological cell processing apparatus is provided which may include a first side and a second side and having a expandable wall, wherein a first end of the expandable wall is attached to a circumference of the first side of the flexible chamber and a second end of the expandable wall is attached to a circumference of the second side of the flexible chamber. Either or both sides of the chamber may include an axial opening.

Abstract: A hermetically sealed solids discharge centrifugal separator exhibits low-shear filling, acceleration, and separation of feed material. The separator can be particularly useful for separation and recovery of sensitive solids such as chemical or biological substances. The separator accommodates disposable sample contacting elements to eliminate the need for clean-in-place and sterilize-in-place operations. Some embodiments of the separator feature dual solids discharge pistons, which fully optimize recovery of valuable solids.

Abstract: Baglike container (1) that is fitted in a centrifuge to thereby allow centrifugation of any dispersion liquid placed therein. The baglike container for centrifugation is one comprising a main frame constituted of first container wall (3) with recess portion (6) formed so as to allow fitting in a centrifuge and with flange portion (7) provided on an open face border of the recess portion (6) and constituted of flexible second container wall (4) having its peripheral portion sealed mutually with the flange portion (7) of the first container wall (3) so as to define storing space (6?) for dispersion liquid in cooperation with the recess portion (6) and further comprising port (5) fitted to the main frame in a fashion allowing communication with the storing space (6?), wherein the recess portion (6) defining the storing space (6?) can be set in the centrifuge so that centrifugal force perpendicular to the bottom plane of the recess portion (6) applies.

Abstract: A method used in connection with processing of blood components, wherein blood products are then filtered via a filter rotating along with a centrifuge rotor and the sensed pressure may be used in connection with controlling the pumping of the blood products and/or in connection with determining the location of an interface associated with the blood products.

Abstract: The invention provides a method, apparatus and system for separating blood and other types of cellular components, and can be combined with holographic optical trapping manipulation or other forms of optical tweezing. One of the exemplary methods includes providing a first flow having a plurality of blood components; providing a second flow; contacting the first flow with the second flow to provide a first separation region; and differentially sedimenting a first blood cellular component of the plurality of blood components into the second flow while concurrently maintaining a second blood cellular component of the plurality of blood components in the first flow. The second flow having the first blood cellular component is then differentially removed from the first flow having the second blood cellular component. Holographic optical traps may also be utilized in conjunction with the various flows to move selected components from one flow to another, as part of or in addition to a separation stage.

Abstract: Embodiments of a centrifuge comprise a housing, a rotatable shaft extending upwardly into the housing and comprising a rare earth metal magnet disposed adjacent an upper surface of the rotatable shaft and a centrifuge basket configured to rotate with the rotatable shaft and magnetically coupled to the rare earth metal magnet of the rotatable shaft.

Abstract: A flexible processing and/or expressor chamber for a biological cell processing apparatus is provided which may include a first side and a second side and having a expandable wall, wherein a first end of the expandable wall is attached to a circumference of the first side of the flexible chamber and a second end of the expandable wall is attached to a circumference of the second side of the flexible chamber. Either or both sides of the chamber may include an axial opening.

Abstract: A device for loading a set of bags into the rotor of a centrifuge including a loading container having an annular rim extending outwardly such that the annular rim rests on the turn table of the rotor.

Abstract: A method for separating a volume of a composite liquid into at least a first component and a second component is performed in a centrifuge cooperating with a separation bag containing the volume of composite liquid. The separation bag is connected to at least a first component bag and a second component bag. The separation bag is spun so as to centrifuge the volume of composite liquid and cause the sedimentation of the at least first and second components. When the at least first and second components have sedimented, the first component is transferred at least one first transfer flow rate into the first component bag. When the first component has been transferred into the first component bag, the second component is transferred into the intermediate component bag at least one second transfer flow rate that is different from the at least one first transfer flow rate.

Abstract: An apparatus and method are provided for separating components of a fluid or particles. A separation vessel having a barrier dam is provided to initially separate an intermediate density components of a fluid, and a fluid chamber is provided to further separate these intermediate density components by forming an elutriative field or saturated fluidized particle bed. The separation vessel includes a shield for limiting flow into the fluid chamber of relatively high density substances, such as red blood cells. The separation vessel also includes a trap dam with a smooth, gradually sloped downstream section for reducing mixing of substances. Structure is also provided for adding additional plasma to platelets and plasma flowing from the fluid chamber. The system reduces clumping of platelets by limiting contact between the platelets and walls of the separation vessel.

Abstract: A system and method are used in connection with processing of blood components. The processing of blood components may involve centrifugal separation and/or filtering of the blood components. In some examples, at least some blood components are centrifugally separated in a chamber and then filtered via a filter rotating along with a centrifuge rotor, wherein the filter is located closer than the chamber to an axis of rotation of the rotor. The filter may include a porous filtration medium configured to filter leukocytes, platelets, and/or red blood cells. Some examples include a pressure sensor sensing pressure of pumped blood components. The sensed pressure may be used in connection with controlling the pumping of the blood products and/or in connection with determining the location of an interface associated with the blood products. Other uses of the sensed pressure are also possible.

Abstract: For an effective separation of more than one kind of particle from a mixture, a plurality of separation stages are provided, arranged in series. Mixer elements may be disposed along the flow path to disturb the sedimenting particles, to release entrained lighter particles. Further, the separation channel may widen near the particle recovery port(s), to well suspend lighter particles in the fluid as denser particles are extracted and/or to allow gravitational forces to more effectively influence particle movement. In an example embodiment one stage utilizes Coriolis force in a narrow, radial passage for concentrating and agglomerating particles. The serial separation stages may be communicated with a radially inward extending passage to limit undesirable particle spill-over.

Abstract: A platelet collection device comprising a centrifugal spin-separator container with a cavity having a longitudinal inner surface. A float in the cavity has a base, a platelet collection surface above the base, an outer surface. The float density is below the density of erythrocytes and above the density of plasma. The platelet collection surface has a position on the float which places it below the level of platelets when the float is suspended in separated blood. During centrifugation, a layer of platelets or buffy coat collects closely adjacent the platelet collection surface. Platelets are then removed from the platelet collection surface. Movement of a float having a density greater than whole blood through the sedimenting erythrocytes releases entrapped platelets, increasing the platelet yield.

Abstract: The invention relates to a centrifuge including a first rotatable mechanism having a rotation axis with a fluid retentive housing being coaxially mounted on the first rotatable mechanism for co-rotation therewith; a second rotatable mechanism having a rotation axis with the first and second rotatable mechanisms being coaxially interconnected for co-rotation around a common axis; and fluid tubing connected to the axis of the fluid retentive housing and having a distal length that extends axially outwardly from the fluid retentive housing. A support arm is mounted to the second rotatable mechanism, a support tube receives therethrough at least a part of the distal length of the fluid tubing, and a bearing member rotatably supports the support tube in the support arm, whereby upon rotation of the first and second rotatable mechanisms, the fluid tubing is free to one of rotate with and rotate relative to the support tube.

Abstract: A rotor for collecting and centrifuging biological fluids in a range of volumes. The rotor includes an elastic impermeable diaphragm which defines at least a portion of a variable-volume processing chamber, where the fluid is centrifuged. The rotor includes a rigid mounting member, to which the diaphragm is mounted and which is held and spun by a chuck. Preferably, this rigid mounting member includes a boundary wall which together with the elastic diaphragm defines the chamber. The boundary wall may be a substantially imperforate circular wall which extends to the periphery of the processing chamber but defining one opening, preferably near the axis of rotation, permitting a conduit or conduits to pass therethrough so as to be in fluid communication with the processing chamber. The rotor may include a separate structure for controlling the flow of liquid out of the chamber into the conduit.

Abstract: The present invention relates to a separation device notably for a flow-force fractionation of suspended substances in a liquid carrier, said separation device comprising a separation channel and a counter-channel. The object of the present invention is mainly the separation of living cells, preferably of human origin, in particular cells which are found in body fluids.

Abstract: A method and apparatus for selectively expressing one or more selected fluid materials out of a fluid container, including a centrifuge rotor having a round centrifuge chamber of selected volume, a round expandable enclosure disposed within the centrifuge chamber having a rotation axis coincident with the central rotation axis and a flexible wall, a pump for controllably pumping a selected volume of expressor fluid into and out of the expandable enclosure wherein the fluid container is receivable with the centrifuge chamber, and a retaining mechanism for holding the fluid container within the centrifuge chamber in a coaxial position. The flexible wall of the fluid container is in contact with the flexible wall of the expandable enclosure.

Abstract: A bag loader for loading and unloading at least one satellite bag into and from the central compartment of a rotor of an apparatus for separating a composite liquid into at least two components comprises an upper part for removably securing an upper portion of at least one satellite bag; a lower part comprising a receptacle; and an intermediate part connecting the upper part to the lower part and exposing an intermediate portion of a satellite bag.

Abstract: The present invention is directed to a centrifuge rotor (10) having a rotor housing (14) with a substantially cylindrical in shape and having a substantially uniform opening extending through the center of the housing and along a length thereof, a rotor core (16) having a substantially cylindrical shape and sized and shaped to fit within the opening of the rotor housing. The rotor core further has at least two channels (30) in an outer surface thereof such that the channels, along with an interior wall of the rotor housing, define two sample spaces into which sample is delivered while the rotor is in operation.

Abstract: A system for separating a composite fluid into component parts thereof, including: a centrifuge having a rotor with a separation space and at least two valve members disposed thereon and a container set having a separation container adapted to be disposed in the separation space of the rotor and first and second collection containers connected to the separation container by a first and a second tubes. The tubes are adapted to be disposed in operative relationship with the valve members so that flow through the tubes may be controlled thereby. Three components of the composite fluid may be separated therefrom by the present system and two components may be moved to the collection containers. The container set may further include a third collection container connected to the separation container by a tube, and a third component may thus be moved to this third container.

Abstract: A centrifuge apparatus for processing blood comprising a bottom spring-loaded support plate; a top support plate; an axial inlet/outlet for blood to be processed and processed components of the blood, the axial inlet/outlet being attached to the top support plate by a rotating seal assembly; a variable volume separation chamber mounted between the bottom support plate and the top support plate, the variable volume separation chamber being fluidly connected to the axial inlet/outlet; a pump fluidly connected to the axial inlet/outlet; and a rotary drive unit attached to the bottom support plate. The top support plate is fixed vertically and the bottom spring-loaded support plate is mounted on springs that maintain pressure on the variable volume separation chamber and allow the bottom support plate to move vertically.

Abstract: The invention provides a method, apparatus and system for separating blood and other types of cellular components, and can be combined with holographic optical trapping manipulation or other forms of optical tweezing. One of the exemplary methods includes providing a first flow having a plurality of blood components; providing a second flow; contacting the first flow with the second flow to provide a first separation region; and differentially sedimenting a first blood cellular component of the plurality of blood components into the second flow while concurrently maintaining a second blood cellular component of the plurality of blood components in the first flow. The second flow having the first blood cellular component is then differentially removed from the first flow having the second blood cellular component. Holographic optical traps may also be utilized in conjunction with the various flows to move selected components from one flow to another, as part of or in addition to a separation stage.

Abstract: A flexible, disposable centrifuge bag for receiving and holding a fluid sample, comprising one or more tubes and upper and lower flexible sheets having doughnut shaped configurations. The upper and lower sheets are superimposed and completely sealed together at their outer perimeters to define an outer perimeter of the centrifuge bag. The inner perimeter of the bag defines a central core. The tubes are sandwiched between the upper and lower sheets and extend from the central core of the centrifuge bag. The upper and lower sheets are sealed together at their inner perimeters such that the tubes are sealed between said upper and lower sheets at the inner perimeter. The bag may be used to harvest platelet rich plasma from whole blood in either a batch method or while simultaneously infusing additional aliquots of whole blood into the bag during centrifugation.

Abstract: A system for separating a composite fluid into component parts thereof, including: a centrifuge having a rotor with a separation space and at least two valve members disposed thereon and a container set having a separation container adapted to be disposed in the separation space of the rotor and first and second collection containers connected to the separation container by a first and a second tubes. The tubes are adapted to be disposed in operative relationship with the valve members so that flow through the tubes may be controlled thereby. Three components of the composite fluid may be separated therefrom by the present system and two components may be moved to the collection containers. The container set may further include a third collection container connected to the separation container by a tube, and a third component may thus be moved to this third container.

Abstract: The invention relates to disposable device for the continuous centrifugal separation of a physiological fluid. The inventive device comprises: a fixed axial element; a centrifugation chamber which is mounted such that it can rotate around the axis of said element; an inlet channel for the blood to be centrifuged, the dispensing port of which is located close to the base of the chamber; and an outlet passage for a separated constituent, the inlet port of which is located close to the other end of the chamber in a concentrated area of one of the separated constituents having the lowest mass density in order for same to be removed continuously. The above-mentioned chamber takes the form of a long tube.

Abstract: A removable, spiral vane insert for receipt by a centrifuge rotor enclosure includes a unitary, molded plastic spiral vane portion including a spiral vane module and a baseplate that are all integrally joined together. The spiral vane portion further includes a tubular sleeve having a longitudinal axis corresponding to the axis of rotation for the rotor.

Abstract: The invention relates to a centrifugal separator for a physiological fluid, particularly blood. The inventive separator comprises: a fixed conduit which continuously supplies a rigid disposable centrifugation chamber with the liquid to be separated; a fixed outlet conduit having an inlet port which is located in a concentrated area of at least one of the separated constituents having the lowest mass density in order for same to be removed continuously, said conduits being solidly connected to a fixed part of the chamber; means for guiding the chamber in rotation and means for driving the chamber around the axis of rotation defined by said guide means. The invention also comprises a second fixed outlet conduit having an inlet port which is located in a concentrated area of at least one of the separated constituents having the highest mass density in order for same to be removed continuously.

Abstract: A method for separating a volume of a composite liquid into at least a first component and a second component is performed in a centrifuge cooperating with a separation bag containing the volume of composite liquid. The separation bag is connected to at least a first component bag and a second component bag. The separation bag is spun so as to centrifuge the volume of composite liquid and cause the sedimentation of the at least first and second components. When the at least first and second components have sedimented, the first component is transferred at at least one first transfer flow rate into the first component bag. When the first component has been transferred into the first component bag, the second component is transferred into the intermediate component bag at at least one second transfer flow rate that is different from the at least one first transfer flow rate.

Abstract: A separation apparatus and method are employed using a separation channel for rotation about an axis. Such channel includes radially spaced apart inner and outer side wall portions and an end wall portion. An inlet conveys fluid into the channel. A barrier is located in the channel intermediate of the inner and outer side wall portions. A first flow path communicates between upstream and downstream sides of the barrier. A collection region may be located downstream of the barrier for communication with the first flow path. An outer side wall section of the channel may be positioned radially outward of an upstream section thereof. The barrier may join the outer side wall portion along a substantial portion of an axial length of the channel. First and second exit flow paths may allow communication with the channel either upstream or downstream of the barrier or both.

Abstract: A system and method are used in connection with processing of blood components. The processing of blood components may involve centrifugal separation and/or filtering of the blood components. In some examples, at least some blood components are centrifugally separated in a chamber and then filtered via a filter rotating along with a centrifuge rotor, wherein the filter is located closer than the chamber to an axis of rotation of the rotor. The filter may include a porous filtration medium configured to filter leukocytes, platelets, and/or red blood cells. Some examples include a pressure sensor sensing pressure of pumped blood components. The sensed pressure may be used in connection with controlling the pumping of the blood products and/or in connection with determining the location of an interface associated with the blood products. Other uses of the sensed pressure are also possible.

Abstract: An apparatus and method for collecting whole blood and then separating it into components for subsequent use or storage. A self-contained bag set is used to collect the sample, which may then be placed into container adapted to fit into a centrifuge for separation of components. Each component is then sequentially extracted according to density, with a sensor present in the container to control the operation of valves directing the collection of each component. Each component may then be separated into its own storage container.

Abstract: A centrifuge for processing blood and blood components in a processing bag connected to at least one secondary bag comprises a rotor for spinning a processing bag and separating a content thereof in at least two components, and a squeezing member for exposing a processing bag to an external pressure and causing a transfer of a separated component from a processing bag into a secondary bag. Electrically powered devices, such as valves and photocells, are mounted on the rotor for controlling a transfer of fluid from a processing bag into a secondary bag. An electrical power supply system supplies the electrically powered devices with electrical power through the rotor.

Abstract: A platelet collection device comprising a centrifugal spin-separator container with a cavity having a longitudinal inner surface. A float in the cavity has a base, a platelet collection surface above the base, an outer surface. The float density is below the density of erythrocytes and above the density of plasma. The platelet collection surface has a position on the float which places it below the level of platelets when the float is suspended in separated blood. During centrifugation, a layer of platelets or buffy coat collects closely adjacent the platelet collection surface. Platelets are then removed from the platelet collection surface. Movement of a float having a density greater than whole blood through the sedimenting erythrocytes releases entrapped platelets, increasing the platelet yield.

Abstract: An adapter for use with a centrifuge. Features of the adapter allow for less friction during extraction of the adapter and separation efficiency by preventing disturbances to the separated materials. In addition, the adapter includes features that support the walls of a sample container and prevent force from damaging the sample container during a centrifuge separation procedure.

Abstract: A system for separating a composite fluid into component parts thereof, including: a centrifuge having a rotor with a separation space and at least two valve members disposed thereon and a container set having a separation container adapted to be disposed in the separation space of the rotor and first and second collection containers connected to the separation container by a first and a second tubes. The tubes are adapted to be disposed in operative relationship with the valve members so that flow through the tubes may be controlled thereby. Three components of the composite fluid may be separated therefrom by the present system and two components may be moved to the collection containers. The container set may further include a third collection container connected to the separation container by a tube, and a third component may thus be moved to this third container.

Abstract: A method for centrifugally separating whole blood into red blood cells and a plasma constituent rotates about a rotational axis a separation zone having radially spaced apart walls with a high-G side and a low-G side located closer to the rotational axis than the high-G side. Whole blood enters the rotating separation zone in an entry region to begin separation. Separation is halted by a terminal wall that is circumferentially spaced from the entry region. The whole blood separates into red blood cells toward the high-G side and plasma constituent toward the low-G side. The method directs red blood cells separated in the separation zone in a circumferential flow direction toward the terminal wall. The method directs separated red blood cells from the rotating separation zone through a second path that extends, at least in part, radially beyond the high-G wall.

Abstract: A removable conformal liner for a centrifuge container is described. The liner has a flexible or semi-rigid body with an opening for introducing a sample. When the liner is inserted into an internal cavity of a centrifuge container, the body of the liner conforms to the interior cavity. The liner body may be made of a material that is sufficiently resilient to allow a reversible deformation of the body by folding, twisting, collapsing, rolling, or pleating.

Abstract: An adapter for use with a centrifuge. Features of the adapter allow for less friction during extraction of the adapter and separation efficiency by preventing disturbances to the separated materials. In addition, the adapter includes features that support the walls of a sample container and prevent force from damaging the sample container during a centrifuge separation procedure.

Abstract: The claimed invention refers to a centrifuge intended for processing blood and blood components and with its function based on the effective utilisation of ring type blood processing bags with associated secondary bags and other accessories. The most outstanding feature of the centrifuge, in accordance with the claimed invention, is that its rotor, at the same intended height of the ring bag (22) inner periphery, shows at least three supports (9–11) arranged along this periphery and intended to locate the ring bag's inner strengthened periphery edge on guide holes at the same time as the centrifuge and its rotor is equipped with a joint rotating inner lid (6) which includes a clamp function (7) that clamps ring bag (22) securely along and between supports (9–11).

Abstract: A method for separating a composite fluid into components in a centrifugal fluid separation system. The system includes a rotor that has a composite fluid containment area, an inlet channel, a peripheral separation channel, outlet channels and separated component collection areas, which together form a processing area. The separation channel may be semi-spiraled. The inlet channel may connect to the center of the separation channel and an outlet channel may connect to each end of the separation channel. The outlet channels have different heights. The ends of the separation channels may have different heights. The separation channels may have extensions. The rotor may have multiple processing areas. The collection areas may be pockets slanted radially outwardly and downwardly. A motor may produce a rotating magnetic field, which co-acts with a magnetically reactive material in the rotor. A disposable bag and tubing system may be used in a processing area of the rotor.

Abstract: A centrifugal processing bag, system and method for separating the components of a mixed material is presented. The processing bag includes a hub and a first port for receiving the mixed material, where the first port includes an outlet positioned within the processing bag at a perimeter of the bag. The processing bag also including a second port having a second port inlet spaced proximate the hub and away from a central axis of the hub. The second port directs a separated material collected from the second port inlet out of the processing bag.

Abstract: A centrifuge apparatus for processing blood comprising a bottom spring-loaded support plate; a top support plate; an axial inlet/outlet for blood to be processed and processed components of the blood, the axial inlet/outlet being attached to the top support plate by a rotating seal assembly; a variable volume separation chamber mounted between the bottom support plate and the top support plate, the variable volume separation chamber being fluidly connected to the axial inlet/outlet; a pump fluidly connected to the axial inlet/outlet; and a rotary drive unit attached to the bottom support plate. The top support plate is fixed vertically and the bottom spring-loaded support plate is mounted on springs that maintain pressure on the variable volume separation chamber and allow the bottom support plate to move vertically.