Abstract: A floating liquid intake for a liquid suction removal system, the liquid intake comprising housing defining an internal cavity. The housing has a hollow and buoyant annular body, an upper cover and a lower cover. The internal cavity is formed between the upper and lower covers. A substantially annular inlet is formed in the annular body for ingress of liquid into the cavity. The annular body has a buoyancy sufficient for the liquid intake to float in a liquid with the annular inlet submerged below the surface of the liquid in which the liquid intake is floating. A pipe extends into the cavity and the pipe includes an inlet that in use is open below the surface of the liquid within the cavity. The pipe extends outside of the cavity for connection to a liquid suction removal system.

Abstract: A device having a funnel structure (connected to a separating arrangement by a base pipe is disclosed. The base pipe is horizontal and arranged between the funnel structure and the base pipe. The base pipe is also a vertical suction pipe. The device includes a pressure pipe which is parallel to the base pipe. The funnel structure is slightly below the water surface. In operation, water and floating waste pass over the edges of the funnel structure and swirl into the suction pipe. A jet of water may be injected through the pressure pipe to the base pipe. A flow gradient may then be formed in the base pipe and the differently sized waste objects may separate. If the water contains liquid waste, the speed of the water jet may be adjusted in such a way that the liquid waste and water do not form an emulsion.

Abstract: A water-oil separation device uses a difference in density between water and oil. The water-oil separation device can easily and quickly separate oil by using a polymer film floating at interface between water and oil. The water-oil separation device easily and quickly collects oil of various viscosities with a simple structure by using differences in density between materials without using a conventional lyophilic/lyophobic film, thus solving the drawbacks of conventional filter-based and adsorption-based methods, and enabling quick and effective responses to actual oil spill situations.

Abstract: A skimmer apparatus is provided to separate a less dense upper liquid layer from on top of a denser lower liquid layer. The skimmer apparatus includes a skimmer vessel at least partially submerged within a fluid and preferentially receive the less dense fluid. A first conduit is located within the skimmer vessel by a plurality of support arms. The plurality of support arms affixes the first conduit's vertical and radial location within skimmer vessel. In use, the skimmer height is set to collect the less dense fluid into the skimmer vessel. A lower end of the first conduit is in fluid communication with the inside of the skimmer vessel and the collected fluid therein. An upper end of the first conduit is configured for being suctioned thereby withdrawing fluid from the skimmer vessel.

Abstract: A device for manipulating magnetic particles includes a gelled medium layer and liquid layers alternately stacked in a tubular container along a longitudinal direction of the container. A magnetic particle movement portion for moving magnetic particles exists along an inner wall surface of the container, and the magnetic particle movement portion extends along the longitudinal direction of the container. At a portion where the gelled medium layer is loaded, the cross-sectional shape of the container inner wall in a plane perpendicular to the longitudinal direction of the container is non-circular, and the shape of the magnetic particle movement portion in the cross section is a curved shape or an angular shape.

Abstract: A system for automated simultaneous measurements of multiple parameters (mechanical, electrical and/or thermal) of biological tissues includes a base platform supporting a biochip holder module with a biochip integrated therein and an indenter for nano- and micro-scale indentation of a tissue. The biochip is formed with an array of micro-sensors, for example, electromechanical micro-sensors integrated on a substrate of the biochip. A temperature microsensor maybe additionally formed, for example, on the tip of the indenter to measure thermal characteristics of the tissue specimen heated by the micro-heater fabricated on the biochip.

Abstract: A scum filtration system is used to separate, collect, capture, and remove surface scum and contaminants from a body of standing water. The scum filtration system includes at least one treatment assembly, a pumping system, and a main support structure. The at least one treatment assembly is used to filter scum, contaminants, and other similar material from a body of water such as, but not limited to, a pond or lake. The pumping system is used to drive water from a pond or lake into the at least one treatment assembly. The main support structure is used to support the at least one treatment assembly. Further, the main support structure is used to maintain the arrangement of the at least one treatment assembly.

Abstract: A buoyant hydrodynamic pump is disclosed that can float on a surface of a body of water over which waves tend to pass. The pump incorporates an open-bottomed tube with a constriction. The tube partially encloses a substantial volume of water with which the tube's constriction interacts, creating and/or amplifying oscillations therein in response to wave action. Wave-driven oscillations result in periodic upward ejections of portions of the water inside the tube that can be collected in a reservoir that is at least partially positioned above the mean water level of the body of water, or pressurized by compressed air or gas, or both. Water within such a reservoir may return to the body of water via a turbine, thereby generating electrical power (making the device a wave engine), or else the device's pumping action can be used for other purposes such as water circulation, propulsion, or cloud seeding.

Abstract: Disclosed herein is a device for improving the quality of rainwater/stormwater by removing pollutants therefrom. The device comprises a substantially cylindrical tank having an inlet for entry of water and an outlet for discharge of water. A coarse filter is provided in the tank for filtering gross pollutants from inflowing water, the coarse filter dividing the tank into an upstream first region/chamber and a downstream second region/chamber. A fine pollutant discharge opening is located between the coarse filter and the outlet. A valve comprising a valve member for opening and closing the fine pollutant discharge opening is configured to automatically open the fine pollutant discharge opening to discharge an initial volume of the water passing the coarse filter, the valve member being biased toward a configuration for closure of the fine pollutant discharge opening during an inflow event. The water passing through the fine pollutant discharge opening bypasses the outlet.

Abstract: A pool cleaning robot that may include first and second fluid openings, with a fluid path between the first fluid opening and the second fluid opening; a turbine at least partially disposed within the fluid path so as to extract energy from flow of fluid through the fluid path; an electrical generator; a rechargeable power source; and a controller that is arranged to direct the pool cleaning robot to be positioned in a certain location in which a flow level of fluid that is circulated by a pool fluid circulation system is higher than a flow level of the fluid within a majority of the pool, wherein when positioned at the certain location the fluid that is circulated by the pool fluid circulation system passes through the fluid path.

Abstract: A power plant which operationally combines a downstream turbine unit (7) and an upstream grating assembly (8), includes a grating (16), a supporting structure (17), and an element (18) for associating the grating (16), which has a structure that enables movement of at least the upper portion of the grating (16) between an upright position for the debris-stopping function and a folded-down position for discharging the floating debris stopped by the grating (16).

Abstract: The present invention relates to an energy transforming unit adapted to convert reciprocating forces (Fl) into rotating axle movements on at least one force transmitting axle and/or into electrical power. The unit comprises at least one restriction device (3, 4, 5) which is directly connected to the force and which is arranged to forward the incoming reciprocating forces (Fl) into a movement over at least one conversion module (2a-d, 56, 64, 73, 80, 81, 87, Cm). The energy transforming unit is characterized in that the at least one restriction device (3, 4, 5) is delimiting one, by the energy transforming unit enclosed reciprocating volume which entirely or partly passes through the at least one conversion module (2a-d, 56, 64, 73, 80, 81, 87, Cm).

Abstract: A method and device for extracting fluid from a body of fluid is has a bellows with a feed system interfaced to a first end of the bellows. A floating head is interfaced to a distal second end of the bellows and has one or more buoyancy elements. The buoyancy elements cause the floating head to float at a surface of the fluid. One or more inlets on a lower surface of the floating head are in fluid communication with the distal second end of the bellows, such that, fluid from a stratum beneath the surface of the fluid is drawn into the inlet(s), passes through the bellows, and into the feed system.

Abstract: A traveling screen machine having an active screen section arranged transverse to the flow direction of a liquid stream is suggested, wherein the endless screen belt is formed as an endless screen belt that is flexibly foldable, compressible or bendable transverse to its direction of movement.

Abstract: An oil collecting apparatus is provided to recover polluted nature environment and to keep nature environment clean in such a way that oil leaked over river or ocean is effectively collected on the spot, and only the oil is removed by separating water and oil, wherein the volume of the water tank configured to separate water and oil can be reduced in half, so the present invention may be applied to a small size ship, and only the oil leaked over river and ocean may be separated and collected on the spot. A water surface cleaner with an excellent oil connecting capacity may be built using the present invention.

Abstract: A device is provided for removing clarified water from a basin. The device includes a water receiving unit associated with a float. The float and water receiving unit is disposed over a pipe assembly. The float and water receiving unit is moveable up and down and, in the process, the telescoping pipe assembly retracts and expands. Water received by the water receiving unit is directed through the pipe assembly to an outlet.

Abstract: A mechanical separator for separating a fluid sample into first and second phases is disclosed. The mechanical separator includes a float, a ballast assembly longitudinally moveable with respect to the float, and a bellows structure. The bellows structure includes a first end, a second end, and a deformable bellows therebetween. The float is attached to a portion of the first end of the bellows structure, and the ballast is attached to a portion of the second end of the bellows structure. The attached float and bellows structure includes a releaseable interference engagement therebetween. The float has a first density, and the ballast has a second density that is greater than the first density of the float.

Abstract: A device for regulating flow provided to work with a skimmer (12) in a pool, particularly a swimming pool, the skimmer including a peripheral frame (16) and providing a window (14), characterized in that it includes a base having a negative floatability and a flap having a positive floatability, articulated relative to the base, the whole having a positive floatability so that the upper edge of the flap is even with the surface of the water.

Abstract: A subsurface hydrocarbon capture apparatus having a filtration member connected to a mouth frame, wherein the filtration member is composed of a material that is hydrophobic and lipophilic, the apparatus having buoyancy and weight members to maintain the apparatus in a subsurface disposition when pulled by a boat.

Abstract: A buoy or float can be positioned within a separation container to assist in a physical separation of components of a whole material positioned in the separation container. The buoy can be positioned within the container to move from between and separation a first end and a second end of the container substantially unaffected by a portion of the whole material, including a clotted portion thereof. A first port can be provided near the first end of the container for introduction of the whole material and a second port can be provided near the second end of the container for removal of at least a portion of a separated material.

Abstract: This disclosure is directed to systems for separating a target analyte from a suspension. A suspension is added to a tube. A float is also added to the tube, and the tube, float, and suspension are centrifuged together, causing the constituent components of the suspension to separate into different layers along the axial length of the tube according to their specific gravities. The float has a specific gravity that positions the float at approximately the same level as a layer containing the target analyte, when the tube, float and sample are centrifuged. Prior to isolation, the material may be located between an outer surface of the float and an inner surface of the tube, or within a central bore that extends longitudinally through the float. The target analyte may then be drawn into a compartment within the float, thereby isolating the target analyte from the other suspension constituents.

Abstract: Described are methods and systems for filtering and capturing waterway wastes. The system can include a bottom section that can remain stationary irrespective of the height of a waterway surface, a side section, a top section that adjusts in response to a change in the height of the waterway surface, a waste capture apparatus for collecting waterway waste, a floatation device, and a first mounting device. The method can include the steps of providing a waterway waste capturing device including top and bottom sections, adjusting the height of the top section based on the height of the waterway, and collecting waterway wastes. By filtering and capturing waterway wastes in accordance with the inventions provided herein, one can efficiently and effectively improve the manner in which wastes and other debris are removed from a waterway, thus mitigating the wastes' adverse environmental effects and significantly decreasing the cost of its removal.

Abstract: The water aerator using a compressed gas container is a self-contained unit having a float and a container of compressed gas (e.g., air, oxygen, etc.) installed beneath a perforated diffuser plate that, in turn, is positioned below the float. High-pressure gas from the container flows through a pipe or tube to a regulator valve and pressure gauge at the top of the pipe. A larger diameter low-pressure pipe or tube is placed concentrically about the high-pressure pipe. Regulated low-pressure gas flows down through the outer low-pressure pipe to a dispensing nozzle below the diffuser plate, whereupon the gas flows upward and is broken up by the perforations in the diffuser plate to form smaller aeration bubbles. An electrical power source, pressure switch, and light may be provided to indicate when the compressed gas container is depleted. The device may be motorized.

Abstract: A system and process for continuously and immediately removing contaminants from wastewater and treating wastewater, where the wastewater is treated to supply fluid that can be reused in the cleaning system or discharged safely into the environment is disclosed. The system and method comprises one or more pumping means for circulating and recirculating fluids captured or collected by the system to one or more of the processes in the system, such as wash water applications or further treatment cycles. According to one embodiment, the wastewater is transported through purification sections of the device. Depending on the system used, these sections could include several of the following: pretreatment to remove debris and certain heavy solids; treatment by methods such as a conductivity solution injection system and/or electrolytic coagulation system, a polymer injection system, and a inline mixer for mixing the polymer in the wastewater stream; and an ozone treatment system.

Abstract: A blood specimen processor by means of which blood specimens are collected into a collection tube containing an anticoagulant and a molded buoy of predetermined density between 1.045 and 1.084 with an embedded water swellable o-ring that expands to form a robust seal in a leucocyte density gradient between the buoy's outer surface and tube's inner surface. The buoy is made of a first resin and a second resin, the first resin having a lower density than the second resin, the first resin and the second resin being present in such amounts and relative proportions so that the body has an overall density between 1.045 and 1.084 and preferably, a center of gravity below a geometric center of the body. When the blood specimen contained in the processor is centrifuged, the buoy is thrust through the separating blood and the developing interface of erythrocytes, leucocytes, and plasma.

Abstract: Some embodiments include a valve positioned within a test tube to maintain a separation between components of liquid with different densities after centrifugation. The valve preferably includes a cylindrically shaped housing with a conical plug configured to nest within the housing. The plug is not in contact with the housing during centrifugation, but comes into position post-centrifugation.

Abstract: An aerobic bacteria waste digester uses a rocking paddle to mix a waste fluid. A pair of spaced-apart inflatables engaged with the paddle and alternately inflated provide buoyancy forces to drive the rocking action. The paddle has two decks and a peripheral skirt. The paddle is of a trestle-type construction with light weight planks forming the decks. The position and motion of paddle surfaces and air bubbled through the fluid from below, is able to enhance bacteria colony growth and thus the rate of bio-mass digestion.

Abstract: A drainage device for draining liquid out of a closed chamber includes a main body, a piston assembly, and a transmission assembly. The main body defines a receiving chamber and a liquid inlet communicating with the receiving chamber to the closed chamber. The piston assembly is fixed in the receiving chamber of the main body. The transmission assembly is partially received in the receiving chamber. The transmission assembly and the piston assembly cooperatively separate the receiving chamber to a first chamber adjacent to the liquid inlet and a second chamber away from the liquid inlet. The transmission assembly is slidably received in the receiving chamber, thereby causing air pressure differences between the first chamber and the second chamber, to pump the liquid from the closed chamber to the second chamber. The main body further defines a plurality of discharge holes for draining liquid out of the second chamber.

Abstract: A drainage device includes a closed chamber, a liquid pumping mechanism, and a liquid discharge mechanism. The drainage device can also include a controller. The closed chamber may be filled with liquid and gas for discharge. The liquid pumping mechanism pumps the liquid in the closed chamber, and prevents the liquid in the liquid pumping mechanism from flowing back to the closed chamber. The liquid discharge mechanism discharges the liquid in the liquid pumping mechanism to the outside, and prevents outside air from flowing into the closed chamber.

Abstract: The present invention is a storm water filter system for filtering floatable debris and non-floating pollutants from storm, water passing through a storm water drain system vault. The storm water filtering system has a vault having chamber having a floating skimmer panel between the inlet thereto and the outlet therefrom. The skimmer panel has a filter passageway therethrough for filtering the storm water while the floatable skimmer panel captures floatable debris and trash from the storm water. Storm water entering the vault inlet passes through a filter element in the skimmer panel and out the vault outlet and also can pass under the floating skimmer panel when the floatable skimmer panel is floated to a raised position to thereby prevent storm water from accumulating on the inlet side of the wall.

Abstract: The present invention is a storm water filter system for filtering floatable debris and non-floating pollutants from storm water passing through a storm water drain system vault. The storm water filtering system has a vault having chamber having a wall between the inlet thereto and the outlet therefrom. The wall has a filter passageway therethrough for filtering the storm water and a floatable baffle panel covering a second passageway therethrough for capturing floatable debris and trash from the storm water. Storm water entering the vault inlet passes through a filter element and out the outlet and also can pass under the floating baffle panel when the floatable baffle panel is floated to a raised position to thereby prevent storm water from accumulating on the inlet side of the wall.

Abstract: A skimmer system for removing a substantially liquid substance such as oil floating on the surface of a body of water has a reservoir body defining an collected fluid reservoir and having a primary weir edge. A weir tube extends upwardly within the reservoir and provides a secondary weir edge being of less height than the primary weir edge and defines a vortex chamber. A plurality of buoyancy members support the reservoir body in relation to the surface of the body of water and are adjustable relative to the reservoir body by power operated or mechanical devices for selective positioning of said primary weir edge relative to the water surface. A pump having a suction inlet is in communication with the vortex chamber and has a discharge outlet conducting recovered oil to a collection barge. A power source such as a hydraulic fluid supply is connected in driving relation with the pump.

Abstract: The present invention is a nutrient separating baffle box having a screened filter basket therein for a storm water drain system and especially to a screened filter basket having floating bypass panels to allow the capture of floating debris in the filter basket and when the basket cannot pass enough water flow therethrough to thereby allow bypass of storm water while retaining floating debris in the filter basket.

Abstract: An apparatus having flotation ballasts, a flotation platform and on the flotation platform, an intake equipment, such as a screen, check valve and/or pump intake and a coupling for a discharge pipe. In an embodiment of the present invention comprises, there are a plurality of substantially symmetrical flotation ballasts, each having a ballast chamber. The composition of the flotation ballast may be made of a material having a density appropriate for the fluid in which it is to be submerged. The method includes the steps of using an apparatus as herein described to ascend and descend intake equipment.

Abstract: A floating element for separating components of a physiological fluid comprises two parts that are relatively movable. The two parts define a prescribed volume between them when at their maximum separation, and one of the parts may be moved toward the other to express the fluid contained in the volume between the parts. The parts are made of materials having densities so that they assume a desired position in the fluid to allow selected components to be easily obtained and expressed.

Abstract: A system and method for cleaning oil spills from the surface of a body of water involves deploying a plurality of remotely guided self-propelled floating liquid hydrocarbons collection and separation apparatus, floating liquid hydrocarbons retention booms and floating liquid hydrocarbons storage devices, moving the liquid hydrocarbons boom to contain the liquid hydrocarbons, moving the liquid hydrocarbons collection and separation apparatus by remote guidance into the contained liquid hydrocarbons and operating the apparatus to separate the liquid hydrocarbons from the water, and pumping the separated liquid hydrocarbons into the floating liquid hydrocarbons storage devices.

Abstract: Apparatus (10) for removing sludge from a liquid reservoir, the apparatus (10) comprising buoyant float means (12), a sludge pump (24) mounted via a support arm (17) and the apparatus (10) having an upper profile so as to allow it in use to operate beneath a membrane covering at least part of the reservoir. The support arm (17) may be oscillated to move the pump in a substantially vertical plane. The buoyancy of the float means (12) may be adjusted to vary the position of floating of the apparatus (10) in the liquid.

Abstract: A polar liquid mixture containing suspended or dissolved particles or solute is exposed to air or a hydrophilic surface. An exclusion zone having a reduced concentration of particles or solute is formed in the polar liquid adjacent to the interface with air or the hydrophilic surface. One or more fractions of purified polar liquid and/or concentrated particles or solute are collected. A sensor can provide feedback to the collector.

Abstract: An apparatus for buoyancy driven filtration includes a tank and a filter assembly. The tank preferably includes a cylindrical sidewall, a circular base and a roof. The sidewall extends upward from the perimeter of the base wall and the roof extends across the top of the sidewall. A travel stop extends downward from the roof. A liquid feedstock flows through a storm water inlet. At least one overflow port is provided through the sidewall. The filter assembly includes a filter element and at least one buoyancy element disposed on a bottom of the filter medium. As water flows through the storm water inlet, the water finds its level above the filter medium to provide a liquid feedstock, some of which penetrates the filter medium to create a filtrate. As the tank fills, the filter assembly rises on top of the filtrate as provided by the buoyancy element.

Abstract: A floating oil skimmer and gravitational separator system, consisting of a vessel adapted to be submerged in a body of water. Oil/water are drawn through the floating skimmer head by a water pump, pumping water through the skimmer head as water is pumped out of the vessel from the bottom of the vessel. The improved skimmer head design improves control of the skimmer head buoyancy and stability, thereby more consistently bringing oil/water into the vessel. An improved means of coalescence and collection of oil into the top of the inside of the vessel is also disclosed, where the oil once collected is then pumped out of the vessel for storage and the water is returned to the water body. Methods of manufacturing the system are also disclosed.

Abstract: A floating suction head assembly for use with a hose, for drawing liquid into the hose. The assembly includes a float and a strainer rotatably mounted to the float. The strainer has a coupling portion for coupling to a hose.

Abstract: The apparatus of this invention consists of a float assembly, constrained in its vertical movement by a perforated riser. The riser is surrounded by a flexible, bellows conduit which will allow the float assembly to move up and down the vertically disposed riser. The float assembly supports a weir collar designed to allow multiple weir orifice openings of different sizes. The flexible, bellows conduit is watertight, and prevents water from entering the riser below the float assembly that is buoyed just below the surface of the liquid basin. The riser is connected to an outlet that discharges the liquid from the liquid basin.

Abstract: A driven decanter assembly for a wastewater primary treatment system, comprising a longitudinal decanter disposable in the wastewater and having a longitudinal trough and a horizontal entrance weir, a polygonal or arcuate screen attached to the decanter and having at least two screen surfaces disposable below the surface of the wastewater outside of the trough, and a floating baffle pivotably mounted to the decanter and disposable in the wastewater outside of the screen. The driven decanter assembly can directly replace a prior art driven decanter in any waste water primary treatment system.

Abstract: The present invention is a storm water filter system for filtering floatable debris and non-floating pollutants from storm water passing through a storm water drain system vault. The storm water filtering system has a vault having chamber having a wall between the inlet thereto and the outlet therefrom. The wall has a filter passageway therethrough for filtering the storm water and a floatable baffle panel covering a second passageway therethrough for capturing floatable debris and trash from the storm water. Storm water entering the vault inlet passes through a filter element and out the outlet and also can pass under the floating baffle panel when the floatable baffle panel is floated to a raised position to thereby prevent storm water from accumulating on the inlet side of the wall.

Abstract: A vacuum skimmer for ponds, swimming pools or similar bodies of water has housing with an intake opening and a dirt collecting container arranged downstream for collecting coarse materials. The water to be purified is sucked in through the dirt collecting container by a pump arranged downstream. The intake opening is provided on one housing side. The vacuum skimmer is movable in such a way that the intake opening upon operation of the vacuum skimmer can orient itself in different directions. The vacuum skimmer has an aeration device by means of which air can be blown into the water.

Abstract: A gravity separator S separates a liquid phase O and a gas phase G from a multiphase fluid mixture E. The gravity separator comprises a collector 1 for collecting the liquid phase O, an outlet 8 for extracting the gas phase G and a draining circuit 3 coupled to the collector 1 for draining the liquid phase O out of the separator. The gravity separator S further comprises a floating assembly 2 coupled to the collector 1. The floating assembly is arranged to float at an interface GLI between the liquid phase and the gas phase so that the collector is positioned in the multiphase fluid mixture present in the gravity separator S for collecting substantially the liquid phase O.

Abstract: A filter assembly has an inlet for supplying a fluid to be cleaned and an outlet for returning cleaned fluid. A cloth filter is disposed between the inlet and the outlet. The filter has a web of filter cloth wound on a supply roll and guided along an effective filter area to a takeup roll for receiving clogged filter web. A motor is connected to the takeup roll for rotating the takeup roll and for transporting the filter cloth forward across the effective filter area. A switching device is connected to selectively energize the motor and to index the filter cloth forward by an amount less than a length of the effective filter area.

Abstract: An exemplary apparatus (100), for removing buoyant pollutants from a polluted coolant, includes a collecting device (10) and a removing device (20). The collecting device includes a pollutant collecting structure (11) and a bi-directional pump (12). The pollutant collecting structure includes a hollow tub (112) and a collecting module (113) slidable relative to the hollow tub. The bi-directional pump communicates with the hollow tub and the removing device. The removing device includes a filter (21) and a pollutant removing structure (22) disposed on the filter. The filter includes a filtrating unit (211). The filtrating unit is partitioned into a first cavity (2132) and a second cavity (2133) by a partition sheet (213). The partitioning board defines a communicating gap (2131) for the first cavity and the second cavity to communicate with each other. The pollutant removing structure includes a removing member (221) for removing the buoyant pollutants out of the filter.

Abstract: A water collection device for collecting clarified water in a basin. The collection device includes a floating ring having a water inlet recessed within the central portion of the floating ring. The water collection device is configured to facilitate a greater flow of water into the water inlet from one peripheral zone than another peripheral area or zone around the floating ring.

Abstract: A floating element for separating components of a physiological fluid comprises two parts that are relatively movable. The two parts define a prescribed volume between them when at their maximum separation, and one of the parts may be moved toward the other to express the fluid contained in the volume between the parts. The parts are made of materials having densities so that they assume a desired position in the fluid to allow selected components to be easily obtained and expressed.