Abstract: A system, method and device for continuously fractionating blood in situ. The fractionating device is connected in a closed loop to the donor and includes interleaved blood plates and blood fraction plates separated by a semipermeable membrane. Grooves in the plates direct blood flow and blood fraction collection. Uniform distribution among the plates and intraplate is obtained by manifolds.The input and output pressures of the blood pump are sensed and inputed to an microprocessor, into which donor data including weight, sex, and hematocrit is also keyed by the user. The microprocessor operates under program control to calculate, based on the donor data, the amount of plasma to be collected and the amount of anticoagulant to be added. The program controls the operation of the extracorporeal devices, regulates the operating parameters, and stops the procedure when the predetermined amount of plasma has been obtained.

Abstract: Using a membrane separating device to remove cell-free fluid from a suspension of cells to preconcentrate cells in the suspension prior to processing in a centrifuge.

Abstract: Dialysate preparation apparatus including dialysate and blood flow lines connected to a dialyzer, fluid control mechanisms on the lines to control conditions of fluid in the lines, fluid condition sensors on the lines to sense the conditions of fluid in the lines, a digital control processor receiving signals from the sensors and controlling the mechanism to achieve desired fluid conditions, and the digital monitor processor receiving signals from the sensors and verifying that fluid conditions meet predetermined safety limits.

Abstract: This invention is directed to a filtration simulator. More specifically, this invention is directed to a Dynamic Filtration Simulator (DFS) and method of determining the interaction and effect on liquid flow of additives to paper stock in a papermaking machine, which comprises:(a) admixing one or more additives to be tested with paper stock in a slurry tank to form an aqueous paper stock slurry;(b) pumping said slurry from step (a) to a filtration means comprising permeable filter material, the interior of said filtration means being in fluid communication with an exit pipe which is in fluid communication with said slurry tank, whereby aqueous slurry permeates said filter material to form a permeate and said permeate flows through said exit pipe back to said slurry tank;(c) measuring the pressure and volume flow of the aqueous paper stock slurry into the filtration means; and(d) measuring the pressure and volume flow of the aqueous permeate.

Abstract: The filter according to the invention comprises an outer casing which is provided with an end cover having a connection to the engine lubrication circuit. The outer casing houses a first filter pack or element positioned to be passed through by the engine lubricating oil. A pressure relief valve, which allows the oil to bypass the first filter pack or element in the case of excessive pressure drop, is provided. The pressure relief valve cooperates with a piston element associated with an electrically conducting spring to establish electrical connection between an electrical contact and a part of the filter casing. A second filter pack or element is positioned to filter part of the oil which the pressure relief valve allows to pass when a high pressure drop in the oil flow through the first filter pack or element occurs.

Abstract: An adaptive filter concentrate flow control system and method includes a filter system, a pumping system driving feed fluid, concentrate and filtrate flowing through the filter system and a flow control system controlling the pumping system to maintain optimum filtrate flow rates along a control curve in a transmembrane pressure--feed fluid rate--filtrate flow rate three dimensional space. Actual sensed operating point data is used to locate the control curve so as to assure an optimized filtrate flow rate at which reversible blocking of the membrane has begun to occur without irreversible plugging. The system is advantageously employed to control and maximize the flow of plasma in a plasmapheresis system.

Abstract: A membrane filter testing method comprises increasing the pressure at the primary side of a membrane filter fixedly accommodated in a housing and wetted with a liquid, by a gas at a predetermined rate, and checking whether the pressure at the primary side of the membrane filter is within a specified judging range after lapse of a predetermined period of time.

Abstract: A hemodialysis apparatus includes a sterile filter whose outlet, which is usually closed, is connected to a line leading to a discharge outlet in wherein a bypass valve is employed which can be opened at predetermined intervals both during treatment and during flushing operations. The sterile filter has a primary chamber and a secondary chamber. When the bypass valve is opened during treatment, dialysis solution flows out of the primary chamber of the sterile filter and flushes the pyrogens and particles disposed on the membranes of the filter into the discharge. No sterilizating filtration of the dialysis solution takes place through the pores of the membrane because the flow resistance present in the adjoining dialyzer, in conjunction with a degree of clogging of the pores, prevents such a flow. A ventilation means may be provided whereby the bypass circuit of the sterile filter can be ventilated. The bypass circuit may also be employed for a pressure retaining test.

Abstract: The specification discloses an externally mounted filter for filtering contaminated fluids from a fluid-containing system. Fluid is conducted from the system to a housing, through a filter element inside the housing, and back to the system. The filter includes an indicator, visible to a person viewing the housing, which is configured to assume an indicating configuration upon exposure to a fluid pressure in the filter in excess of a predetermined level. The filter is configured to discriminate between momentary fluid pressure surges and excess fluid pressure in the filter so that the indicator is not prematurely activated.

Abstract: A fluid flow chamber cassette that can be mounted with either its front wall or rear wall against a supporting machine and has a flexible tube that extends from a sidewall and forms a loop that is symetrical about a loop axis that is transverse to the side wall so that the loop will be acted upon by a pump roller on the machine both when the front wall is against the machine and when the rear wall is against the machine. Also disclosed is automatically fixing the initial liquid levels and amounts of air in venous and arterial chambers of fluid flow transfer device apparatus by having the arterial chamber inlet enter the arterial chamber at a position higher than the arterial chamber outlet, having the venous chamber inlet enter the venous chamber at a position higher than the venous chamber outlet, and priming the apparatus by causing reverse flow, so that the liquid rises in the venous and arterial chambers to the level of the entrances of the inlets.

Abstract: An immobilized-interface solute-transfer unit for transferring solute from a feed solution to an extractant liquid comprises a fluid-tight housing and a porous membrane which divides the housing into a feed solution chamber and an extractant chamber. The housing has feed solution inlet and outlet ports which communicate with the feed solution chamber, and extractant inlet an outlet ports which communicate with the extractant chamber. The solute-transfer unit also includes a presure difference controller for maintaining a difference between a liquid pressure of a feed solution in the feed solution chamber and a liquid presure of an extractant in the extractant chamber substantially within a predetermined pressure range so that an interface between the feed solution and the extractant is substantially immobilized at the membrane.

Abstract: A method and apparatus for purifying water to two different laboratory quality levels of purity, both of which are made available for dispensing. Ordinary tap water is prefiltered and treated by reverse osmosis to produce virtually salt free product water which is made available to a cabinet mounted faucet. The product water is delivered to a system of polishing cartridges which produce polished water and supply it to a special hand held dispensing gun. A recirculation pump operates to recirculate the water in the polishing system to prevent it from standing and eliminate the need for water storage. The product water is also recycled through the reverse osmosis cartridge. Some of the reject water from the RO cartridge is directed to a drain, but most of the reject water is recycled to conserve water. A microprocessor based control system monitors and displays the water quality and other conditions and generates an alarm if an abnormal condition arises.

Abstract: The disclosure describes an adapter assembly for a conventional fluid system having a filter unit mounted to a filter pad. The adapter assembly allows the pressure differential across the filter element to be conveniently measured by a differential pressure detector. The adapter assembly, which is mounted between the filter pad and the filter unit, generally comprises an adapter plate, a mechanism for attaching and sealing the adapter plate to the filter pad, a mechanism for attaching and sealing the filter unit to the adapter plate, and a fitting for connecting the differential pressure detector to the adapter plate. The adapter plate includes at least one aperture which allows fluid to flow between the inlet chamber of the filter pad and the inlet of the filter unit and another aperture which allows fluid to flow between the outlet of the filter unit and the outlet chamber of the filter pad.

Abstract: An artificial kidney comprising a haemodialyser 16 connected to a dialysis liquid circuit. The latter can be entirely integrated, that is to say that the functions previously performed by a plurality of self-contained members connected to one another are now performed by a common unit consisting of a very small number of multifunctional components. This common unit is preferably disposable. A small console groups together, with their electric circuits, the re-usable means for controlling and checking the artificial kidney.

Abstract: A system is provided for washing down equipment, aircraft and vehicles used in the application of pesticides on crops, and accumulating the wash water with its dissolved contaminants. The wash water is passed through an activated charcoal filter to remove the contaminants, and the filtered water is then converted to steam, which is also run through a second activated charcoal filter so that, with the double filtration system, only pure steam is vented into the atmosphere.

Abstract: A dialytic apparatus for single-needle dialysis comprises a first pump in the artery conduit, which first pump in the first phase conveys blood from the patient into the expansion chamber while the vein conduit is shut off. At the same time, the second pump transports blood from the expansion chamber to the dialyzer. This regulation is performed in dependence from the pressure in the vein conduit so that the pressure decrease caused by ultrafiltration is counterbalanced. In the second phase, the first pump stands still and closes the artery conduit while the second pump conveys blood out of the expansion chamber to the dialyzer at a constant rate.

Abstract: Disclosed is a system for separating impurities from a hydrogen-free fluorinated lubricant. The lubricant is passed through a filter apparatus containing an adsorbing material. The lubricant is then passed into a degasser unit to remove volatile impurities from the lubricant. The degassing unit has an area of closed suction. A pressure measuring device measures the pressure in the closed area and, based on this measurement, a control apparatus controls the degassing unit. A monitoring unit monitors the quality of the filtered lubricant.

Abstract: Apparatus for evaluating physical properties of suspensions, particularly the tendency of the solid and fluid portions of a suspension to separate under pressure. The apparatus comprises a pressure vessel having an input port, a bleeder port and a pressure measuring port. A piston is slideably mounted within the pressure vessel and has a head portion which is exposed through a retainer ring for contact by the force applying apparatus. Depending upon the design of the piston, the apparatus may be used either for the separation test described above or for a density evaluation test.

Abstract: A disposable diagnostic plasma filter dispenser includes a low cost disposable container and a rotor drive for rotationally energizing a rotor within the container. The disposable container is particularly suitable for drawing and dispensing blood samples for clinical analysis and includes a tube shaped outer wall having a frangible dispenser outlet cover, a close fitting inner tube supporting a filter membrane and a unitary rotor disposed for axel free rotation and axial translation within the inner tube in response to energization from the rotor driver. The rotor produces vortex enhanced filtration while maintaining a flow of filter fluid through the filtration gap and creating a transmembrane pressure.

Abstract: To provide a filter bypass and indicator, in a pump having an inlet and an outlet with a filter therein, a bypass port is in communication with the outlet upstream of the filter. A bypass valve assembly is provided in the bypass port and is normally in a closed position to direct all flow from the pump inlet through the filter. The bypass valve assembly opens in response to a preselected pressure differential across the filter to divert at least a portion of flow from the inlet around the filter. In addition, the bypass valve assembly includes a switch actuator and the pump includes a switch positioned in proximity to the bypass valve assembly so as to be operable in response to movement of the switch actuator.

Abstract: A separating device for separating a pair of immiscible components from a fluid mixture, such as separating water from a diesel fuel oil/water mixture, includes a housing and a filter cartridge mounted on the housing such that the filter cartridge is oriented substantially horizontally. The housing includes an inlet fitting, an outlet fitting, and a sump for receiving the fluid component separated from the mixture. Because of the orientation of the housing, the coalesced water or heavier component of the fluid mixture tends to collect in the lower portion of the filter cartridge and drains into the sump, where it may be drained periodically. The lighter component or fuel oil is communicated to the outlet port or fitting.

Abstract: A multi stage oil filter assembly is disclosed characterized by a housing including base and cover members and at least one intermediate member arranged between the base and cover members. A first planar filter member is arranged between the cover and intermediate members and a second planar filter member is arranged between the intermediate and base members. The planar faces of the base and cover members adjacent the intermediate member each contain a plurality of concentrically spaced circular grooves and a radial conduit affording communication between the grooves, whereby fluid is distributed across the planar faces of the base and cover members adjacent the planar filter members. The intermediate member contains a plurality of segmented circular concentrically spaced slots corresponding with the grooves of the base and cover member planar faces.

Abstract: An apparatus for hemodiafiltration that maintains the blood concentration of the patient relatively constant. A pump is connected to a branch off the external flow path of the dialysator which pumps fluid to the circulation system of the patient to compensate for the patient's fluid loss through the hemodiafilter membrane. A suction pump which affects the transmembrane pressure across the hemodiafilter membrane is controlled to achieve the desired filtrate flow necessary to balance the return flow to the patient.

Abstract: This invention relates to a haemodialysis device comprising a dialyzer, a reservoir of dialyzate, a cartridge for regenerating the dialyzate and a positive displacement pump with one rotor which circulates the blood and the dialyzate in two separate circuits and the conduit going from the dialyzate reservoir to the dialyzer comprises a non-return valve and a pipe which is connected in by-pass downstream of said valve and which passes through a positive displacement pump with double direction of operation and which is automatically controlled by a regulation loop.

Abstract: A contamination monitor for sensing particle contamination in a liquid system having a filter includes a sensor for measuring the pressure differential across the filter, a reference apparatus for providing information relative to at least one of the viscosity changes and the flow changes of the liquid passing through the filter by providing one or more reference signals relating thereto, and a programmable data processing and interface unit for receiving data from the sensor and the reference apparatus and providing a recognizable compensated output corresponding to the contamination level of the liquid system. The data processing and interface unit can provide a plurality of command signals for lighting a plurality of lights that can be individually used for diagnostic purposes and can provide information on the rate of plugging of the filter.

Abstract: A water treatment or processor device for household use or commercial use (for example, in a restaurant) is provided with fail-safe features in accordance with this invention to shut the treatment device "off" when an element thereof has become ineffective, such as the saturation of an adsorption element or the clogging of a filter element. Once the device is turned "off", it cannot be restarted until the depleted element has been replaced.

Abstract: A filter press (10) is supplied with material to be filtered by a filling pump (20) and a high pressure pump (26). Both pumps are connected in parallel and designed as eccentric worm pumps. The charging pressure is gradually raised to a final pressure without any temporary dropping so as to reduce the charging time to a minimum. In correspondence with the gradually decreasing absorption capacity of the filter press (10) first the normal speed of the filling pump (20) is lowered to a predetermined lower operating speed at unvarying speed of the high pressure pump (26). If required, then also the speed of the high pressure pump (26) is reduced. If the absorption capacity of the filter press (10) again increases, first the speed of the high pressure pump (26) is raised again to its former value and, if necessary, subsequently the speed of the filling pump (20) is increased again.

Abstract: The present invention relates to a device for cleaning of liquids in sand filters of the up-stream type.

Abstract: A water-deionizing system comprising a reservoir for receiving a quantity of water to be deionized, a first ion-exchanger unit capable of removing anions from said water, and a second ion-exchanger unit capable of removing cations from said water. The first and second ion-exchanger units are connected to said reservoir to form separate flow paths or circuits for circulating water from the reservoir through the units separately in parallel. The system permits efficient production of a relatively large amount of water in a batchwise operation and also facilitates the regeneration of saturated ion-exchangers.

Abstract: A differential pressure indicator is provided for detecting and indicating a clogging condition of a filter element and subsequently an opening condition of a by-pass valve. The indicator also indicates when no filter element is installed in a fluid system. A thermal lockout effective even at high internal fluid differential pressure prevents false actuation of the indicating means at low temperatures due to increased viscosity of the system fluid. A positive locking feature prevents resetting of the indicating means after actuation. Servicing of the filter element is required in order to reset the indicator.

Abstract: A device for indicating differential pressures between first and second pressure sources comprising a housing with a bore and a piston member slidably disposed within the bore and dividing the bore into first and second chambers. The piston member includes a permanent magnet and the housing includes ducts for connecting the first pressure source to the first chamber and the second pressure source to the second chamber whereby the piston member is displaceably responsive to differences in pressure between the first and second pressure sources. The device further comprises indicators in cooperative arrangement with the piston member for indicating at least first and second predetermined differential pressure levels respectively corresponding to respective displacements of the piston member within the bore. The indicators are magnetically coupled to the piston permanent magnet such that they move from non-signalling to signalling positions in response to the respective displacements of the piston member.

Abstract: In an industrial filter apparatus having a tank with an inlet receiving contaminated effluent from an industrial washing device and a discharge outlet connected to the washing device for recirculating washing fluids, a continuous filter spanning the tank interposed between the inlet and outlet, a continuous drive connected to the filter, a motor connected to the drive and a pump delivering filtered fluids from the outlet to the washing device, an automatic filter media indexer comprises a sensing arm rotatably journaled upon the tank having a contactor engagable with the filter on its downstream side connected by a link and a pull rod to a normally open switch connected to a power source and to the motor. A switch actuator on the pull rod is in registry with the switch, and an adjustable spring normally biases the pull rod.

Abstract: Process/apparatus for the processing of body fluids, advantageously comprising plasmapheresis technique for the fractionation of whole blood, features (i) means, e.g.

Abstract: A blood dialyzing apparatus having a dialyzer with blood and dialysate chambers defined therein comprises a blood pump for pumping the blood from a cannula, pierced in the patient's A-V fistula, back to the patient's A-V fistula through the blood chamber of the dialyzer, and a fluid circuit for the supply of a dialyzing solution past the dialysate chamber. The fluid circuit includes first and second shut-off valves disposed adjacent the inlet and outlet of the dialysate chamber, respectively, while a pressure sensor is provided to detect the pressure of the blood flowing upstream of the blood pump and also upstream of the blood chamber. When the pressure of the blood so detected attains a value equal to or lower than a predetermined value, the first and second shut-off valves are closed on the one hand and the ultrafiltration pressure in the dialyzer becomes substantially zero.

Abstract: A test ring for a pump strainer is threadedly attached to both a housing and a cover of the strainer in such a manner that the cover can withstand relatively high internal pressure. When the test ring is detached from the cover, the cover is adapted for quick and easy removal from the strainer housing.

Abstract: An oil filter restriction sensor device for warning the operator of an internal combustion engine when the engine oil filter has become restricted and requires replacement comprising a sensor body and a threaded adapter for mounting the sensor body between the engine mounting bracket and an oil filter having a filter element. The sensor body has passageways which allow a normal flow pattern for the oil input and filtered oil output through the filter element. A spring biased slidable piston is mounted within the sensor body with incoming oil and filtered output oil pressure applied to opposite ends of the piston. When the oil filter differential pressure exceeds a predetermined amount the piston moves to a position grounding an electrical connector causing an alarm signal to be initiated warning the operator of the restricted filter condition.

Abstract: An artificial kidney comprising a haemodialyser (a) associated with and preferably integrated into a common unit D adapted to be connected simultaneously to a patient P, to a container 34 of fresh and/or used dialysis liquid, and to a controlling and checking console (h). The disposable common unit can perform all the functions necessary for a treatment. These functions are not performed by self-contained members, but by a small number of flexible multifunctional parts, such as elements 14 and 15, each cooperating with rigid parts such as parts 10, 11, 12 and 13.

Abstract: An artificial kidney comprising a haemodialyser connected to a dialysis liquid circuit has the dialysis liquid circuit designed and simplified so as to be entirely disposable. Preferably, the haemodialyser and also all the circuits for the blood, for the dialysis liquid and for removing the ultrafiltrate are disposable. They can be delivered in a disposable container which can, during treatment, be used as a support and as a dialysis liquid reservoir. A small console includes the re-usable means for controlling and checking the artificial kidney, together with their electric circuits.

Abstract: A dialysis apparatus utilizes an expansion chamber in parallel with a pump from which the chamber receives blood via a valve. During the return flow phase the pump rotates in the same direction; but, the valve is closed and a valve at the chamber outlet is opened. The pump draws blood from the chamber and transports it to a dialyzer. A control device regulates the pump and valves depending on the time integral of the pump delivery. In each phase, blood is transported until the chamber has received or discharged a predetermined volume. The pump speed is variable during operation.

Abstract: The present invention relates to an apparatus for treating sewage sludge in which the sludge is conveyed to a vessel having an oxygen-rich atmosphere. The sludge is channelled through a first dispersing means to a plurality of second dispersing means by which it is dispersed throughout the oxygen-rich atmosphere where it is completely oxygenated. Preferably, the first dispersing means comprises separable components which define the channelling means. Preferably, the second dispersing means are aligned with the channelling means and either arranged around the inner periphery of the vessel, or attached to the first dispersing means.

Abstract: An apparatus (10) for use with a dry cleaning system having a filter for filtering the dirty solvent comprises a first pressure vessel (28) for vaporizing the filtered solvent and a second pressure vessel (58) for condensing the vapors into purified liquid solvent for collection and reuse. The upper end of the second pressure vessel (58) is upset to provide an annular chamber about the upper end of the condenser coil (76) which extends in closely spaced apart relationship into the reduced lower end of the second pressure vessel, so that clogging is avoided and better contact with the condenser coil and thus more complete condensation is achieved. In the preferred embodiment, the apparatus 10 includes a valve arrangement (104, 106, 108 and 118) by which the filter can be backflushed with hot fluid, such as steam in order to recover solvent from the saturated filter and render it safe for ordinary disposal.

Abstract: A swimming pool filter system is comprised of a pump, a filter and a water conduit means for hydraulically connecting the pump and filter in a hydraulic loop with a swimming pool. The filter is a Hayward regenerable filter wherein the diatomaceous earth coating may be periodically shaken off the filter membrane to mix with the dirt and recoat the membrane several times between cleanings to extend the time between filter cleanings. A pressure sensitive switch, mounted at the filter inlet port, closes when the inlet pressure exceeds a predetermined magnitude to energize an alarm each time regeneration is needed or after five regenerations when cleaning will be required.

Abstract: Excess or unused ink that is recovered from a printing process and which contains fibrous impurities is purified by mixing the recovered ink with virgin ink, heating the mixture to decrease the viscosity thereof, and then straining and filtering the heated mixture.

Abstract: A water filter connects into a waterline which feeds a faucet separate from the filter. A filter cartridge is seated within a canister and has an inlet and an outlet. The canister is removably attached to a cap in which is disposed an entrance port to communicate with the outlet and an exit port to communicate with the inlet. Also in the cap are an input port for receiving water from the line, an output port for delivering water into the line to feed the faucet, a passage which communicates between the input port and the exit port, a passageway which communicates between the input port and the output port and a channel which communicates between the entrance port and the output port. A diverter in the cap responds to a rate of water flow from the faucet of less than a predetermined amount for opening the passage and the channel and closing the passageway, while being responsive to a rate of flow greater than such amount for closing the passage and the channel but opening the passageway.

Abstract: Apparatus for reducing levels of organic contaminants present in water or other fluid. The apparatus includes a plurality of spaced activated carbon beds and a bed of cross-linked organic polymer particles (i.e., Imbiber Beads). The bed of polymer particles is serially disposed between the activated beds of carbon to receive and absorb organic contaminants when all the adsorption sites on the first activated carbon bed reach saturation. A second activated carbon bed receives and adsorbs contaminants which escape the absorption of the polymer particles. The polymer particles swell on contact with organic contaminants to decrease and then terminate flow of water or other fluid through the apparatus.

Abstract: A spin on fuel water separator having a filter element attached within an electrically grounded housing, means are provided for supplying an electrical potential to the filter element and the filter element is electrically insulated from the housing. Separated water is stored within the housing, and when separated water accumulates within the housing so as to contact the filter element, a current flow through the filter element, the reservoir and the housing is indicated. The housing includes a reservoir bowl provided with a warming coil which allows separated sludge and water to be warmed prior to removal from the device. An optional embodiment includes a means for detecting and indicating a restricted filter element.

Abstract: An apparatus is provided informing when a filter located in a fuel passage between a fuel tank and a fuel injection pump has clogged a predetermined amount. The apparatus is responsive to fuel pressure downstream of the filter to provide an indication when the sensed pressure is below a predetermined value. A device for draining water separated from the fuel is also disclosed.

Abstract: A blood accumulator for use in single needle dialysis systems is provided with elastic walls so that expansion of the accumulator in an outward direction may take place and in the filled condition, the walls are stretched. After the blood input pump is stopped and a valve opened, blood makes its way at a controlled rate out of the accumulator past the dialysis diaphragm back to the patient's body.

Abstract: A spin on fuel water separator having a filter element attached within an electrically grounded housing, a circuit (50) is provided for supplying an electrical potential to the filter element and the filter element is electrically insulated from the housing. Separated water is stored within the housing, and when separated water accumulates within the housing so as to contact the filter element, a current flow through the filter element, the water in the reservoir and the housing is indicated. An optional embodiment includes a pressure drop detector for detecting and indicating a restricted filter element.

Abstract: A monitoring arrangement is provided for detecting for extreme pressure conditions in blood tubing lines of a hemodialysis system. The arrangement includes a first pushbutton switch and a pivoted lever arm. A clamping means is located at a first end of the lever arm for clamping the blood tubing line against the first pushbutton switch, and the other end of the lever arm opposes a second pushbutton switch. Under low pressure conditions, the blood pressure in the tubing is no longer sufficient to hold the first pushbutton switch closed. The switch then opens to signal a low pressure condition. Under high pressure conditions, the blood tubing pressure causes the lever arm to pivot so that the far end of the lever activates the second pushbutton switch, which signals a high pressure condition.