Abstract: A cardiopulmonary bypass system utilizing membrane-based reciprocating positive displacement blood pumps (“pod pumps”). In one aspect, the pod pumps are constructed to provide reduced shear forces on the blood being pumped. In another aspect blood flow through the pod pumps can be controlled by a controller using information from pressure sensors in the control chamber of the pod pumps. In another aspect, the pod pumps are included on a disposable unit that can be received and held by a receptacle means on a base unit, the base unit also providing pressurized control fluid to the pod pumps on the disposable unit through the receptacle means.

Abstract: Fluid processing apparatuses and systems are disclosed. In some embodiments the fluid processing apparatuses include a movable enclosure, a plurality of filter housings disposed substantially within the movable enclosure, and a stand disposed within the enclosure. The filter housings are in fluid communication with one another. Each filter housing defines an elongate path and is configured to support a respective filter along the elongate flow path to filter a substantially continuous flow of fluid. The stand supports each filter housing such that the elongate flow path of each filter housing is substantially parallel to a vertical axis, wherein each filter housing is independently rotatable, relative to the stand.

Abstract: A water or liquid substance filtration device is disclosed which removes microorganisms and organic contamination and sterilizes the containers and water lines after the unit. The unit is portable, or can be mounted stationary. The unit has a five-stage filtration and sterilization system controlled by an independent onboard computer system that can link to a central computer system to keep track of all independent units. The unit will physically filter out of the water contaminants that can be reused, destroyed, or flushed down a safe drain. It can also be modified to filter for a certain size of particulate, making recovery of certain substances possible. The unit has a self-diagnostic system that can determine if the unit is operating properly and can shut down a part thereof if one of the capillary units fails. The unit uses ozone to disinfect containers and water lines.

Abstract: There is disclosed a liquid filter system that includes a liquid filter apparatus configured to self-clean without removal of the filter apparatus from the filter system. The filter apparatus uses both a filter media for filtering solids as well as a spin motion imparted to fluid being filtered so that centrifugal force can remove solids from the liquid being filtered. The liquid filter system also includes a gas pulse nozzle in fluid communication with the liquid filter apparatus and is configured to flow gas into the filter media to expel water and debris trapped in the filter media without removing the filter media from the filter system.

Abstract: A method of filtering a fluid for injection into an injection well comprises opening an actuator valve, actuating a pump in fluid communication with the actuator valve, receiving a fluid comprising solids within a filter assembly, where the pump is in fluid communication with the filter assembly, separating at least a portion of the suspended solids in the fluid within the filter assembly, ceasing separation of the suspended solids from the fluid, initiating a cleaning cycle for the filter assembly after ceasing separation of the suspended solids, washing at least the portion of the suspended solids from the filter assembly into a solids collection vessel using a cleaning fluid after initiating the cleaning cycle, and resuming separation of the suspended solids from the fluid after washing at least the portion of the suspended solids from the filter assembly.

Abstract: A method of operating hydrocyclone comprising a separation chamber which in use is arranged to generate an internal air core for affecting a material separation process, comprises measuring both a vibrational parameter of the separation chamber and a stability parameter of the internal air core during operation of the hydrocyclone. The measurements are compared against predefined corresponding parameters which are indicative of a stable operation of the hydrocyclone and an operational parameter of the hydrocyclone is adjusted dependent on the comparison.

Abstract: A fluid (i.e., generally water or wastewater) treatment system and associated methods provide for effectively treating the fluid (i.e., generally water or wastewater containing at least a plurality of salts) to provide a separated pure fluid (i.e., generally water) and a separated impurity (i.e., generally a salt). Also provided are a method for detecting or determining the need for a controlled process intervention to prevent the plugging of system components in a fluid (i.e., generally water) treatment system, and a process for preventing the plugging of the system components in the fluid (i.e., generally water) treatment system.

Abstract: Disclosed are methods of custom stabilization of the hydrogen peroxide used in the safe in-situ treatment of soil and groundwater. In one embodiment, disclosed is a method of in-situ chemical oxidation treatment of soil and/or groundwater wherein the hydrogen peroxide has been stabilized with carboxylate salt (e.g., sodium citrate, sodium malonate, or sodium phytate).

Abstract: Disclosed herein are an apparatus and method for treating ship ballast water, wherein electron beams are irradiated into the ballast water to induce radiolysis of the water, and harmful marine organisms present in the ballast water are killed by radicals produced by the radiolysis. The electron beams are continuously irradiated into the ballast water under operating conditions of an energy of 0.5-5 MeV, an electron beam irradiation dose of 0.1-30 kGy and a flow rate of 1-200 m3/hr.

Abstract: Disclosed is an operating logic of an organic material thermal hydrolysis system. One or at least two reactors are used and controlled according to a control program based on an operating logic stored in a PLC or a micro-computer to improve digestion efficiency and to minimize an amount of a sludge dehydrated cake in a dehydration process after the digestion process has been performed. Waste heat generated from a reactor is used to preheat the conditioning tank to save operating energy, and continuously generated waste heat is continuously used.

Abstract: The invention relates to a device and a method for detecting particles, in particular parasites, in drinking water adapted to on-line application. In particular, the invention b) relates to a method for detecting parasites in water, said method comprising: Passing at least a part of the water through a filter; Applying indirect sonication with ultrasound to said filter to release parasites which have been collected in said filter without disrupting said parasites; Collecting parasites for detection; and Detecting the collected parasites. This serves to collect parasites in the filter and/or increase the concentration of parasites before the filter and/or disrupt aggregates without disrupting the parasites per se. The invention further relates to a concentration device for filter filtration concentration of particles from a volume of a fluid. The concentration device comprises an ultrasonic transducer that is configured to clean the filter.

Abstract: A method and system for treating oilfield produced water is disclosed. The method includes passing oilfield produced water through a chain of filters, first filter configured to filter particles of a size larger than 10 ?m from the water, a second filter configured to filter remaining particles of a size larger than 2 ?m from the water and a third filter configured to filter remaining particles of a size larger than 0.5 ?m from the water and automatically cleaning at least one of the filters.

Abstract: Filtration systems and methods using a pump and pressure sensor are provided for improved efficiency in fluid filtration systems. A filtration system includes a pre-filter container joined to a post-filter container by a filter line having a filter. To reduce the time required for filtration a pump and pressure sensor are included in a filter inlet flow path. The pump also is used to provide air management in the system via pre-filtration evacuation of air from at least the filter.

Abstract: A method for fluid treatment that provides variable or alternative regeneration cycles within the same fluid treatment device. The duration of all stages of the regeneration cycle can be adjusted depending upon the amount of fluid treated so that regenerant resources such as water are not underutilized and waste is not discharged unnecessarily into the environment.

Abstract: A skimmer device for removal of debris and other contaminants from the surface of a body of liquid; said device including a central debris and contaminant collection element supported by outrigger buoyancy elements; said buoyancy elements ballasted by controlled charging of each of said elements with a volume of ballast liquid, and wherein an adjustment of buoyancy is provided by varying a volume of residual air retained in said buoyancy elements.

Abstract: A filter unit comprising an inlet (12) and an outlet (13) for a flow medium to be filtered, a first filter cartridge (14) having a first filter element, a second filter cartridge (15) having a second filter element, and a switching device (16) which allows alternating filter operation of the first or the second filter cartridge (14, 15). It is proposed that the first filter cartridge be a main cartridge (14) with a fine first filter element and the second filter cartridge be an auxiliary cartridge (15) with a coarse second filter element. The pressure loss in the auxiliary cartridge (15) is set to the same threshold value as a contaminated main cartridge (14), at which the differential pressure switch triggers an alarm such that during changing of the main filter, the alarm continuously sounds and is only switched off after changing the filtering back to a fine filtering operation.

Abstract: Systems and methods of controlling fouling during a filtration procedure are described. A plasmapheresis method includes accepting a selection of a plasma flow rate and predicting an estimated procedure end time based at least partially on a plasma collection target volume. The method also includes flowing blood past a membrane and changing a plasma flow rate until the selected plasma flow rate through the membrane is achieved. The method also includes determining an acceptable rate of pressure change with time for respective times to the estimated procedure end time, the acceptable fouling rate limit being associated with a system pressure and adjusting the plasma flow rate based on the determined acceptable rate of pressure change with time.

Abstract: A continuously-operable flow stream processing system and method has two or more fluid processing media arranged in a fluid conduit network to provide alternate flow paths for a flow stream to be processed (e.g. filtered). Valves and other flow control devices, e.g. controller module and sensors, are used to redirect the flow stream from one or more service-needed fluid processing media to service-ready fluid processing media without taking the system offline to remove, repair, replace, clean in situ, or otherwise service the service-needed fluid processing media, so that the system may operate continuously to process the flow stream without stoppage. Redirection into alternative flow paths and media may be automatically implemented based on a predetermined threshold or trigger condition, such as may be detected by sensors directly or indirectly monitoring media condition.

Abstract: Provided are methods of inhibiting microbial fouling and improving efficiency in biocide dosing in an industrial process containing an aqueous liquid having a biocide demand. In exemplary embodiments, the methods comprise treating an aqueous liquid having a biocide demand with a biocide, monitoring the biocide demand of the aqueous liquid, and filtering a stream of the aqueous liquid. The filtering may be performed in a full-flow or side stream manner.

Abstract: The system and process of the present invention will consist of specific monitors in tandem with interface probes reading in multiple locations, divert valves which are operated by the readings of the interface probes and online ppm monitors. Such monitors would function in conjunction with these leading indicators through a software program and computerized logic controller used to manipulate the controls of this system.

Abstract: A device for filtering for treating ballast water way and to a method for controlling same, and to a multicage-type device for filtering ballast water which automatically controls sequential backwashing and a method for same. In the multicage-type device for filtering ballast water, an automatic cleaning portion in each filtering device, in which differential pressure of at least a specific range with respect to pressure inside a body is generated, from a plurality of filtering units in the device for filtering, is sequentially actuated under the control of a control portion, thereby allowing smooth backwashing by preventing increase of back pressure during backwashing of foreign substances, and increasing repair/maintenance efficiency by installing a second pressure sensor for measuring pressure inside a filter in each of the filtering units via a pressure measurement aperture that penetrates an upper portion cover plate that covers a filter inlet aperture on the body.

Abstract: A method of preparing zirconia-containing nanoparticles and a method of preparing a composite material that includes the zirconia-containing nanoparticles are provided. A method of treating a zirconium carboxylate salt solution to remove alkali metal ions and alkaline earth ions is provided. The treated solution can be used as a feedstock to prepare the zirconia-containing nanoparticles. Additionally, a continuous hydrothermal reactor system is provided that can be used, for example, to prepare the zirconia-containing nanoparticles.

Abstract: A device and a method for operating a fuel filter (1) with a diaphragm (16) for cleaning water separated from the fuel, comprising a collecting chamber (9) for the water geodetically arranged at the bottom in a housing (2) of the fuel filter (1), are proposed, comprising at least one sensor (10, 11) each for the maximum (10) and for the minimum (11) water level in the collecting chamber (9), by means of which a valve (13) for discharging the water from the collecting chamber (9) arranged between the collecting chamber (9) and a water purification device (14) containing the diaphragm (16) is controllable.

Abstract: A method of removing unwanted molecules from blood includes (i) directing a flow of blood from a patient through a first hemofilter, (ii) removing a volume of fluid from the blood using the first hemofilter, (iii) combining a volume of first substitution fluid with an outflow from the first hemofilter, the volume of first substitution fluid being substantially equal to the volume of fluid removed from the blood using the first hemofilter, (iv) directing the combined first hemofilter outflow and the first substitution fluid volume from the first hemofilter through a second hemofilter, (v) combining a second substitution fluid with outflow from the second hemofilter, and (vi) returning the combined second hemofilter outflow and the second substitution fluid volume from the second hemofilter to the patient.

Abstract: A method and a computer program product perform a backwash process, which facilitates a reduction in a reject rate associated with a water treatment tank. If a backwash process is needed, an upper burst solenoid is operated to start an airlift flow in a first airlift path at a first position and at a first point in time, at a bottom portion of the water treatment tank, and a lower burst solenoid is operated to start an airlift flow in a second airlift path at a second position and at a second point in time. The second position is below the first position and the second point in time is after the first point in time. The airlift flow in the first and second airlift paths enables suitable water flow within the water treatment tank.

Abstract: A plasma purifying device is provided that is capable of recovering blood and plasma remaining within the plasma purifying device easily and without risk of coagulation, following completion of plasma purification therapy. The plasma purifying device has a control unit controls flow rates of the air pump and a plasma pump so that a pressure of the filtration side space of the plasma separator is higher than a pressure of the blood side space while delivering blood to the blood side space of the plasma separator by continuing to operate a blood pump without stopping following completion of plasma purification and then delivers plasma remaining in a filtration side space of a plasma separator to a blood side space of the plasma separator or to a plasma circuit by supplying air from an air pump.

Abstract: Systems and methods are disclosed for performing hemodialysis that include fluid handling systems that provide accurate control over the type and level of hemodialysis being performed. The system includes a first pump for pumping dialysate into a dialyzer and a second pump for pumping dialysate out of the dialyzer. The system also includes a third pump that provides improved control of a level of ultrafiltration, hemodiafiltration, or both.

Abstract: The invention relates to a process for monitoring the supply of substitution fluid upstream or downstream of a dialyser or filter arranged in an extracorporeal blood stream. One embodiment provides, for the detection of predilution or postdilution, for measuring the pressure in the blood stream downstream of the dialyser or filter, predilution or postdilution being recognized on the basis of the change in pressure following the shutting off and/or starting up of the substituate pump provided for conveying the substitution fluid. Another embodiment provides for recognizing predilution or postdilution on the basis of the comparison of the oscillating pressure signal attributable to the substituate pump to a characteristic reference signal. The characteristic reference signal to which the pressure signal of the substituate pump is compared is preferably the oscillating pressure signal of a blood pump arranged in the blood stream for conveying the blood upstream of the dialyser or filter.

Abstract: A method of checking and/or monitoring the correct operation of an adding device of a medical apparatus includes detecting a characteristic signal course being generated by the adding device. The medical apparatus includes an extracorporeal circuit with which the adding device is connected such that an agent can be introduced into the extracorporeal circuit via the adding device. The pressure loss in the extracorporeal circuit is measured and evaluated for checking and/or monitoring the correct operation of the adding device. The adding device for this purpose generates an oscillating pressure course.

Abstract: A system for measuring and monitoring the internal liquid within a three phase separator allows a user to accurately and reliably calculate the volumetric flow rate of the liquids exiting the three phase separator. For each liquid inside of the three phase separator, a differential pressure device is attached to where the extension fitting enters its respective liquid. Once a dump valve is actuated, the extension fitting guides its respective liquid out of the three phase separator, and the differential pressure device creates a differential pressure within the respective liquid. A sensor reads the differential pressure through a pair of sensing lines. The sensor relays the differential pressure reading to an RTU flow computer that calculates the volumetric flow rate of the liquid exiting the three phase separator. The calculation is then sent to a SCADA system, which allows the user to observe the volumetric flow rate in real time.

Abstract: An automatic filtering system for filtering a cooking medium in a fryer, includes a frypot; a filter manifold having removable filter; a pump, that supplies cooking medium from the filter manifold to the frypot; a pressure sensor that senses a pressure of the cooking medium supplied by the pump; and a controlling mechanism that controls an operation of the pump in response to the sensed pressure data. The control mechanism halts the operation of the pump after sensing a drop in the pressure of the cooking medium pressure that is greater than or equal to a predetermined pressure drop threshold. The systems and methods of the invention provide automatic filtering that may reduce or eliminate an incorrect refilling operation after the filtering of cooking medium, so that the filtering process may be performed correctly each time.

Abstract: This device serves to improve water quality under gravity flow conditions. The water quality treatment device traps floating debris with replaceable netting, it contains oil spills and settles sediment in self-cleaning settling cells above a collection bunker inside a chamber. The device directs the water below the inclined cells, through the inclined cells, or over the inclined cells, depending on the inflow intensity. All inflowing water enters the net cavity and the net is supported by the inclined cell assembly. The pollutant collection surfaces are overlapping each other and aligned with the water flow direction. A hinged baffle with orifices controls the flow rate through the inclined cells. The netting is replaceable when filled with debris through an access opening in the ceiling of the chamber. The sediment bunker is cleaned through access openings in the ceiling from the chamber inflow side and the exit side.

Abstract: An assembly and a method for filtration are disclosured, which are suitable in particular for the filtration of cells, for example tumor cells, from a sample, for example a blood sample. In the method, a pressure differential between the pressure upstream and the pressure downstream of a filter is determined; and the pressure differential between upstream and downstream of the filter is adjusted such that the pressure differential does not exceed a predetermined value.

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: A method of assessing biofilm thickness in a membrane supported biofilm reactor (MSBR) of the type comprising a lumen containing a gas phase, a liquid phase, and a gas permeable membrane providing an interface between the gas and liquid phases, the method comprising the steps of charging the lumen with an inert gas, closing the lumen to establish an initial elevated pressure in the lumen, measuring the rate of change of pressure within the lumen, and correlating the rate of change of pressure (dP/dt) with biofilm thickness. The step of correlating dP/dt with biofilm thickness involves correlating dP/dt with the rate of diffusion of the inert gas (dn/dt), correlating dn/dt with an overall mass transfer coefficient (K), correlating K with the mass transfer coefficient of the biofilm (ICB), and correlating k? with the biofilm thickness.

Abstract: A filtration unit contains a plurality of filter housings, each filter housing having a cylindrical shell with a lower port, an upper port, and a filter element. The lower and upper ports direct fluid through the filter housing in a first direction during a filtering cycle and direct fluid through the filter housing in a second direction during a backwashing cycle. The unit also includes a diverter and a servomechanism that rotates the diverter to selectively connect the filter housing to a drain port for the backwashing cycle.

Abstract: A filter assembly includes a filter body, a removable filter cartridge, and a bypass valve with incinerable and non-incinerable portions. The bypass valve includes a valve seat and a movable valve closure element removable with the removable filter cartridge and incinerable. The bypass valve includes a return member remaining in the filter body. A method is provided for controlling bypass valve-opening threshold pressure.

Abstract: An oil filter assembly is disclosed for a machine, such as an internal combustion engine, that has an oil output port and an oil input port. A mounting plate may be fixed with an outer enclosure and may be adapted for securing to the machine. The mounting plate may be further adapted to conduct oil from the machine into a peripheral portion of the outer enclosure, and then returning oil from a central portion of the outer enclosure back to the machine. Oil may pass from the peripheral portion to the central portion through a primary filter having a first porosity. A pressure-actuated valve may be fixed fluidly between the peripheral portion and central portion of the outer enclosure. Oil may pass through the pressure-actuated valve only when an oil pressure differential between the peripheral portion and the central portion of the outer enclosure exceeds a predetermined threshold pressure.

Abstract: A method of filtering a fluid, including flowing a fluid from a first side of a filter member to a second side of the filter member, the fluid containing dissolved impurities. In addition, the method includes inducing fluid cavitation within the fluid to precipitate out at least a portion of the dissolved impurities. Further, the method includes controlling a pressure differential across the filter member. Still further, the method includes, maintaining or further inducing the fluid cavitation within the fluid in response to controlling the pressure differential. Related systems are also disclosed.

Abstract: The invention relates to a multi-component part transducer assembly for determining the pressure of a fluid of interest. One part of the assembly comprises a reusable transducer, another part a disposable component comprising a flexible membrane which is in pressure connection with the fluid of interest, and another part comprises a locking component for securing the reusable and disposable parts together.

Abstract: Systems and methods are described for flushing one or more filters using a pressurized permeate stream. The permeate stream can be pressurized within a front flush unit, which can also receive a feed water stream. Energy needed to increase the pressure of the permeate stream to a pressure sufficient to cause flushing of the filters can be generated through work exchange with the pressurized feed water stream.

Abstract: An automatic filtering system for filtering a cooking medium in a a fryer, includes a frypot; a filter manifold having removable filter; a pump, that supplies cooking medium from the filter manifold to the frypot; a pressure sensor that senses a pressure of the cooking medium supplied by the pump; and a controlling mechanism that controls an operation of the pump in response to the sensed pressure data. The control mechanism halts the operation of the pump after sensing a drop in the pressure of the cooking medium pressure that is greater than or equal to a predetermined pressure drop threshold. The systems and methods of the invention provide automatic filtering that may reduce or eliminate an incorrect refilling operation after the filtering of cooking medium, so that the filtering process may be performed correctly each time.

Abstract: Apparatuses and methods for improved operation of a fluid purification apparatus. The fluid purification apparatus includes a pressure sensor to energize and de-energize one or more components of the fluid purification apparatus based on the pressure entering or in the fluid purification apparatus.

Abstract: A heat exchanger includes a heat-exchange section including a first group of tubes and a second group of tubes alternating with the first group of tubes. The first and second groups of tubes are in contact with a heat-conductive medium. In one structure, a first inlet manifold at a first end of the heat-exchange section is fluidly coupled to first ends of the first group of tubes. A first outlet manifold is isolated from the first inlet manifold and is fluidly coupled to first ends of the second group of tubes. A second inlet manifold at a second end of the heat-exchange section is fluidly coupled to second ends of the second group of tubes. A second outlet manifold is isolated from the second inlet manifold and is fluidly coupled to second ends of the first group of tubes.

Abstract: Certain disclosed embodiments concern systems and methods of preparing dialysate for use in a home dialysis system that is compact and light-weight relative to existing systems and consumes relatively low amounts of energy. The method includes coupling a household water stream to a dialysis system; filtering the water stream; heating the water stream to at least about 138 degrees Celsius in a non-batch process to produce a heated water stream; maintaining the heated water stream at or above at least about 138 degrees Celsius for at least about two seconds; cooling the heated water stream to produce a cooled water stream; ultrafiltering the cooled water stream; and mixing dialysate components into the cooled water stream in a non-batch process.

Abstract: A method of controlling a hydrocyclone system for separating a fluid mixture wherein the system includes a separator vessel for receiving the fluid mixture and performing a primary separation of the more dense and the less dense fluid phase thereby forming an interface within the separator, and a hydrocyclone apparatus having a first and second hydrocyclone compartments to separate the phases. The method includes alternating the flow rate through the hydrocyclone apparatus, alternating the interface or fluid mixture level in the separator vessel between a first level and a second level; and alternating the second hydrocyclone compartment between an open state in flow communication with the first hydrocyclone compartment and a closed state in isolation from the first compartment.

Abstract: A filter unit comprising an inlet (12) and an outlet (13) for a flow medium to be filtered, a first filter cartridge (14) having a first filter element, a second filter cartridge (15) having a second filter element, and a switching device (16) which allows alternating filter operation of the first or the second filter cartridge (14, 15). It is proposed that the first filter cartridge be a main cartridge (14) with a fine first filter element and the second filter cartridge be an auxiliary cartridge (15) with a coarse second filter element. The pressure loss in the auxiliary cartridge (15) is set to the same threshold value as a contaminated main cartridge (14), at which the differential pressure switch triggers an alarm such that during changing of the main filter, the alarm continuously sounds and is only switched off after changing the filtering back to a fine filtering operation.

Abstract: The present invention relates to a system and a process of running the system that allows for the long term filtration of product without loss of filtration capability due to clogging or fouling. The system is a normal flow filtration system having one or more filter cartridges attached to an outlet of a housing in the system. The filter cartridge(s) are contained within a bowl and depend preferably vertically from the outlet. Liquid enters the bowl of the housing and contacts the outer surfaces of the one or more cartridges. Impurities are trapped on or in the surface of the filter and the filtered liquid flows through the filter and through the outlet. One or more parameters such as flow rate, transmembrane pressure drop and/or time are measured and when the desired parameter(s) are met, the filtration ceases. A backflushing occurs back through the filter cartridges so as to remove the trapped impurities on or in the filter surface.

Abstract: A screening installation includes, provided in a flume (5) conveying a fluid flowing with a total flow QE: a screening device (10) including a screen which includes at least one filter member in order to screen a fraction Q10 of the total flow, at least one first passage (31) in the flume which is adapted to allow a fraction Q31 of the total flow to pass such that QE=Q10+Q31, so long as the head loss between the upstream side and the downstream side of the screening device is less than a predetermined value, and at least one second passage (32) in the flume which is adapted to allow a fraction Q32 of the total flow to pass such that QE=Q10+Q31+Q32 when the head loss is greater than the predetermined value.

Abstract: A fluid cassette for a blood processing system includes a cassette housing and a rigid structure. The cassette housing defines the structure of the cassette and has a fluid path at least partially extending through it. The fluid path is configured to allow a fluid to pass through the housing. The rigid structure defines a cavity that is in fluid communication with the fluid path. The rigid structure also has an interface for interfacing and/or connecting with a pressure monitoring device. The interface allows the pressure monitoring device to measure the pressure within the fluid path. The cavity has a volume of air located between the fluid path and the interface.