Abstract: Apparatus for generating foam for use in fire fighting having two plates housed in a chamber which respectively introduce pressurized air and a water/surfactant solution between the two plates where foam is generated and emitted from an aperture on the side of the chamber. The pressurized water/soap solution enters the chamber through an orifice in one plate. Pressurized air enters the chamber through a number of channels bored through the other plate, such channels appearing in an annular groove which circumscribes the water inlet. The plates are provided with surfaces which are brought together to form a restricted area therebetween. The restricted area balances the pressure between the incoming water and the incoming air by achieving an equilibrium at some particular radius out from the center of the two plates. This equilibrium radius moves in and out from the center as necessary to keep the two pressures balanced.

Abstract: Apparatus for generating foam for use in fire fighting having two plates housed in a chamber which respectively introduce pressurized air and a water/surfactant solution between the two plates where foam is generated and emitted from an aperture on the side of the chamber. The pressurized water/soap solution enters the chamber through an orifice in one plate. Pressurized air enters the chamber through a number of channels bored through the other plate, such channels appearing in an annular grove which circumscribes the water inlet. The plates are provided with surfaces which are brought together to form a restricted area therebetween. The restricted area balances the pressure between the incoming water and the incoming air by achieving an equilibrium at some particular radius out from the center of the two plates. This equilibrium radius moves in and out from the center as necessary to keep the two pressures balanced.

Abstract: A column of solvent containing foaming contaminants is provided. Gas is injected into the solvent in the column so as to generate foam in the column. Foam generation continues so as to push the foam up in the column, wherein much of the solvent that is in the foam is allowed to drain back down into the column. The drier foam is pushed out of the column and into a container. The foam is broken up into gas and the liquid foaming contaminants. The gas is vented and recirculated for injection into the column for foaming purposes. A portion of the liquid in the container is recirculated as a spray, which spray breaks up the foam. Another portion of the liquid in the container is recirculated into the column as reflux. Another portion of the liquid in the container is removed from the system in order to remove foaming contaminants therefrom.

Abstract: A foam of very small, microscopic bubbles of surfactant, each bubble containing a small quantity of water, is mixed with a water/cement mixture having a water to cement ratio of less than 0.33. The small bubbles have a ball bearing effect on the smaller cement and sand particles, increasing plasticity or flowability and thus reducing the water requirements of the mixture. The foamed cement mixture is laid to form a desired concrete structure, and the bubbles disintegrate or transform to leave voids of similar size uniformly dispersed throughout the concrete structure.

Abstract: A device for generating foam by the Venturi effect mixes liquid and gaseous phases. The device has a liquid insertion nozzle on the same axis as a Venturi stage having a converging portion disposed facing the nozzle, a throat of diameter "D", and a gas inlet coaxial with the nozzle and in communication with the converging portion. In operation, the gas is sucked in by the Venturi effect and directed towards a mixing chamber connected to a foam outlet. Mixing between the two phases takes place in a free jet, and the diverging portion of the Venturi has at least three zones of progressive cone angles, with discontinuities between the zones giving rise to a cavitation phenomenon, and opening out into a turbulent chamber.

Abstract: A foam generating apparatus and system for generating high quality foam suitable for dust control is disclosed. The apparatus is an eductor that makes use of the energy of a high pressure stream of aqueous foaming solution to draw air into the foaming solution and force it through a foam generator. A dust control foam system is described which employs such air eductors. The described foaming system requires only a single pressurized line to supply foaming solution obviating the need for a compressed air line.

Abstract: An expansion device for doing work comprised of a housing including first and second selectively expandable sections defining an internal chamber which contains a chemical motor. Upon activation of the chemical motor, the first and second chamber are driven apart with sufficient force to allow the device to do work. The chemical motor is generally an irreversible reaction which causes the expansion device to be maintained in an expanded position.

Abstract: Low-pressure gas is mixed in a viscous material. The flow of the gas can be easily controlled so that the dispersion of the mixing ratio of the viscous material to the gas may be confined within a small tolerance and fine bubbles may be uniformly distributed in the interior of the viscous material. The gas is mixed in the viscous material by a first pump, from which a mixture of the gas and the viscous material is delivered. Pressure is applied to the mixture by a second pump. The gas is distributed in the interior of the viscous material by allowing the mixture under pressure to pass through a conduit assembly. The viscous material is foamed when the mixture is discharged from a nozzle through a discharge pipe.

Abstract: In injection of steam, gas, liquid or a powdered or granulate product into a fluid in an injection apparatus having a substantially disc-shaped rotor (53), a product inlet (50) and a central product outlet (57), the injection is carried out in an annular injection zone above the disc-shaped rotor (53) at a distance from both the circumference and the center of the rotor (53). The fluid product which may be a liquid with considerable variation of dry solids content and viscosity is exposed to a radial displacement effect as well as a tangential dispersion effect.

Abstract: A filter device and method of filtering components from a surgery plume. The filter device comprises an integral solution reservoir which intercepts an airstream passage and airstream and cooperates with the airstream to direct air and solution into pads to create a foam. The foam created by the pads and solution and additional elements of the filter react with one or more undesirable components of the surgery plume to cleanse the airstream prior to exhaustion into the atmosphere. No separate solution supply or delivery system is necessary.

Abstract: A foam producing apparatus has a first mixing chamber with an inner subchamber connected to a supply of gas at a first pressure and an outer subchamber connected to a supply of a foamable liquid at a second pressure higher than the first pressure. A plurality of orifices connect the outer subchamber to the inner subchamber. The foamable liquid is forced from the outer subchamber into the inner subchamber through the orifices and is atomized to form droplets carried by the gas to an outlet. A second mixing chamber is connected to the outlet of the first mixing chamber and is filled with an agitating medium so that droplets propelled through the second mixing chamber are violently agitated to produce the desired foam.

Abstract: A method and device are described for the production of foams from two-component reactive mixtures using carbon dioxide as expanding agent, by mixing at least one of the reactive components with carbon dioxide under pressure. That mixture is then mixed with the other reactive component(s) to form a foamable reactive mixture, which is expanded and cured to form the final product. The foamable reactive mixture is expanded to ambient pressure through at least one fine-meshed screen (21a, 21b, 21c).

Abstract: A structural foam billet made from a plurality of blobs of foam forming stock which are spaced from one another in a predetermined order and expanded into the structural foam billet.

Abstract: Apparatus for generating foam for use in fire fighting having two plates housed in a chamber which respectively introduce pressurized air and water/soap solution into the space between the two plates where foam is generated and emitted from an aperture on the side of the chamber. Pressurized water/soap solution is introduced through an orifice into a small opening through one plate. Pressurized air is introduced into the other plate through a number of channels bored through the plate to an annular grove on the surface of the plate. The plates are provided with flat surfaces which are brought together to form a narrow gap. The narrow gap balances the pressure between the incoming water and the incoming air by achieving an equilibrium at some particular radius out from the center of the two plates. This equilibrium radius moves in and out from the center as necessary to keep the two pressures balanced.

Abstract: An apparatus for continuous production of finished foam material, in which the proportions of the constituents are monitored and continuously adjustable during operation of the machine. The liquid components are metered by positive-displacement, progressive-cavity, screw-type pumps driven by variable speed motors. Rates of flow are monitored by flow meters, and the relative proportions of the constituents can be closely adjusted by varying the speeds of the pump drive motors and observing the flow meter readouts. The finished foam produced by the apparatus may be used, for example, for the preparation of foamed cement grouts or for fighting fires.

Abstract: A method and device are described for the production of foams from two-component reactive mixtures using carbon dioxide as expanding agent, by mixing at least one of the reactive components with carbon dioxide under pressure. That mixture is then mixed with the other reactive component(s) to form a foamable reactive mixture, which is expanded and cured to form the final product. The foamable reactive mixture is expanded to ambient pressure through at least one fine-meshed screen (21a, 21b, 21c).

Abstract: The invention relates to a muco-adherent, soluble device for administering active ingredients, a method of using said device, and an improved method of manufacturing said device using a continuous, enclosed mixing device capable of operating under pressure. The devices of the invention, which comprise a lyophilized foam and an active ingredient, have a dissolution time of at least about 8 hours, and preferably at least about 24 hours, and can provide for the sustained and/or controlled release of an active ingredient for up to about 24 hours.

Abstract: An apparatus for generating foam includes a power source such as an internal combustion engine mounted in a frame for portable transportation of the apparatus. The power source drives an air compressor through an electric clutch which can disconnect the air compressor and a water pump. The water pump generates flow of the water under pressure through a duct system either to a water discharge valve or to a foam discharge valve. The foam is generated by injecting into the water stream a surfactant which is injected by reciprocating valve arrangement operated by flow of the water. The flow is controlled by a maximum flow orifice, a minimum flow orifice and an adjustable valve. The air compressor supplies a surge tank and the air is passed from the surge tank through a pressure regulator to a mixing device where the water and surfactant is mixed with the air to generate the foam.

Abstract: An air/liquid polymeric latex foam coating generator includes a static splash plate mixer for forming a coarse foam coating and a conventional static refining mixer which further refines and homogenizes the coarse foam produced by the static splash plate mixer before delivering a refined foam to application heads or nozzles for application to a workpiece. The static splash plate mixer comprises a housing which is divided into two chambers by a splash plate. A stream of pressurized air and a stream of pressurized polymeric latex coating material are introduced into the upstream chamber where the streams intersect each other, impinge upon the splash plate and are mixed into a coarse foam in the upstream chamber. The foam passes through openings in the splash plate to the downstream chamber where the foam is further refine before being discharged from the static splash plate mixer.

Abstract: The objectives of the present invention are achieved by preparing a foamable composition comprising a viscous liquid and a gas homogeneously dispersed in the liquid. The compositions are prepared by blending a pressurized gas with the viscous liquid in a mixing chamber. In accordance with the present method the flow rate of the pressurized gas into the mixing chamber is controlled as a function of the flow rate of at least one high viscosity liquid into said chamber. The apparatus includes a means for controlling the flow rate of the pressurized gas as a function of either the difference in the feed pressures of said gas and said liquid or a predetermined ratio of the volumes of liquid and gas present in said mixing chamber.

Abstract: Methods and apparatus for producing high quality closed cell foams for use in applications such as coatings, sealant beads, seam filling and gaskets. An in-line single pass static mixing device containing a very large number of individual mixing elements is used to homogeneously disperse a gas throughout a highly viscous liquid polymeric material such as a plastisol, silicone, butyl or urethane based material.

Abstract: An apparatus for mixing and activating polymer which includes the introduction of gas with water and polymer in order to create a variable density type foam which aids in the activation and enhances the efficiency of the polymer. The apparatus of the preferred embodiment provides the introduction of water and polymer into a mixing loop having a premixing manifold containing a static mixer, injecting or sparging gas into the outflow from the static mixer, blending and activating by mechanical agitation the water polymer and gas mixture, partially feeding back into the mixing loop the mixture to provide a desired level of polymer activation which is delivered at a desired rate of flow. This system provides capabilities for selecting the desired level of activation, levels of polymer concentration, levels of overall flow rate as well as controlling the various energy imparting elements of the apparatus.

Abstract: A foam generator is provided for in-line installation within a surface tubing network. The generator has a foaming chamber with a plurality of permeable screens positioned in series along a continuous flowpath through the foaming chamber. The screens are separated from one another by spacers that define the radial boundaries of the flowpath. According to one embodiment, the screens and spacers are mounted in a cartridge that fits into the foaming chamber to maintain proper screen alignment and facilitate removal of the screens from the chamber for maintenance. In an alternate embodiment, the screens and spacers are mounted directly in the chamber. In both embodiments, the screens are aligned orthogonal to the flowpath enabling the generator to produce a properly textured foam from shear-sensitive fluids with relatively little shear degradation.

Abstract: A method for the beneficiation of mineral ores by the flotation method whereby a slurry is introduced under pressure into the top of a first column through a downwardly facing nozzle, and air is entrained into the slurry forming a downwardly moving foam bed in the first column. The foam bed passes from the bottom of the first column into a second column where the froth and liquid separate, the froth carrying the values floating upwardly and over a weir and the liquid being drained with the gangue. The liquid/froth interface level in the second column is kept above the bottom of the first column, and the air flow rate into the top of the first column is controlled to keep the first column substantially full of foam.

Abstract: A filter device and method of filtering components from a surgery plume. The filter device is comprised of a plurality of elements which react with one or more components of a surgery plume, such as that generated during electrocautery or laser surgery. The filter device, particularly in conjunction with a separate particle filter, removes cyanide, formaldehyde, benzene, and particulates, as well as odor-causing species and moisture from the surgery plume.

Abstract: A nozzle for continuously generating a foam is used for the purpose of bathing, cleaning, fire extinguishing, sterilizing or the like. The nozzle includes as essential components a chemical agent liquid mixture preparing unit, a cylindrical holder to be held in by a user's hand, an injection nozzle attached to the foremost end of the holder for ejecting a chemical agent liquid mixture as a spray, a cylindrical sleeve secured to the holder with a diameter larger than that of the holder, air intake ports formed through the cylindrical sleeve, and a screen fixedly secured to the foremost end of the cylindrical sleeve for allowing a mixture of the ejected spray and the introduced air to collide therewith and thereby generate a foam. The distance between the injection nozzle and the screen can be adjusted, and moreover, the flow rate of air to be introduced into the cylindrical sleeve through the intake air ports can be adjusted.

Abstract: A foam-fluid composition for use in foam fracture applications and foam slurry transport comprises a thickening amount of a viscoelastic surfactant composition, a functionally effective amount of a surfactant composition capable of forming a foam, and an aqueous liquid. Foam-fluid formulations are easily prepared, reusable, shear stable, easily pumped and form stable foams over a wide temperature range and exhibit high viscosities even at relatively high temperatures.

Abstract: A foam generator is provided for generating a treatment foam within a pipe, such as a sewer pipe, in need of treatment. The foam generator includes a foam generating head having a first perforated conduit for carrying a fluid such as compressed air and a second perforated conduit surrounding said first conduit for carrying a fluid such as a liquid which contains a foaming agent and a treatment chemical. A wicking material surrounds the first and second conduits in the foam generating head and receives the compressed air and liquid from the conduits and causes the production of a foam. A pressure casing can surround the foam generating head for delivering the foam under increased pressure to coat an inner wall surface of the pipe.

Abstract: A apparatus of atomizing a high solids viscous composition onto a substrate and foaming the composition comprising mixing a coating composition with a gas forming agent under elevated pressure and temperature. The coating composition is airlessly atomized and projected onto a substrate. The gas remains dissolved in the coating after depositing on the substrate which causes the coating to foam after striking the substrate. The apparatus provides a permanent foam coating composition with uniform cell distribution. The apparatus is particularly suitable for foaming polymeric coatings such as plastisols and foods such as peanut butter or chocolate.

Abstract: A method of making a post foaming gel comprising the following steps: A gel base is cycled between first and second cylinders and a heat exchanger. A foaming agent is introduced to the cycled gel base through the heat exchanger while the gel base is being cycled.

Abstract: The adjustable bubble generator comprises a stationary casing having an air introduction aperture and a plurality of bubble discharge holes on the top wall; a movable casing having substantially the same outer configuration as that of the stationary one but adapted to be slidably inserted into the stationary casing; and an extensible distributor conduit contained within the stationary and movable casings so that it can be extended or retracted in response to the sliding movement of said movable casing with respect to the stationary one.

Abstract: A method and apparatus for dispensing a foamable, pressurized solution of a gas and a high viscosity polymeric material in a manner which produces a foamed bead having a hollow core. Initial foaming occurs in a nozzle through which the solution is dispensed to atmosphere, at a core of the bead. Subsequent foaming of of the bead exteriorly of the core occurs outside the nozzle, and results in an extruded, foamed bead of high viscosity polymeric material having a tubular shape and particularly suitable for form-in-place gasket applications.

Abstract: An apparatus for making a post-foaming gel comprising, a first cylinder having a chamber and a slidable piston separating the chamber into a first compartment to receive a gel base and a second compartment, a second cylinder having a chamber and a slidable piston separating the chamber into a first compartment to receive the gel base and a second compartment, a conduit connecting the first compartments of the first and second cylinders, a device for reciprocating the pistons in the first and second cylinders to cycle the gel base through the conduit between the first compartments of the first and second cylinders, and a device for introducing a foaming agent to the gel base while it is being cycled between the cylinders.

Abstract: A foam generating apparatus is disclosed which generates foam from a foamable liquid by pumping the liquid by means of a high pressure pump from a storage tank to a combining device in which the liquid is combined with compressed air. The apparatus is capable of both operation and storage under extremely cold ambient conditions without the components of the apparatus becoming frozen. When the apparatus is not generating the product foam, a foamable liquid is recirculated throughout the apparatus to prevent the components of the apparatus from becoming frozen. The recirculation system is especially useful in preventing the high pressure pump from becoming frozen during storage in cold environments, while also reducing the amount of wear on the pump.

Abstract: An apparatus for continuously charging a liquid reactant with a gas is provided. The gas is dispersed in the reactant through a hollow stirrer in a gassing tank. The quantity of gas introduced per unit time is kept constant.

Abstract: A method of producing a polyurethane foam comprising the steps of dissolving rapidly and substantially completely a non-condensible non-reactive gas in a liquid isocyanate component or a liquid polyol component or both while the isocyanate and polyol components are maintained separate from one another, while controlling the flow of the non-reactive gas to maintain a predetermined dissolved gas to liquid ratio, and while maintaining the component in which the nucleating agent is being dissolved under pressure sufficient to maintain the gas in solution and to hold substantially constant the dissolved gas to liquid ratio and mixing the previously separated isocyanate and polyol components together while reducing the pressure to nucleate the dissolved gas in the isocyanate and polyol components and while impinging liquid streams of the composition together thereby enhancing mixing and permitting the mixture to foam so as to form a fine celled polyurethane foam.

Abstract: The present invention relates to an improved apparatus for the production of a flowable mixture which reacts to form foam from flowable components stored in storage containers, wherein prior to metered introduction into a mixing zone, at least one of the components is charged with a defined quantity of gas, by (i) introducing said one component and gas separately into a gasification chamber equipped with a hollow stirrer, (ii) sucking gas into said component through the hollow shaft of the hollow stirrer, and (iii) stirring the gas into the component, until the desired value is attained, the improvement wherein (a) the component is circulated from the storage container through the gasification chamber and back into the storage container, (b) the gas sucked through the hollow shaft of the hollow stirrer being maintained at pressure at least equal to the pressure prevailing in the storage container, and (c) the component fraction remaining in the storage container is homogenized during those periods in which ga

Abstract: The present invention is directed to an apparatus for introducing gas into one of at least two free-flowing components which are subsequently mixed to provide a foam-forming free-flowing mixture by transferring the component to have gas dispersed therein from a supply container to a gas loading area, loading the component with gas and returning the component to the supply area, wherein the gas used in the gas loading area is obtained from a gas cushion maintained in the supply container and wherein the gas is compressed to a pressure higher than the pressure in the gas loading area before it is dispersed into the free-flowing component.

Abstract: A device for taking milk by creating a vacuum in its container and supplying it already whipped directly to the cup for the preparation of Italian cappuccino coffee in combination with the steam nozzle of an expresso coffee machine. A device of this type comprises a tubular body having an inner conical seat in the vicinity of one end with which the output conical surface of an injector cooperates to form a space, the injector being extended in the form of a rod provided with splash-guard members up to the opposite end of the tubular body for leak-tight connection with the steam nozzle and with the tubular body. An air intake upstream of the splash-guard members and a rubber connection for taking the milk from the container are disposed to communicate with the space while at the downstream end of the conical seat there are disposed two coaxial nozzles forming a space via which the milk is whipped and discharged.

Abstract: The present invention relates to an improved process for the production of a flowable mixture which reacts to form foam from flowable components stored in storage containers, wherein prior to metered introduction into a mixing zone, at least one of the components is charged with a defined quantity of gas, by (i) introducing said one component and gas separately into a gasification chamber equipped with a hollow stirrer, (ii) sucking gas into said component through the hollow shaft of the hollow stirrer, and (iii) stirring the gas into the component, until the desired value is attained, the improvement wherein (a) the component is circulated from the storage container through the gasification chamber and back into the storage container, (b) the gas sucked through the hollow shaft of the hollow stirrer being maintained at a pressure at least equal to the pressure prevailing in the storage container, and (c) the component fraction remaining in the storage container is homogenized during those periods in which ga

Abstract: A bubble generator for producing cellular concrete which comprises an interchangeable housing containing a plurality of particles. The housing is releasably connected to a first and second retaining means at its respective first and second ends for retaining the particles in the housing. The particles contained in the housing can be the same or different in size, substantially spherical or nodular in shape, and about 100 to 6000 in number. The device generates uniform and strong bubbles of frother solution for cellular concrete.

Abstract: An apparatus for making a post-forming gel comprising, a first cylinder having a chamber and a slidable piston separating the chamber into a first compartment to receive a gel base and a second compartment, and a second cylinder having a chamber and a slidable piston separating the chamber into a first compartment to receive the gel base and a second compartment, with the first compartments of the first and second cylinder facing each other. The apparatus has a shaft connecting the pistons of the first and second cylinders, and a conduit connecting the first compartments of the first and second cylinders. The apparatus has a device for reciprocating the pistons in the first and second cylinders to cycle the gel base through the conduit between the first compartments of the first and second cylinders, and a device for introducing a foaming agent to the gel base while it is being cycled between the cylinders.

Abstract: An apparatus for making a post-foaming gel comprising, a first cylinder having a chamber and a slidable piston separating the chamber into a first compartment to receive a gel base and a second compartment, a second cylinder having a chamber and a slidable piston separating the chamber into a first compartment to receive the gel base and a second compartment, a conduit connecting the first compartments of the first and second cylinders, a device for reciprocating the pistons in the first and second cylinders to cycle the gel base through the conduit between the first compartments of the first and second cylinders, and a device for introducing a foaming agent to the gel base while it is being cycled between the cylinders.

Abstract: A fluid mixing apparatus is provided in which pressure plates and collection plates are stacked alternately, with cavities between, the pressure plates each having an annular band of fine flow holes while the collection plates each have one or a small number of comparatively large flow-holes eccentrically disposed in relation to the center of the plate. The cavities between the plates can be provided by depressions formed in both faces of each collection plate. The pressure plates can each advantageously comprise a mesh or screen structure to provide the fine flow-holes.

Abstract: An apparatus for making post-foaming gels comprising, a piston chamber having an outer case defining a chamber, a piston being slidably received in the case and separating the chamber into a first compartment adjacent one end of the case for retaining a gel base, and a second compartment adjacent the other end of the case for retaining a compressed gas, with said piston having a hollow stem extending out of the other end of the case. The apparatus has a device for circulating the gel base through the stem and first compartment, and a device for introducing a foaming agent to the gel base while it is being circulated throught the piston chamber.

Abstract: A method for using a foamed liquid for cleaning and/or inerting a vessel is described which allows for continuous recycling of the foam and its breakout liquid and gas components into regenerated foam which is continously directed back into the vessel.

Abstract: Apparatus and methods are provided for producing a proppant carrying foamed fracturing fluid or the like having very high ratios of proppant material to the liquid phase of the foam, which can be substantially higher than even the theoretical maximum ratio available when the proppant is introduced into a foaming apparatus as a proppant/liquid slurry. This is accomplished by a dry sand foam generation process wherein the sand or other particulate material is introduced into a foam generator apparatus as a dry particulate material in a stream of gas which is subsequently mixed with a second liquid stream.

Abstract: Apparatus for controlling the flow of a foam uses a bellow enclosed in a housing. The bellows is filled with foam under pressure from a foam generator and expands a preselected amount at which point the flow of foam into the bellows is interrupted. Simultaneously with the interrupting of the flow of foam into the bellows, air under pressure is routed into the housing which causes the bellows to collapse forcing the foam out of the bellows. The apparatus is particularly useful in the froth flotation (benefication) of minerals.

Abstract: An apparatus for producing cleaning suds includes a reservoir containing a cleaning solution connected to the outlet of a vacuum cleaner or the like. The apparatus includes a flexible hose connected to the upper portion of the reservoir through which air passes from the vacuum cleaner outlet to a venturi nozzle at the remote end of the hose. An inner supply tube extends along the interior of the flexible hose and connects to the cleaning solution within the reservoir through a pressure reducing ball valve. The outlet of the supply tube is movable toward and away from the venturi to regulate the flow of the cleaning solution. Cleaning solution delivered to the venturi through the supply tube is formed into suds which are expelled onto a surface to be cleaned.

Abstract: A foam generating nozzle construction, and method of use is disclosed, wherein a tubular nozzle body, with an inlet and outlet has turbulence inducing means in the form of contiguous transverse apertured plates preceding air aspirating means. A pressurized mixture of water and foaming agent enters the nozzle and diverges through a first set of apertures in an obstructing plate, then converges through a contiguous plate with a central aperture partially overlying the first set of apertures to create a turbulent spray which then entrains air from aspiration holes to produce a low or medium expansion foam with an enhanced drain time.