Abstract: An apparatus includes a housing defining an internal volume and structured to house aftertreatment component for reducing constituents of an exhaust gas. A noise reducing component is disposed within the internal volume and structured to extend around at least a portion of the aftertreatment component.

Abstract: A control circuit of an oxygen concentrator maintains pressure within a compressor of the oxygen concentrator. The control circuit includes a microprocessor that controls functioning of a controller based on two or more of: a user-adjustable flow rate of oxygen delivered by the oxygen concentrator to a user, an ambient temperature, and an ambient pressure. The functioning of the controller further controls the adsorption of various gases by sieve beds of the oxygen concentrator to produce oxygen enriched gas.

Abstract: An electroplating system includes an enclosure with an interior, an anode lead extending through the enclosure and into the interior, and a porous body. The porous body is supported within the interior of the enclosure for coupling an electroplating solution within the interior with a workpiece. A conduit extends through the enclosure and into the interior of the enclosure to provide a flow of nitrogen enriched air to the interior of enclosure for drying and removing oxygen from the electroplating solution.

Abstract: Provided are a non-hydrocarbon gas separation device and the like capable of increasing a discharge pressure of a non-hydrocarbon gas to a downstream side while preventing an increase in size of equipment. In the non-hydrocarbon gas separation device, a first separation module (2a) and a second separation module (2b) connected to each other in series are each configured to separate a non-hydrocarbon from a natural gas through use of a separation membrane (20). The non-hydrocarbon gas having been separated from the natural gas is discharged to each of discharge lines (202) and (204). At this time, a pressure of the first separation module (2a) on a discharge line (202) side is higher than a pressure of the second separation module (2b) on a discharge line (204) or (202) side.

Abstract: A gas-liquid separator with enhanced performance and easy operation, capable of performing gas-liquid separation, such as advanced defoaming or degassing, and with a structural arrangement that facilitates easy CIP cleaning and disassembly cleaning, allowing to meet sanitary specifications. The gas-liquid separator for gas-liquid separation performed by centrifugal force includes an impeller, a suction inlet, a discharge outlet, an exhaust outlet, a separation impeller part, a discharge impeller part, and a vacuum device.

Abstract: A source supplier includes a source reservoir that contains a liquefied source fluid for a supercritical process, a vaporizer that vaporizes the liquefied source fluid into a gaseous source fluid under high pressure, a purifier that removes organic impurities and moistures from the gaseous source fluid and an analyzer connected to the purifier that analyzes an impurity fraction and a moisture fraction in the gaseous source fluid. Moisture and organic impurities are removed from the source fluid to reduce the moisture concentration of the supercritical fluid in the supercritical process.

Abstract: A control device for gas appliances (1) comprises: a manual-control element (12, 22); a circuit arrangement (25a) that includes control elements, electrical-interconnection elements, detection elements for detecting actuation of the manual-control element (12, 22) and supplying corresponding signals to the control elements; and a supporting structure (21), which can be associated in a stationary way with respect to a gas tap, wherein the supporting structure (21) includes at least one first part of stationary structure (40, 41) that defines a housing for at least part of the circuit arrangement (25a), the first part of structure (40, 41) being in particular designed for being housed within a body of a gas appliance. The control elements are designed for counting the time, and the device includes optical warning elements (43?, LG).

Abstract: The air separation unit includes a single adsorption bed downstream of a reversing blower and configured to operate on the principle of vacuum swing adsorption. An optimal ambient air pressure to vacuum pressure ratio within an adsorber vessel downstream of the reversible blower is identified. When the air separation unit is operated at ambient conditions where ambient air pressure is different, such as at higher altitude (or lower altitude) a pressure ratio across the blower when drawing a vacuum on the adsorption bed is maintained for optimal blower power to oxygen production performance. Time for recovery of the adsorption bed can also be modified due to the lower absolute pressure achieved within the adsorption bed when the pressure ratio across the blower is maintained. An ASU is thus provided which is optimized for performance at various different altitudes without requiring modification of equipment within the ASU.

Abstract: A pressure swing adsorption apparatus for treatment of gases is disclosed. It includes a main inlet for receiving a flow of gas and one or more adsorption columns containing adsorption material. The columns are connected by a channel and the channel has an annular recess therein to receive a valve. The valve includes a support member formed from a pair of truncated cones and having slots extending therethrough. The valve also has a tubular membrane that surrounds the support member and is movable, in response to pneumatic pressure applied to the membrane, between a first position in which the membrane does not block the slots thereby allowing the gases to flow and a second position in which the membrane blocks the slots thereby preventing said gases from flowing through the valve.

Abstract: Systems and methods are provided for an air purifier with over pressurization relief, including the following components. A room air inlet is configured to fluidly receive air from a room. A supply duct inlet is configured to fluidly receive air from a forced air system. An air filter and or air purification means is configured to filter/purify air. An outlet is configured to expel filtered/treated air into the room. A bypass damper system has at least one air filtering mode position and a bypass mode position. A pressure control mechanism is configured to automatically allow the bypass damper system to move from at least one air filtering mode position to a bypass mode position when the air received from the supply duct inlet exceeds a bypass threshold. The bypass mode position guides air from the supply duct inlet into the room without requiring passage through the filter and the outlet.

Abstract: A method of removing CO2 from an input gas stream, the method comprising reacting a solid sorbent with the input gas stream to remove CO2 from the input gas stream in a carboniser; reacting the solid sorbent from the carboniser in a calciner to release the CO2 into a substantially pure gas stream; exchanging heat between the carboniser and calciner; and controlling a CO2 partial pressure and temperature in the carboniser and a CO2 partial pressure and temperature in the calciner such that the temperature in the carboniser is higher than the temperature in the calciner for providing heat from the carboniser to the calciner.

Abstract: Method for removing dissolved gases from water to produce boiler feed water in a catalytic steam reforming process where boiler feed water is heated by indirect heat transfer with a reformate stream and/or a combustion product gas stream and the boiler feed water subsequently flash vaporized to form steam and residual liquid water, where the steam formed by flash vaporization strips the dissolved gases from the water.

Abstract: A gas chromatograph-mass spectrometer (GC-MS) system includes a multi-capillary GC column coupled to a mass analyzer through an ionization interface. The ionization interface includes an ionization device and an ion guide configured for receiving a high-capacity gas-sample flow from the GC column and transmitting a compressed ion beam to the mass analyzer. The ion beam may be converging.

Abstract: A method is provided for estimating the degree of saturation (S) of a reversible solid ammonia storage material (3) in a storage unit (1). The storage unit (1) is equipped with a heater (2) to release ammonia and a connected tube (4) for ammonia flow. The initial temperature (TINIT) is measured with a sensor (9) in or around the storage unit (1) before any heating is initiated. Heating is initiated while recording the active time of heating (t) or the amount of energy (Q) released by the heater. The desorption pressure created by solid storage material in the storage unit (1) is measured via a pressure sensor (8) in fluid communication with the storage unit (1). The time (tTARGET), or the heat (QTARGET) where the pressure reaches a certain target pressure (PTARGET) is recorded. The values of the target-pressure time (tTARGET), or the target-pressure heat (QTARGET), and the initial temperature (TINIT) are used to compute an approximate degree of saturation (S).

Abstract: Provided is a novel hydrogen separation membrane formed of a Nb—W—Mo-based alloy. A method for separating hydrogen using the hydrogen separation membrane and hydrogen separation conditions are selected by a particular procedure. A hydrogen separation membrane formed of the Nb—W—Mo-based alloy membrane.

Abstract: One exemplary embodiment can be a process for separating particulate solids from a gas stream. The process can include regenerating a catalyst in a regenerator, separating particulate solids in first and second cyclone stages, passing the gas stream from the second cyclone stage to an external third stage separator, and passing the gas stream from the external third stage separator to a cyclone recirculator to obtain a clean gas stream.

Abstract: A system and System for removing CO2 from an input gas stream. The system comprises a carboniser segment configured such that a solid sorbent reacts therein with the input gas stream to remove CO2 from the input gas stream; a calciner segment configured such that the solid sorbent from the carboniser segment reacts therein to release the CO2 into a substantially pure gas stream; a heat exchanger unit for exchanging heat between the carboniser and calciner segments; a first conditioning unit for controlling a CO2 partial pressure in the carboniser segment; and a second conditioning unit for controlling a CO2 partial pressure in the calciner segment; wherein the first and second conditioning units are configured such that a difference between the CO2 partial pressures in the carboniser and calciner segments respectively is controlled such that heat is provided from the carboniser to the calciner through the heat exchanging unit.

Abstract: Method and apparatus for a membrane separation system, including process and installation for the separation of air by permeation, using two strategically placed heaters for the production of high purity nitrogen, uniquely designed multi-staged pre-filtration system and a novel method of controlling the nitrogen flow and purity. The system comprises in series an air compressor (1), an air cooler (2) cooled by air or liquid, moisture separator (3), mist removing filter (4), primary heat source (5), coalescing filter (8), carbon tower (9), particle filter (10), secondary heat source (11), membrane separator(s) (14), and control valve (19). The system is to provide and maintain superheated air to the membrane separator(s) using strategically located heaters to eliminate condensation of moisture in the carbon tower or membrane separator(s) eliminating the need for a separate compressed air dryer, or the need for insulation of pipes, vessels and the membrane separator(s).

Abstract: The invention relates to a method for controlling the power of a sorption refrigeration system, comprising an adsorber unit, a condenser (C), and an evaporator (E) through which a cooling carrier fluid (KT) flows, with alternating application of the adsorber unit by a valve unit (HV_IN, HV_OUT) operated via a controller, having a circuit process of at least one sorption phase and at least one heat recovery phase, wherein a measurement of a current cooling carrier outlet temperature (Takt) is carried out in the return of the evaporator, a calculation of an averaged cooling carrier outlet temperature (Tgem) is carried out during the first and second sorption phases with a comparison to the current cooling carrier outlet temperature (Takt), and a control signal is trigger upon completion of the sorption phase as a function of the difference between the averaged cooling carrier outlet temperature (Tgem) and the current cooling carrier outlet temperature (Tgem). The invention provides a corresponding device.

Abstract: Information used for creating an adsorption isostere of a substance to be measured in a measuring system (container) is obtained by repeating alternately a first control step of changing temperature or pressure of the measuring system by a fixed amount by adjusting a gas amount supplied to/discharged from the measuring system, and a second control step of changing pressure or temperature of the measuring system by adjusting the gas amount supplied to/discharged from the measuring system until a gas adsorption amount of the substance to be measured becomes the same as before execution of the first control step.

Abstract: A diesel particulate filter system comprising: a temperature sensor on the inlet side of the diesel particulate filter; a temperature sensor on the outlet side of the diesel particulate filter; a pressure sensor on the inlet side of the diesel particulate filter; and a control module in communication with the temperature sensors and the pressure sensor, and the control module is loaded with a look-up table that correlates the amount of soot loaded in the diesel particulate filter to a change in pressure measured by the pressure sensor; wherein the control module Initiates a regeneration cycle when soot loading of the diesel particulate filter achieves a predetermined soot load.

Abstract: An active carbon filter unit for a tank system consists of a housing (13) in which two chambers (31, 32) are formed, carrying an active carbon filling, which form a section of a flow path which at its one end leads via a valve (6) and an air filter (7) into the ambient atmosphere and at its other end leads via a valve (9) and a non-return valve (10) to a connection for producing an underpressure or into the suction region of an internal combustion engine and via a connection (17) into the tank system. The valves (6, 9), the non-return valve (10) and a housing part (27) receiving the electrical connections thereof are part of a uniform control module (15), which is exchangeably inserted into a recess (14) of the housing (13).

Abstract: A system and process for gas homogenization is disclosed. This has application in the areas of generation of gas and its conversion to electricity in downstream applications. The homogenization system minimizes variance in the gas characteristics (composition, flow, pressure, temperature), thereby rendering a steady stream of gas of consistent quality to the downstream machinery. This homogenization system can be adjusted to optimize the output gas stream for specific end-applications, or to optimize the output gas stream for different input feedstocks. This ensures that overall conversion efficiencies are maximized while keeping the process cost-effective. Such a uniform, steady output gas stream has a wide range of applications in the broad areas of generation of electricity (e.g. using internal combustion engines and combustion turbine engines), chemical synthesis (e.g.

Abstract: Systems and processes are provided for gas separation using high-speed induction variable-speed motors to accelerate and decelerate centrifugal compressors suitable for use in pressure swing adsorption (PSA) or vacuum pressure swing adsorption (VPSA) processes.

Abstract: Various embodiments of a gas storage and supply system and its operation processes having pre-selected temperature and pressure limits are disclosed. Various temperature and pressure profiles may be used to supply stored gas to a gas consuming device.

Abstract: A method for regenerating a particulate filter may comprise calculating a soot layer state correction factor based on a rate of regeneration and a rate of particulate loading in the particulate filter and calculating an estimated soot load in the particulate filter based on a pressure drop of an exhaust gas flowing through the particulate filter and the calculated soot layer state correction factor. The method for regenerating the particulate filter may further comprise causing regeneration of the particulate filter when the estimated soot load is greater than or equal to a threshold value.

Abstract: A composite filter media for a vacuum cleaner comprising a first filtration layer comprising a slit film having a plurality of continuous electrostatically-charged polyolefin filaments disposed substantially parallel to each other along their lengths; and a second filtration layer comprising a high-efficiency filtration media selected from wet-laid filter paper, dry-laid filter paper, and nonwoven filter media; wherein said first filtration layer is disposed in series with said second filtration layer, with respect to an air flow direction through said vacuum cleaner, to form a composite.

Abstract: Information used for creating an adsorption isostere of a substance to be measured in a measuring system (container) is obtained by repeating alternately a first control step of changing temperature or pressure of the measuring system by a fixed amount by adjusting a gas amount supplied to/discharged from the measuring system, and a second control step of changing pressure or temperature of the measuring system by adjusting the gas amount supplied to/discharged from the measuring system until a gas adsorption amount of the substance to be measured becomes the same as before execution of the first control step.

Abstract: A system and System for removing CO2 from an input gas stream. The system comprises a carboniser segment configured such that a solid sorbent reacts therein with the input gas stream to remove CO2 from the input gas stream; a calciner segment configured such that the solid sorbent from the carboniser segment reacts therein to release the CO2 into a substantially pure gas stream; a heat exchanger unit for exchanging heat between the carboniser and calciner segments; a first conditioning unit for controlling a CO2 partial pressure in the carboniser segment; and a second conditioning unit for controlling a CO2 partial pressure in the calciner segment; wherein the first and second conditioning units are configured such that a difference between the CO2 partial pressures in the carboniser and calciner segments respectively is controlled such that heat is provided from the carboniser to the calciner through the heat exchanging unit.

Abstract: The present invention describes a system and method for accurately measuring the temperature of a filter element. A temperature transducer, and a communications device are coupled so as to be able to measure and transmit the temperature of a filter element while in use. This system can comprise a single component, integrating both the communication device and the temperature transducer. Alternatively, the system can comprise separate temperature transducer and transmitter components, in communication with one another. In yet another embodiment, a storage element can be added to the system, thereby allowing the device to store a set of temperature values. The use of this device is beneficial to many applications. For example, the ability to read filter temperatures in situ allows improved Sterilization-In-Place (SIP) protocol compliance, since the temperatures of actual filter elements can be directly measured, rather than interpolated as is done currently.

Abstract: A gas remover apparatus suitable for electrical substation high-voltage transformer load tap changers and similar oil-filled equipment removes potentially hazardous and destructive gases from the air-filled volume above the insulating oil bath in which the load tap changer electrical contacts are immersed. The apparatus applies a continuous supply of nitrogen to the load tap changer, and has an orifice to maintain a slight overpressure over an extreme range of climatic conditions. The substantially continuous venting of nitrogen entrains and expels contaminants such as oxygen, water, and potentially explosive breakdown products from the oil, all of which can degrade the performance of the load tap changer.

Abstract: The present invention is a mobile air contaminant control system that includes a filter assembly enclosed by a mobile outer chamber. The filter assembly is tapered to create a large volume air way downstream from the filter assembly that enables more even air flow and filter loading. One or more exhaust fans pull the air through the filter assembly and exhaust it to the exterior of the chamber. The system is functionally attached to an exterior structure having at least one air intake and housing a work piece. As airborne contaminants are generated from the work piece(s), the control system exhausts them from the exterior structure through the filter assembly and into the external environment.

Abstract: Method for drying compressed gas by means of a dryer (7) with pressure vessels (13 and 16), whereby this method comprises the steps of guiding a first part of the gas to a cooler (40) via a regulating valve (43), and of subsequently drying this first part of the gas in the drying pressure vessel (16); and of heating a second part of the gas so as to regenerate the regenerating pressure vessel (13), whereby, when the temperature in the regenerating pressure vessel (13) rises above an upper limit value, the regulating valve (43) will be gradually moved in the direction of the shut position and, when the temperature in the regenerating pressure vessel (13) drops under a predetermined bottom limit, the regulating valve (43) will be gradually moved in the direction of the entirely open position, which adjustment allows to set the compressed gas at a desired temperature.

Abstract: A control system for particulate filters is provided. The control system for a particulate filter includes a clean filter estimating module that estimates a clean pressure based on a first pressure in the particulate filter within a predetermined period of a regeneration event. A soot prediction module estimates a level of soot in the particulate filter based on a comparison of the first pressure and a second pressure in the particulate filter received after the predetermined period.

Abstract: Methods and systems of purifying an acetylene process gas are described. The methods may include the steps of providing an acetylene vessel containing source acetylene mixed with a solvent impurity, and flowing the source acetylene through a purification container that holds a cooled purifying medium, where at least a portion of the solvent impurity in the source acetylene separates as a liquid impurity on the purifying medium. The method may also include removing the liquid from the purification container and flowing a purified acetylene gas from the purification container. The purified acetylene gas has a concentration of the solvent impurity of about 5 vol. % or less, and the separated liquid impurity is removed without interrupting the flow of the acetylene while the purified acetylene gas flows from the purification container to keep the concentration of the solvent impurity substantially constant in the purified acetylene gas.

Abstract: An oxidizing gas purification apparatus (1) for a fuel cell (7) has a compressor (2) that compresses oxidizing gas and sends the oxidizing gas; a cooling apparatus (4), disposed downstream from the compressor (2), that cools the oxidizing gas passing therethrough; an adsorbent unit (5b), disposed downstream from the cooling apparatus (4), that houses an adsorbent (5a) that adsorbs impurities included in the oxidizing gas sent from the cooling apparatus (4) at a prescribed adsorption temperature and releases the adsorbed impurities at a prescribed thermal regeneration temperature that is above the prescribed adsorption temperature by control of the operation of the cooling apparatus (4) to cool the oxidizing gas that has a temperature above the prescribed adsorption temperature and that is sent from the compressor (2).

Abstract: According to some embodiments, a method and a system are provided to receive hydrogen at a first pressure at a first side of a membrane, receive hydrogen at a second pressure from a second side of the membrane, combine the hydrogen received from the second side of the membrane with a purge stream to produce a permeate stream at the second pressure, and separate hydrogen from the permeate stream at a third pressure. The purge stream is associated with a phase transition temperature range.

Abstract: A regeneration method for a particulate filter includes estimating a quantity of particulate matter trapped within the particulate filter, comparing the quantity of particulate matter to a predetermined quantity, heating at least a portion of the particulate filter to a combustion temperature of the particulate matter, and introducing hydrocarbon fuel to the particulate filter. The hydrocarbon fuel facilitates combustion of the particulate matter to regenerate the particulate filter.

Abstract: A multicapillary bundle for use in a gas chromatograph. Each of the capillaries in the bundle is formed using a coating solution containing a stationary phase and a solvent. The capillaries are coated with stationary phase by reducing pressure at a vacuum end of the capillary and creating a moving interface between the coating solution and a film of stationary phase deposited on each of the capillaries. The reducing pressure at the vacuum end of the capillary and the temperature of the capillary are controlled to maintain motion of the moving interface away from the vacuum end of the capillary. Maintained movement of the interface prevents recoating of the stationary phase. A heating wire and capillaries are embedded in a thermally conductive polymer to create a highly responsive method of heating the multicapillary column. An electronic control device controls the feedback temperature of the multicapillary column using the heating wire.

Abstract: Systems and processes are provided for gas separation using high-speed permanent magnet variable-speed motors to accelerate and decelerate centrifugal compressors suitable for use in pressure swing adsorption (PSA) or vacuum pressure swing adsorption (VPSA) processes.

Abstract: The present invention relates to an exhaust emission control apparatus for an internal combustion engine and a process for operating it. The exhaust emission control has a particulate filter for filtering particulate matter from the exhaust of the internal combustion engine, at least one temperature sensor for detecting the temperature of the exhaust, an evaluation unit for evaluating the detected temperature, particularly with regard to a particulate mass burned during a regeneration operation of the particulate filter. The temperature sensor is positioned inside the particulate filter.

Abstract: Data of a barometric pressure that a barometric pressure sensor outputs, and data of an air volume that an air-volume sensor outputs are input into a system control circuit. The system control circuit is provided with a table storing portion. In the table storing portion, a control table is stored. The control table is formed of a plus supplied-voltage value to fan power set by a barometric pressure value and an air-volume value, and a warning instruction. In a case that the warning instruction is selected based on the barometric pressure value and the air-volume value, the system control circuit turns on a warning-use LED so as to inform a user that a filter is clogged.

Abstract: Method of operating an oxygen-permeable mixed conducting membrane having an oxidant feed side, an oxidant feed surface, a permeate side, and a permeate surface, which method comprises controlling the differential strain between the permeate surface and the oxidant feed surface at a value below a selected maximum value by varying the oxygen partial pressure on either or both of the oxidant feed side and the permeate side of the membrane.

Abstract: A flow regulator device for an analytical circuit, characterised by comprising: a fluid restriction (R) of defined characteristics related to the field of application of the analytical circuit, a direct-pressure regulator (2) positioned upstream of said restriction (R), a back pressure regulator (4) positioned downstream of said restriction (R).

Abstract: A process purifies raw biogas created from a renewable source into pipeline grade natural gas and/or D.O.T. specification, or other predetermined specification, gas. The automated scrubbing processed employed and the particular attributes of the system allow the system to function under extreme weather conditions by employing specific tools to control the temperature of the scrubbing water to allow for efficient and effective removal of the carbon dioxide gas. The system also employs specific measures to use recycled scrubbing water, thus eliminating the need for excessive water generally needed to economically employ this type of scrubbing process. The recycled water is continuously de-carbonated to allow the recycled water stream to effectively scrub the raw biogas. Treated gas from the process is then dried, and compressed for introduction into storage tanks or a natural gas pipeline delivery system.

Abstract: An apparatus for reducing a relative humidity of air inside an enclosed space includes a portable outside air heat exchanger unit having a fan operative to create an air stream by drawing outside air from an intake and discharging the air stream through an outlet inside the enclosed space, and a temperature adjusting element located in the air stream. A heating source supplies heat energy to the temperature adjusting element in response to directions from a heat controller. A humidity sensor is operative to sense the relative humidity of the air in a sensing location and to send a humidity signal to the heat controller to change the amount of heat energy supplied to the temperature adjusting element in response to the humidity signal. HEPA filters and ultra-violet lights can shine on the air stream to kill mold spores and the like.

Abstract: Disclosed is a two or three phase separator including a centrifugal separator, a demister (if a three phase separator), and a filter contained within a housing. The filter uses an outside-in flow principle. The filter includes an inner layer or a center core that defines a hollow interior. An outer layer is positioned adjacent and surrounding the inner layer. The outer layer includes a re-enforcement layer, a first particle filter layer, a coalescer layer, and a second particle filter layer. An access cover of the separator includes a cover plug, an actuator cam, a plurality of idler cam plates, and a plurality of mechanisms. The access cover cooperates with an opening and an annular groove in the housing to close off and seal the separator.

Abstract: Method of operating an oxygen-permeable mixed conducting membrane having an oxidant feed side and a permeate side, which method comprises controlling the differential strain between the oxidant feed side and the permeate side by varying either or both of the oxygen partial pressure and the total gas pressure on either or both of the oxidant feed side and the permeate side of the membrane while changing the temperature of the membrane from a first temperature to a second temperature.

Abstract: A particulate trap has a plurality of filters and an air distributor. The air distributor has a first flow member and a second flow member. Each of the first and second flow members have a plurality of openings to allow exhaust flow through the plurality of filters. At least one of the first and second flow members is movable to selectively block exhaust flow to at least one of the plurality of filters at a given time.

Abstract: A method and system for detecting and predicting air filter condition for an air handling system operates by determining a system resistance to air flow. The system resistance is utilized to determine a detection statistic indicative of current filter condition and to predict remaining life of the air filter. The system resistance is determined using models that approximate the expected operation of the air handling system. The approximation is then compared to actual values to obtain a difference. Once the difference between the approximated value exceeds a threshold value, an alarm is initiated that is indicative of system resistance. The remaining air filter life is then determined by using historically gathered data, or by using a known degradation rate of the air filter. Once the remaining life of the air filter is estimated, replacement can be scheduled that would coincide with other maintenance.