Abstract: A device for displaying the exhaustion of a gas filter filled with an adsorbent (3). A toxic gas detector (14) determines the toxic gas content at a sampling site (8) within the adsorbent (3). A reference sampling site (12) is located in the area of a gas inlet point (6) of the gas filter (2). The toxic gas detector is designed such that it determines the toxic gas content alternately at the sampling sites (8, 12), and the exhaustion of the filter is determined by a comparison of the toxic gas content at the sampling site (8) with the toxic gas content at the reference sampling site (12).

Abstract: A fan drive checking system, for an air conditioning system in a clean room having a fan filter unit (FFU), includes a flow sensor for sensing air flow inside a housing of a FFU. The sensor provides a sensor signal indicative of normal and adverse flow conditions in the housing. A control portion in data communication with the sensor outputs a control signal responsive to the sensing signal. An alarm in data communication with the control portion provides a warning when the control signal indicates the adverse flow condition.

Abstract: A fan filter unit has a blower, a motor, a filter and a charge induction sensor installed on the ceiling of a clean room. The charge induction sensor is movable between a drive stopped position at which the sensor can be seen with the naked eye and a normal drive position at which the sensor can not be discriminated from the bottom of the filter. The direction of air passing through the filter and static charges prevailing in the unit dictate the position assumed by the sensor.

Abstract: This invention relates to a filter change indicator that is operable in various orientations of the device incorporating it. For example, the filter change indicator is operable when the device is positioned in either the upright or sideways position. The device incorporating the filter change indicator can be any air moving device which incorporates a cleanable or replaceable filter. The filter change indicator includes a transparent viewing window and a tubulation. The viewing window displays a visible signal when the filter needs changing. The visible signal can be a float retained in the tubulation. The tubulation is a hollow transparent tube which forms an incline plane within the housing. The tubulation includes a first end, a second end and a step. The first end is in fluid communication with an air flow path through the tubulation, and this air flow path is exposed to atmospheric pressure.

Abstract: An exhaust filter for insertion into an exhaust port of a liquid bath vacuum cleaner has an elongated, tubular inlet secured to a lower housing, which lower housing is secured within an upper housing. The upper end of the tubular inlet extends into the upper housing and is provided with a flat top portion and a series of openings between angled vanes so as to direct air flow entering the tubular inlet evenly around the circumference of the angle vanes and through a HEPA filter sealingly secured between the lower and upper housings. Air flows through the HEPA air filter and out slotted openings in opposed ends of the exhaust filter. The flow of air at one end passes by a rotary blade having an indicator element thereon, which indicates the condition of the HEPA filter, and when the exhaust filter must be replaced.

Abstract: An indoor unit of an air-conditioner having a unit body, provided on a rear of a ceiling, having an lower surface portion exposed indoor and an indoor heat exchanger and a blower in its exterior, a decorative panel, structured as the lower surface portion for the unit body, having an inlet port for guiding air in a room to the indoor heat exchanger, a filter fixing portion, structured as a part of the decorative panel, having a filter attached to a position opposite to the inlet port to be detachable, a support portion for supporting the filter fixing portion to be freely rotatable to the decorative panel, and an open/close driving mechanism for driving the filter fixing portion to be freely opened and closed against the decorative panel in a state that the support portion is used as a fulcrum, the mechanism for hanging the filter fixing portion from a ceiling surface when being opened to be moved.

Abstract: A monitoring apparatus for alerting an operator to the need to change a temperature control system filter includes a mechanism for selecting and setting a primary period of filter use to assure replacement before the filter becomes clogged; a mechanism for counting out the selected primary period; a mechanism for activating a signalling device to signal the operator to replace the filter, absent replacement of the filter; a mechanism for sensing replacement of the filter; a mechanism for resetting the mechanism for counting to begin the counting out the selected primary period again upon replacement of the filter; a mechanism for counting out a secondary period measured from the end of the primary period; a mechanism for shutting down the system at the end of the secondary period absent replacement of the filter; and a mechanism for detecting a fire within the building. The apparatus preferably additionally includes a mechanism for shutting down the temperature control system upon detection of a fire.

Abstract: An air purifier, an air filter and a method of manufacturing an air filter for an air purifier are provided. The air purifier includes a base assembly, a filter assembly and a grill. A fan is mounted to the base assembly, and draws air through the filter assembly. The base and filter assemblies include adjoining walls having openings which are substantially smaller in area than the areas of the adjoining walls and area through which air is drawn in through the filter assembly. A resilient gasket having a passage approximately the size of these openings is positioned between the adjoining walls. The filter assembly is drawn towards the base assembly when the fan is operated, thereby enhancing the seal formed by the gasket against the adjoining walls. Unfiltered air is accordingly unlikely to bypass the filter assembly. The air filter is manufactured in an efficient manner through the use of a back plate having oblique end portions.

Abstract: This invention relates to a filter change indicator that is operable in various orientations of the device incorporating it. For example, the filter change indicator is operable when the device is positioned in either the upright or sideways position. The device incorporating the filter change indicator can be any air moving device which incorporates a cleanable or replaceable filter. The filter change indicator includes a transparent viewing window and a tubulation. The viewing window displays a visible signal when the filter needs changing. The visible signal can be a float retained in the tubulation. The tubulation is a hollow transparent tube which forms an incline plane within the housing. The tubulation includes a first end, a second end and a step. The first end is in fluid communication with an air flow path through the tubulation, and this air flow path is exposed to atmospheric pressure.

Abstract: A method is provided for efficiently controlling the operation of a vapor recovery system including a first reaction vessel and first bed of adsorbent, a second reaction vessel and second bed of adsorbent and a vacuum pump for selectively regenerating those beds of adsorbent. The method includes the step of adsorbing vapor from an air-volatile liquid vapor mixture on the first bed of adsorbent in the first reaction vessel, measuring a total amount of the vapor adsorbed by the first bed of adsorbent, comparing the total amount of vapor adsorbed on the first bed of adsorbent to a first predetermined value which is a percentage of the first bed adsorbance capacity and regenerating the first bed of adsorbent and adsorbing the vapor from the air-volatile liquid vapor mixture on the second bed of adsorbent in the second reaction vessel upon reaching the first predetermined value.

Abstract: An air filtering apparatus including motor selectively connected to a power source, a fan driven by the motor and creating an air flow, a replaceable filter element selectively positioned in the air flow path, and an electronic control. The electronic control includes a clogged filter element detector and an indicator and a missing filter element detector. The current drawn by the fan motor is sensed by a current transformer and compared to a predetermined threshold by a comparator in each detector. If the current drawn by the fan motor is less than the clogged filter element predetermined threshold, the clogged filter element detector operates an indicator. If the current drawn by the fan motor is greater than the missing filter element predetermined threshold, the missing filter element detector operates a controller to disconnect the fan motor from the power source.

Abstract: A monitoring apparatus for alerting an operator to the need to change a temperature control system filter includes a mechanism for selecting and setting a primary period of filter use to assure replacement before the filter becomes clogged; a mechanism for counting out the selected primary period; a mechanism for activating a signalling device to signal the operator to replace the filter, absent replacement of the filter; a mechanism for sensing replacement of the filter; and a mechanism for resetting the mechanism for counting to begin the counting out the selected primary period again upon replacement of the filter. The apparatus preferably additionally includes a mechanism for counting out a secondary period measured from the end of the primary period; and a mechanism for shutting down the system at the end of the secondary period absent replacement of the filter.

Abstract: A compact cyclone filter train for the removal of hazardous and radiologi particles from a gaseous fluid medium which permits a small cyclone separator to be used in a very small space envelope due to the arrangement of the filter housing adjacent to the separator with the cyclone separator and the filters mounted on a plate. The entire unit will have a hoist connection at the center of gravity so that the entire unit including the separator, the filters, and the base can be lifted and repositioned as desired.

Abstract: The smoke filtration unit described herein has an internal cylindrical duct for ducting exhaust smoke from an exhaust flue to a shutter pivotally mounted within the cylindrical duct. The shutter can move between at least two positions. The shutter, when located in a first position, directs exhaust smoke to a cylindrical filter. An exhaust fan draws the exhaust smoke through the filter. The residual gas is vented to the atmosphere. The cylindrical filter is mounted on a vibration mount that can vibrate the filter to dislodge particulate matter that collects on the surface of the filter. The dislodged particulate matter falls into an ash collection area. The smoke filtration unit is controlled by a microcontroller that monitors temperature and pressure conditions within the unit. If excessive pressure conditions are detected, the microcontroller energizes the vibration mount to dislodge particulate matter from the filter.

Abstract: A method and apparatus are disclosed for cleaning filter elements, such as filter bags in a plurality of baghouses and for predicting the useful life of such filter elements in individual baghouses. The volumetric flow rate of air from each baghouse is continually calculated using actual impact and static pressure measurements and compared with a flow rate set point. The set point is continually adjusted for density correction based on the actual air stream temperature. The bags are pulsed for cleaning when the flow rate is less than the adjusted set point. Pulsing is then halted when the flow rate reaches or exceeds the adjusted set point. Total daily cleaning times are accumulated over time and graphically displayed to indicate when a critical level is reached indicating that filter bag change out is needed. Each baghouse is monitored in this manner to reflect the unique operating conditions of each baghouse.

Abstract: The electrostatic air cleaning system is mounted in a duct of a residential or commercial heating and cooling system to remove particles from the circulating air. The electrostatic air cleaning system includes an air flow sensor which turns the air cleaner off in response to the lack of air flow through the air duct. An air flow sensor circuit connected to the electrostatic air cleaner includes a thermistor which detects the lack of air flow in the duct and provides a signal in response to lack of airflow. The signal from the sensor causes the power supply to the electrostatic air cleaner to be disconnected when there is insufficient air flow through the air duct. The air flow sensor circuit is configured so that power will continue to be supplied to the electrostatic air cleaner from the power supply when the sensor is disabled for a variety of reasons.

Abstract: A window fan incorporating a filter. The fan has a low, flat profile for fitting in a window while occupying limited viewing area of the window. The fan includes laterally projecting extensions for sealing a gap which might otherwise exist at the right and left sides of the fan. The fan includes a motorized squirrel cage blower for forcing air through a flow path defined within the window fan. The blower is elongated, and oriented with its rotational axis arranged horizontally to enable the low profile. The filter is washable, and is installed by sliding into a holding chamber, and located serially within the air flow path. The window fan has a manually adjustable air deflector for directing discharged air as desired. The electrical circuit conducting power to the motor includes a touch sensitive switch for on-off control, a thermostatic switch for operating the fan when the touch switch is on and a predetermined temperature is detected, a speed selector switch, and an indicating lamp.

Abstract: A moisture absorbing media filter includes a housing into which a moisture absorbing material is placed, an end cap fabricated from a clear plastic fits over the housing, exhalations pass through the end cap into an impermeable tube which terminates at substantially the middle of a bore contained in the moisture absorbing material. A tapered chamber follows the impermeable tube and terminates at the end of the moisture absorbing material, a reduced passage follows a pellet filter and leads to an outlet opening, a dyeing agent is deposited into the tapered chamber, a predetermined amount of low vapor pressure, water soluble liquid is also deposited into the tapered chamber. Exhalations enter the inlet opening and pass through the impermeable tube into the tapered chamber, low vapor pressure, water soluble liquid deposited in the tapered chamber allows moisture in the gas to be absorbed by the moisture absorbing material but not the gas itself.

Abstract: A filter indicator system for indicating when air flow through a filter is restricted includes an indicator mounted in a filter assembly downstream of the filter. The indicator includes a housing having a central space, a side wall, an end wall, an end inlet in the end wall, and a side outlet. A pop-up member is located in the central space and includes a signal portion which extends adjacent the end inlet. A moving device is then used for moving the pop-up member between a non-signalling position where the signal member does not extend noticeably through the end inlet and a signalling position where the signal portion extends noticeably through the end inlet.

Abstract: A regenerative hygroscopic filter having a housing containing an inlet port and an outlet port, and, a hydrophilic filter element positioned within the housing and disposed between the inlet and outlet ports, and operatively arranged to filter solid particulate matter and water when gas passes into the inlet port and through the filter element, and to release water via the inlet port when gas passes from the outlet port through the filter element.

Abstract: A high-efficiency air filtering apparatus for cleaning and circulating air in a closed room is in the shape of a vertical cylinder and includes a semi-cylindrical housing and a semi-cylindrical filtering chamber, both enclosing a centrifugal blower configured to suck filtered air out of the apparatus through the filter and to blow it into the room. The apparatus is characterized by that the filtering chamber contains a closely pleated filter sheet of HEPA-filter which is covered on top and bottom by flat panels and is air-tightly pressed onto the semi-cylindrical housing, thus making the apparatus completely air tight. The filtering chamber is urged onto the contour of the filtering chamber and is releasably fastened to the top and bottom of the housing, permitting replacement of the filter after clogging.

Abstract: A noise maker having a housing with a hole formed on at least one surface of the housing and a weighted member in resilient relationship over the hole. The weighted member is movable between a first position closing the hole to a second position for allowing a desired volume of air to flow through the hole so as to produce an audible sound. The weighted member is slidably mounted on a dowel rod within the housing. A slider plate is provided with a plurality of hole sizes formed thereon. The slider plate is interposed between the hole and the weighted member. The hole is formed on a first planar surface of the housing. The housing has an opening formed on a second planar surface of the housing. The first and second planar surfaces are in parallel relationship. A chamber extends between these surfaces. The surfaces in the chamber are permanently coupled together. The chamber has a rectangular configuration.

Abstract: A gas purifier for impure gas having an end of life detector. The purifier has:A. a housing; andB. an impurity-sorbing material packed within the housing. The impurity-sorbing material has the property of reacting with impurities in the impure gas. This reacting causes expansion of the impurity-sorbing material; andC. an impure gas inlet; andD. a pure gas outlet; andE. a pressure responsive electrical switch within the housing. The position of the switch is responsive to expansion of the impurity-sorbing material; andF. An indicator outside the housing to indicate the position of the switch.

Abstract: A gas purifier for impure gas is provided with a sensor of the end of useful life. The purifier has a housing completely filled with a gas sorbing material. The gas sorbing material is capable of reacting with the impurities contained within the impure gas. This reaction results in an expansion of the gas sorbing material which thereby causes the housing to expand.The purifier also has an impure gas inlet and a purified gas outlet as well as a strain gauge carried by the housing and means for determining the strain on the strain gauge thus determining the end of useful life of the gas sorbing material.

Abstract: A vacuum motor and fan are mounted within a housing, the lower end of which receives a high efficiency particle filter. The bottom of the housing includes a series of projections adapted to be received in corresponding apertures on an upper flange of the filter to prevent replacing the filter with an improper one. The projection/apertures also promote proper seating of the seal between the filter canister and the housing. A separate projection on the filter engages and actuates a lock-out switch carried by the housing to permit the machine to operate only when the filter is of proper size and capacity and it is properly seated on the housing.

Abstract: A concentration of a given gas is detected by a gas sensor when a command signal for turning off the gas sensor is present, the concentration is stored and the gas sensor is turned off. The invention detects the concentration of the given gas by the gas sensor when a command signal for turning on the gas sensor is present and determines a reference value by choosing either the stored concentration or the concentration detected after the gas sensor is turned on whichever is lower at an instant a predetermined interval after the gas sensor is turned on. A blower motor of an air cleaner is controlled in accordance with the difference between the reference value and the concentration detected after the gas sensor is turned on. In a second method, the concentration is stored in a nonvolatile memory just before the air cleaner is turned off. In a third method, a given value may be set as the reference value replacing the stored concentration if the given value is smaller than the stored concentration.

Abstract: An apparatus including a housing secured to a filter web, wherein the housing includes a reciprocating rod directed orthogonally through the housing relative to the filter web, whereupon plugging of the filter web permits the rod to be directed through the housing to effect actuation of a switch therewithin. The rod mounts a magnet to track a plurality of contacts of a switch within the housing to effect actuation of an audible and visual alarm.

Abstract: This invention is a filter assembly to be installed in passenger motor vehicles for the protection of the occupants from pollution originating from either exterior the vehicle and/or interior the vehicle. The assembly is preferably installed in the plenum of the vent which is connected to the cowl plenum chamber of the vehicle's heating-cooling system. The assembly is also preferably equipped with a sensor switch that notifies the drive whenever the filter becomes dirty and must be replaced. The assembly includes a hot fluid heater, such as a hot water heater, which protects the filter from freezing and keeps the filter dry. The assembly prevents pollutants, which are emitted from the exhaust fumes of motor vehicles, as well as odors, hydrocarbons, smoke, soot, dust and allergens-pollen from polluting the motor vehicle interior. By installing the filter assembly in motor vehicles, we can be assured of breathing purer air.

Abstract: In a suction cleaner comprising a housing (10) having an inlet (11), a filter chamber (12) with a filter bag (13), a suction fan (14) with a motor (15), and an outlet passage (17) through which filtered air passes from the suction fan to an outet (16), the motor is provided with a control circuit (20) adapted to be activated by a first pressure switch (21) which is actuated by the underpressure in the filter chamber (12) in order to control the motor power at a predetermined level. According to the invention, the suction cleaner is provided with a second pressure switch (22) which is actuated by the pressure in the outlet (17) and adapted to activate the control circuit (20) when said pressure exceeds a predetermined level.

Abstract: A control circuit for an air cleaner including a gas sensor, an ultraviolet sensor and a control circuit for performing an automatic operation of the air cleaner in response to the detection of outputs of the sensors. A predetermined number of electrical pulses from the ultraviolet sensor are observed by the control circuit during a first predetermined time period after the passage of a second predetermined time period from a point of time when an initial pulse from the ultraviolet sensor has been inputted to the control circuit, the control circuit identifies the predetermined number of the pulses as a drive signal for initiating the operation of the air cleaner.

Abstract: An air cleaning machine to be used in houses, offices and so on utilizes an ultraviolet-ray sensor and a gas sensor jointly to combine the characteristics, so that the operation of the appliance becomes extremely smooth. The appliance operates almost immediately especially when a signal from a light is received. If a cigarette is lighted, for example, indoors, the air cleaning machine operates immediately to clean the air, so that the user may actually feel it. When the gas occurs even under the circumstance where the ultraviolet ray does not reach the light sensor, the normal operation is performed, thus allowing the automatic operation to be effected. Accordingly, clean air is normally provided under the optimum circumstance.

Abstract: In a vacuum cleaner having a disposable dust bag of the kind comprising an attachment plate of cardboard or the like, and a cover adapted to be opened for the replacement of the dust bag, a blocking device is provided which is adapted to prevent closing of the cover when the dust bag is missing. The blocking device includes a slide actuated by a spring to be moved to a first position in which the closing of the cover is prevented, and a toggle-joint mechanism adapted to be actuated by the attachment plate to move the slide to a second position for permitting closing of the cover.

Abstract: A flow rate sensor for use with an air filter channels air flow to energize an audible sound generator upon development of an air pressure differential within the sensor above a settable threshold, which pressure differential results from a reduction in the air flow rate through the air filter due to clogging of the air filter by filtered matter.

Abstract: A laser surgery smoke evacuator system is disposed within a small, thermally and acoustically insulated casing. The system includes a filter, a vacuum pump disposed downstream of the filter, an alternating current motor driven by an AC power source, a DC power supply energized by the AC source, an AC phase controller to vary the motor speed, a capacitor circuit to isolate the phase control from electromotive interference and a filter clog circuit. The DC power supply powers the phase controller and the capacitor and filter clog circuits. The AC phase controller is mounted next to an air intake in the casing for cooling the motor. The motor drives the vacuum pump which evacuates smoke from a laser surgery site, draws such smoke through the filter and exhausts clean air from the casing.

Abstract: This invention is a pollution cleansing system inside a motor vehicle for the protection of the occupants. An "Air Purifier" is built into the vehicle's cowl plenum chamber of the heating-cooling system and in the vehicle's side vents. The "Air Purifier" prevents pollutants, such as exhaust fumes of the motor vehicle, including dust and smoke entering the motor vehicle interior. By installing the "Air Purifier" in motor vehicles we can be assured of breathing purer air.

Abstract: Visual indication of respirator cartridge end-of-service life is accomplished with color indicator means particularly designed for long term shelf life and an adaptability to respond to both water soluble and water insoluble organic vapors.

Abstract: A sensing and indicator system for monitoring multiple electric heating elements connected in three-phase balanced Y circuits in heat reactivatable adsorbent gas fractionators. The system senses a failure induced imbalance, pinpoints the location of the group with the failure and causes a failure indicating alarm to function. The system operates by a sensing circuit including a discharge bulb sensing the failure induced imbalance and causing a conduction of current through the system resulting in the activation of an alarm and the illumination of the gas discharge bulb indicating which of multiple sets of heating elements has failed.

Abstract: The invention disclosed is an indicator for monitoring the capacity of a CO.sub.2 absorbent to absorb CO.sub.2. The indicator is typically used in association with a closed circuit breathing apparatus, including a container for a CO.sub.2 absorbent. The indicator comprises temperature sensing means immersed in the absorbent, a temperature to voltage converter for converting a sensed temperature reading to an electrical voltage signal, temperature trend processing means for processing said electrical voltage signal into a selected electrical output signal characteristic of a temperature trend; and display means for converting said selected electrical output signal to a predetermined visual display indicative of the capacity of the CO.sub.2 absorbent to absorb CO.sub.2.

Abstract: The invention provides a detector for detecting air components, e.g. contaminations, and in particular noxious or poisonous contaminations, which device comprises a housing in which an air pervious carrier containing a first reagent is arranged, this detector being adapted to draw air to be tested through said carrier so as to expose this reagent to the air, this reagent being influenced by the components to be detected, which carrier is to be contacted with a second reagent which, together with the first one, can bring about a color reaction depending on the fact whether the first reagent has been influenced or not.

Abstract: A fill-up indication arrangement for a vacuum cleaner includes a diaphragm adapted to move up and down in response to a pressure build-up in the vacuum cleaner and an indicator disc connected to the diaphragm through a pivotable gear sector and a stop on the indicator disc, which stop engages with the teeth of the gear sector when the indicator disc takes its angular position thus indicating that a filter bag contained in the vacuum cleaner is full and should be replaced.

Abstract: There is provided a full bag indicator which is calibrated by movement of it along the structure it is mounted to, to thereby vary an aperture leading into the full bag indicator.

Abstract: A system for recovering as power the pressure and sensible heat of the gas discharged from the top of a blast furnace by guiding the gas to a dry-type dust collector for the removal of dust while maintaining the gas at the furnace top pressure and introducing the gas into a turbine for expansion. To protect the dry-type dust collector when the gas is run off from the furnace at an abnormally high temperature, a gas channel extending from the furnace to the dust collector is provided with at least one injector, which injects a cooling fluid into the gas in response to a signal from a temperature detecting sensor disposed close to the gas outlet of the dust collector. The sensor which is positioned near the dust collector outlet detects the temperature without the time delay attributable to the deposition of dust. With use of the dry-type dust collector, the gas can be fed to the turbine almost without cooling for the recovery of an increased amount of power.

Abstract: An improved canister for a filter-type respirator having an end-of-service life warning device which is located in a position such that all air flowing through the canister flows through the warning device after the air has flowed through at least about 50 volume percent of the filtering material contained in the respirator.

Abstract: An air flow sensing arrangement is disclosed for use in a vacuum cleaner. A plenum chamber or cavity established by a first wall and a second wall is provided adjacent to a fan inlet with all air from a bag chamber being directed radially inward therethrough toward an aperture in the first wall communicating with the fan inlet. The second wall is provided with openings adjacent to its outer periphery so that air is proportionally directed into the cavity along a plurality of paths. An air distribution chamber is established by the second wall and a secondary filter is supported on the second wall. Air is distributed by the distribution chamber about an entire outer surface of a wall portion of the second wall so as to maintan a consistent proportion of air flow through the openings into the cavity in the event irregular filter clogging occurs. A flow sensing device including a pivoting vane having a magnet thereon is disposed within the cavity so as to be within a path of air flowing through the openings.

Abstract: A fibrous filter mat of which all or a part of the fibers are coated totally or at least in part with a mixture of at least two dye components which are insoluble in one another, one of said components being fat- and/or oil-soluble and of a color which contrasts with that of the fiber blend and/or of the other component, the other component being fat- and/or oil-insoluble. The mat is especially suited for kitchen exhaust hoods since entrapment of fats and oils causes a color change as the oil-soluble dye dissolves and spreads out.

Abstract: A vacuum cleaner has a housing with an inlet which can be closed by a cover. A dust bag can be installed in the housing suspended from a plate which is located inwardly of the cover and has two openings both of which communicate with the interior of the bag. The cover carries a suction nipple which sealingly enters one of the openings when the cover is closed. A connecting nipple is also carried by the cover and sealingly enters the other opening when the cover is closed. The entire connecting nipple, or a diaphragm mounted in the same, moves in direction towards the cover when, in response to increasing filling of the bag and clogging of the filter pores thereof, the pressure in the bag rises to a level higher than the pressure at the other side of the connecting nipple or diaphragm, respectively. This movement is transmitted to an indicator observable from the exterior of the vacuum cleaner and provides an indication of the degree to which the bag is filled.

Abstract: A visually observable means for indicating end of service life of hazardous vapor/gas respirator cartridges or canisters is disclosed. A colorimetric indicator in sheet form is positioned along the inner transparent sidewall of the respirator cartridge or canister.

Abstract: A control system and method for a spray absorber desulphurization system including a SO.sub.2 feedback control loop, a temperature feedback control loop, partial and complete shutdown controls having feed forward sensors.

Abstract: An electrolytic device adapted for mounting on the interior wall of a container housing sorbent chemicals for detection and display of moisture content. A sandwich or tab-type probe includes superhydroscopic MgClO.sub.4 or CaSO.sub.4 particles which resist electrical current flow when dry and have a higher affinity for moisture than the sorbent chemicals in cartridges or filters. Moisture intrusion is drawn to the anhydrous MgClO.sub.4 or CaSO.sub.4 particles changing their ohmic resistance and thereby enabling visual and nondestructive detection of the moisture intrusion into the container or cartridge. The probe is spaced away from the sorbent chemicals avoiding the transfer of mechanical stresses and any additional pressure drop through the sorbents, thereby permitting the device to be used in combination with a wide range of sealed containers and air filters.

Abstract: A vacuum motor and fan are mounted within a housing, the lower end of which receives a high efficiency particle filter. The bottom of the housing includes a series of projections adapted to be received in corresponding apertures on an upper flange of the filter to prevent replacing the filter with an improper one. The projection/apertures also promote proper seating of the seal between the filter canister and the housing. A separate projection on the filter engages and actuates a lock-out switch carried by the housing to permit the machine to operate only when the filter is of proper size and capacity and it is properly seated on the housing.