Abstract: A package seal inspection system for detecting leaks in a sealed package which includes a box having a plurality of louvers mounted in a front wall, a plurality of strips mounted behind the louvers in the box, means mounted in the box behind the strips for detecting movement of the strips, means for supporting the package in front of the louvers and means for applying pressure to the top of the package whereby when a leak is present, air in the package is forced out and through the louvers to cause one or more of the strips to move and be detected by the detecting means.

Abstract: The device comprises a conveyor for displacing the containers to be tested in translation in relation to a tunnel-shaped fixed enclosure and comprising internally a heating means. This heating means is constituted by a plurality of infrared lamps each of which is protected by a casing having a side transparent to the radiation emitted. An automatic monitoring device checks that each container entering the tunnel leaves it after a given advance of the conveyor, otherwise a safety device is triggered. The device can be used for testing the mechanical strength of pressurized containers of the aerosol can type on a continuous production line.

Abstract: The invention provides an ultrasonic method of inspecting contents (fluid food, for instance) of a package by disposing an ultrasonic transmitter-receiver system on at least one side of the package and evaluating the occurrence or degree of degradation of the contents on the basis of output data from the system. The invention also provides an ultrasonic apparatus for inspecting contents of a package which comprises a shaking device for feeding and shaking the package, an ultrasonic device disposed independently and downstream of the shaking device, and a guide device for feeding the package downstream of the shaking device to the ultrasonic device and further downstream.

Abstract: An apparatus is provided for non-destructively testing for a predetermined minimum release torque of container caps on containers that are sequentially delivered to a torque testing station in the apparatus. The apparatus includes a device for delivering capped containers to the torque testing station; a device for clamping the containers at the torque testing station; a device for grasping the caps of the containers at the torque testing station; a device connected to the cap grasping device for applying a release torque to the container caps; and, a device including a strain gage coupled to the release torque applying device for sensing the level of release torque applied to the caps and providing a signal indicative of such level. Capped containers that pass the test are sequentially passed along for further processing (e.g., packaging and shipping) by the user, and those that fail the test are segregated in a reject area for reprocessing or destruction.

Abstract: A method and apparatus for testing flexible sealed packages of the type wherein the package is at least partially made of a flexible, electrically conductive foil or metallic laminate wherein the capacitance between the flexible conductive foil or metallic laminated of the package and a fixed electrode is measured when the package is subjected externally to a partial vacuum. The apparatus includes an evacuable chamber adapted to support a package under test therewithin so that at least part of the flexible foil or metallic laminate portion of the package lies opposite said fixed electrode and a means for monitoring the capacitance between the electrode and that part of the foil or metallic laminate when the chamber is evacuated.

Abstract: A method of and apparatus for detecting fuel leaks employing color variable indicators. The method comprises the steps of preparing and applying a water soluble non-staining indicator dye to a test surface, observing color changes indicative of hydrocarbon leaks and removing the indicator dye from the test surface. The apparatus comprises in combination means for preparing the indicator dye, means for applying the indicator dye to the test surface and means for removing the dye from the test surface. The indicator dye comprises a major portion of a dry inert mineral carrier from about 0.1 to about 5.0 weight percent of a direct dye which is non-staining on painted surfaces and which does not migrate into or penetrate polyurethane or epoxy resin base painted surfaces, and from 0.1 to about 1.0 weight percent of a surfactant.

Abstract: Method and apparatus for testing hermetic seal integrity of sealed packages and containers, are provided. The method includes placing a sealed test package having at least one semi-flexible surface, within a test chamber. The pressure within the test chamber is changed from a first value to a second value, over the time interval of a test cycle. During the time interval of the test cycle, both the pressure within the test chamber and the displacement of the semi-flexible surface of the test package are continuously measured, and produced therefrom, are a first analog data signal proportional to the pressure within the test chamber, and a second analog data signal proportional to the displacement of the semi-flexible surface of the test package. During the time interval of the test cycle, the first analog data signal is converted into a first discrete data sequence, and the second analog data signal is converted into a second discrete data sequence.

Abstract: Container testing apparatuses and methods for detecting leaks in containers such as at the rims of the container. Preferred apparatus have opposing testing heads with receptacles for receiving ends of a container. Each testing head has two seals. A first or end seal is preferably adapted to seal at the end wall of the container. The second or perimetric seal is expandable against the sidewall of the container. The perimetric seal has an internal expansion chamber which is pressurized to expand the seal into sealing engagement with the container. A differentially pressurized testing fluid is transmitting to a chamber formed between the seals and the container. A detector selectively senses changes in the container associated with the existence of a leak through which the differential pressure of the testing fluid is communicated.

Abstract: A method of testing the integrity of a package seal (14) provided between a container portion (11) and a lid portion (12), includes the steps of: initially reducing the pressure acting on the outer surface of the container portion to cause the lid portion to bow inwardly to a position of substantially maximum concavity while maintaining the ullage volume within the package substantially constant; further reducing the pressure acting on the outer surface of the container portion to distend the container portion for increasing the volume of the ullage space; and sensing for a change in position of the distended container wall.

Abstract: Double seal arrangement with intermediate test gas holding means for leak testing and assuring high hermetic batteries.

Abstract: A method for measuring a curvature of a reflective surface includes the steps of directing a pair of collimated light beams onto a substantially smooth portion of the reflective surface and measuring the separation of the light beam images reflected from the surface as a representation of the curvature of the surface. An apparatus utilizing this method includes a pair of lasers for producing respective collimated light beams, a laser mount arranged to direct the separate light beams from the lasers as substantially parallel light beams onto a substantially smooth portion of a reflective surface being measured to produce respective bright spots on the surface, receiving images of the bright spots onto a diffuse target surface, viewing these bright spot images with a sensor to produce a light intensity pattern encompassing the spots and calculating the separation of the bright spot images from the light intensity pattern as a measure of the curvature of the surface.

Abstract: A pressure testing apparatus has a probe with a piercing tip. The probe sealingly engages a special entry port having a mating pressure-coupling body which establishes a sealing connection with the probe before the tip pierces the package. An adhesive sheet flange extends about the body of the entry port and sealingly secures the body to the package. This eliminates the need for external clamping or holding fixtures. In a preferred embodiment the pressure-coupling body is formed of a semi-rigid material and has a tapered through bore for receiving the probe. A face of the body defines a stop which limits the piercing travel of the probe tip. The probe assembly, in one embodiment has inlet and return ports which accommodate a pressure supply inlet line and a pressure sensing return line, respectively. A single piercing tip enters the packaging, with the inlet port located near to the tip end of the probe, and the return port located at a distal end.

Abstract: The invention relates to a process and an apparatus for monitoring the hermeticity of filled containers closed by sealed-on or welded-on covers, or the like. The air or gas cushion present between the cover and the material with which the container is filled, is heated, and the change caused in the position of the cover, by the resulting increase in the volume of air or gas, is monitored, after which the containers which have been indicated as having missing or faulty covers, are removed.

Abstract: The physical and electrical condition of electrochemical cells of a battery s monitored on a continuous basis so that corrective action can be taken before explosion and/or venting occurs by a method including the steps of:(A) coating the electrically conductive shell of each cell of the battery with a thin non electrically conductive layer,(B) applying a sensor stripe over the non electrically conductive layer so that the sensor stripe does not make electrical contact to the shell of the cell,(C) connecting leads to the sensor and then coating the sensor with a protective layer, and(D) connecting the sensor leads of individual cells of the battery into an electrical series circuit, the remaining leads of the series sensor circuit being connected to an alarm/control network that monitors the conductivity of the series electrical path.

Abstract: The accuracy of measurements made to determine the extent of water vapor trapped upon encapsulation of an electronic device is significantly enhanced by carefully controlling the measurement technique employed. In particular, the encapsulant is generally punctured and the water vapor thus released is monitored. It has been found that to obtain an accurate measurement of the magnitude of the water vapor released, this measurement must be made within 0.1 second of the time of encapsulant punctured and released into a glass system. By using an absorption technique with suitable electronics, this time requirement is fulfilled and significantly more accurate quantitative measurements of entrapped water vapor are obtained.

Abstract: Method and apparatus for determining a vacuum degree of a flexible vacuum package. The vacuum package is sealingly placed within a vacuum chamber and then the vacuum chamber is evacuated to a vacuum degree below the vacuum degree of the vacuum package placed within the vacuum chamber. A start of inflation of the package is detected during the evacuation step and pressure within the vacuum chamber is measured when the start of the inflation of the package is detected.

Abstract: Disclosed is an apparatus and method for testing the integrity and acceptability of the seal of a package before or after it has been sterilized by any chosen conventional process which may include heat sterilization of a sealed package, aseptic packaging or irradiation. Testing is accomplished by subjecting the package or container to a controlled external pressure, preferably a linear actuator, sufficient to create a selected level of internal pressure. Any suitable means may be used to determine the rate of pressure change within a selected time interval. Upper and lower limits of pressure change determine whether the seal is acceptable.

Abstract: For testing filled closed packages of flexible material for leaktightness use is made of an apparatus provided with conveyor means (2) for feeding packages in line and with means for applying pressure to the packages. The last-mentioned means consist of two pressure belts (4, 5) disposed a short distance apart. In the gap (6) between the pressure belts (4, 5) is situated a pivoting arm (8) or a shoe (20) having a pressure chamber (21), whereby it can be determined whether the portion of the package lying in the gap between the pressure belts is taut. This apparatus is in particular suitable for testing bags having two curved surfaces which are joined together by three or four sealing seams.

Abstract: A temporal variation in a fluid pressure of a fixed value applied to an article under inspection, or in the differential pressure between it and a fluid pressure applied to a comparison tank, is measured, and the measured value is compared with a reference value, thereby judging whether the airtightness of the article under inspection is good. Of the measured pressure or differential pressure data, data on the inspected articles judged non-defective are stored, by a predetermined number, in accordance with individual temperature differences between them and the comparison tank, or temperature differences between them a reference temperature, and a mean value of the stored data is calculated for each temperature difference. This mean value is used as a correction value for correcting, for each temperature difference, the measured pressure or differential pressure data on articles subsequently inspected.

Abstract: Pressure variation detecting type leakage inspection equipment which applies a fixed fluid pressure to an article to be inspected and judges whether the article is non-defective or defective, depending upon whether a change in the fluid pressure or in the differential pressure between the article under inspection and a comparison tank is within a prescribed value, data on pressure values or differential pressure values by respective measurement which are within a proper value range are stored in succession, the stored data are averaged to obtain a correction value, and data by each measurement is corrected by the correction value, thereby automatically correcting an error which varies owing to various factors. Thus a proper leakage inspection can be achieved.

Abstract: A method for testing electronic assemblies for resistivity to fluorocarbon solvent permeation. After attaching electronic components on host boards, sample assemblies are selected for testing. Fluorocarbon solvent is added to a container suitably sized to allow complete immersion of the samples. Fluorescent dye is added to the solvent and the solvent dye solution heated to the boiling point. Samples are immersed in the solution and initial time noted. The samples are withdrawn after a predetermined time interval, dried and wiped clean to remove excess solvent/dye from the outside of the components. The electronic assemblies are disassembled and illuminated by ultraviolet light. If dye is observed in an area thought to have been sealed, fluorocarbon solvent permeation is proven.

Abstract: This invention relates to measuring the pressure within a vacuum package prising a flexible, gas-tight film. The package is placed within a bell jar in which a vacuum is generated, and the pressure variation is measured as function of the time.

Abstract: Apparatus for testing for leaks in a flexible package containing loosely packaged product and some air includes a first set of gravitational probes at a first measuring station for applying a load to the package and obtaining a first measure of the thickness of the package under this load, a second set of gravitational probes at a second measuring station for applying a corresponding load to the package in a corresponding position and direction with respect to the package and obtaining a second measure of the thickness of the package under the second load and means for comparing the first and second measures of thickness and for indicating the presence of a leak when the second measure is substantially less than the first.

Abstract: A device for monitoring environmental exposure includes an element whose electrical properties change, in a predetermined way, in response to the environmental exposure. The element may be part of a tuned circuit or of a shield for a tuned circuit. In either case, when the tuned circuit is interrogated, preferably by an r.f. or microwave signal, it emits a signal whose intensity depends on the electrical properties of the element. Thus, an incremental environmental exposure can be measured by a change in the signal intensity. The device is particularly useful for monitoring the condition of perishable materials, because it can be located with the perishable inside a packaging material during both storage and interrogation.

Abstract: The packaging system for a sterile hydrocephalus shunt provides access to the valves of the shunt for air testing of the opening and closing pressures of the valves without compromising the sterility of the shunt. The packaging system comprises two nested plastic packs positioned around the shunt with access to the valves of the shunt being provided by an air feedthrough connector assembly which includes a bacteriostatic filter to maintain the contents of the packaging system sterile against contamination by the air used in the pressure testing of the valves. The bacteriostatic filter is impervious to bacterial contaminants but is pervious to air or gaseous sterilizing agents which may be passed therethrough.

Abstract: An apparatus for pressure testing a can body. The apparatus includes a housing having a pivotable cover and an empty can with the lid attached is placed in a cradle in the housing. As the cover is moved to the closed position, a hollow needle, operably connected to the cover, is automatically inserted through the wall of the can body. On locking of the cover in the closed position, an electric circuit can be established to introduce gas under pressure through the needle into the can body. A readout of the pressure required to bulge the can body is given, thereby indicating whether the can body meets manufacturing specifications.

Abstract: A process and apparatus for testing the degree of vacuum in an evacuated vial. For testing the vacuum, a vial is located at a source of high voltage radio frequency power and the power is applied to the vial. A momentary intense flash of light is applied to the vial to cause ionization of the gas within the vial and the ionization current of the ionized gas within the vial is then sensed and a representation of the value of the ionization current is generated. The representation of the ionized current is compared with a minimum acceptable current value which is indicative of a predetermined minimum allowable vacuum within the vial. The vial is rejected if the measured ionization current is less than the minimum acceptable current value. In one embodiment, the apparatus includes a single station for testing evacuated vials, one at a time. In another embodiment of the apparatus, a plurality of vials are conveyed in a carousel through a series of testing stations.

Abstract: Apparatus for positioning a number of nondestructive dud detectors above a conveyor includes side support members to which a rotatable threaded positioning bar is mounted. The positioning bar includes a number of serially placed threaded positioning segments. The dud detectors are supported by the positioning bar through individual dud detector supports. Each dud detector support includes a threaded block which engages the threaded positioning bar. The threaded positioning segments have threads with different pitches. Rotation of the positioning bar cause the dud detectors to move axially along the positioning bar, and thus transversely over the conveyor belt, at unequal rates. The thread spacing or pitch for each threaded positioning segment is chosen so that the separation between adjacent dud detectors changes while keeping the dud detectors equally spaced.

Abstract: A sealed container having a test port with a membrane which is pervious to gas and impervious to liquid may be tested by connecting a pressure device such as a vacuum pump or pressure pump to the test port and creating a pressure differential between the container side of the membrane and the pump side of the membrane, allowing the pressure differential to equalize through the membrane and monitoring the equalized pressure to detect whether or not the equalized pressure changes, which utilmately allows the observer to determine whether the sealed container has any leaks. If the pressure equalization time is substantially zero, the membrane and/or membrane seal is defective. In the event a leak is determined, the inside of the radio device may be pressurized to a selected pressure, by use of a pressure pump or the like, and then immersed in a liquid such as water. The location of the leak may then be detected by observing the emanation of air bubbles from that portion of the device in which the leak exists.

Abstract: Tungsten halogen lamps require a fill pressure of several atmospheres. To verify the fill pressure at the time of manufacture the pressure is indirectly measured by first measuring the speed of sound within the lamp. A shock wave is produced within the lamp by rapidly heating a lamp filament or producing an arc between two adjacent filaments and measuring the time required for the shock wave to sequentially disturb two spaced light beams passing through the lamp. The speed of sound is determined from the measured time and the pressure is calculated from the speed of sound.

Abstract: This invention relates to a method of and an apparatus for checking sealed containers for pinholes in a vacuum which containers have enclosed therein a vaporizable material, such as a glucose injection solution, distilled water for injection, milk or oil, or a sublimable substance, such as naphthalene (hereinafter referred to collectively as a "vaporizable substance"). With this invention, the vaporizable substance adhering to the sealed container and remaining in a checking chamber is vaporized first by a vaporizing suction means communicating with the checking chamber, and the vaporized substance is cooled and collected by a cooling heat exchanger to eliminate before checking the disturbances due to the vaporizable substance and to thereby assure accurate detection of pinholes.

Abstract: A method of and an apparatus for testing the internal pressure of a sealed container carried on a conveyor belt by striking the container with an electromagnetic pulse thereby causing its wall to vibrate, and to check the internal pressure of the sealed container based upon the frequency of the vibratory sound produced by the sealed container. The vibratory sound is converted to an electrical signal by an electroacoustic transducer and is returned to a container striking device in a feedback path thereby to strike repetitively the sealed container with the same frequency of the vibratory sound. The repetitive striking produces continuously without damping a vibratory sound at a frequency commensurate with the natural frequency of vibration of the container. The testing of the internal pressure of the sealed container can be carried out in a stable manner with increased accuracy. A reject system is responsive to the vibratory frequency to permit passage of or to remove the container from the conveyor belt.

Abstract: The invention discloses a monitoring device for monitoring vacuum pressure of an electrical device employing an evacuated envelope. The invention provide, particularly, a pressure responsive monitoring device which comprises an electric field generating device of vacuum type, an electric field detector means including a light source for generating light, an electric field detector detecting change of the electric field of the electric field generator due to the change of vacuum pressure inside the envelope and controlling the light depending upon the change of the electric field, and photoelectric converter for converting the light controlled by the electric field detector to an electric signal which is employed to monitor the vacuum pressure of the envelope.

Abstract: A nondestructive method for inspecting internal pressures of sealed containers wherein a magnetic impulsive force is impinged upon a metallic surface of the container and the resulting vibration of the metallic surface is detected. The detected signal is applied to a plurality of band-pass filters from which the fundamental and harmonics are extracted. The two highest level signals extracted from the band-pass filters, designated the fundamental and a harmonic, are selected, which signals are analyzed by comparison to predetermined values for level and frequency and for their ratio of their levels with respect to one another. A judgment as to the integrity of the sealed container may be made based upon the deviation from the aforesaid predetermined values.

Abstract: A method and apparatus are described for automatically checking envelopes for objects which would interere with an automatic postal mail sorting operation. The envelopes are moved between inflated rollers and changes in the roller pressures caused by objectionable objects in the envelopes are detected to control an envelope diversion gate.

Abstract: A gimbal-type anvil for apparatus for testing in the integrity of a sealed container closure assembly. These assemblies generally comprise a container, a resilient sealing element mounted in the discharge opening in the container and a cup-like cap engaging over the stopper and seating it in place over the discharge opening in the container. The apparatus includes a force applicator for applying an external force to the cap in a direction to further compress the resilient stopper and a microscope to detect initial displacement of the cap relative to the container when the externally applied force exceeds the residual static force in the stopper. The gimbal-type anvil is operatively associated with the force applicator and consists of a housing and at least a pair of annular ring members pivotally connected to the housing about axes transverse to the longitudinal axis of the container closure assembly.

Abstract: The invention relates to a method and apparatus for checking the internal pressure of a filled lamp bulb. According to the invention, a filled bulb to be checked is inserted into a gas tight chamber; the chamber is then sealed and pressurized. The lamp envelope is broken by means in the chamber. Chamber pressure is measured before and after breaking the envelope.

Abstract: A smoke generator is adapted to be used with other apparatus for testing the peripheral seal integrity of a package. The smoke generator heats a fuel within a chamber and then aspirates smoke into a conduit through which fluid is flowing. The apparatus includes additional conduits operatively arranged to selectively flush the chamber of ash and other accumulated particulate material.

Abstract: A method for measuring the amount of a gas, such as carbon dioxide, dissolved in a liquid in a sealed thin-walled container without piercing the container or breaking the seal of the container. This is accomplished by deforming the thin-walled container by exerting a known force thereon, measuring the resulting deflection of the container, and measuring the ambient temperature of the liquid. By reference to a pre-calibrated chart, one can then find the amount of gas dissolved in the liquid at the known temperature and calculated pressure.

Abstract: A method, apparatus and system for determining the integrity of a container sealed by means of a closure comprising a resilient sealing element and a cup-like cap having a top and a depending skirt compressing the resilient sealing element over the discharge opening in the container. The invention consists of verifying seal integrity by applying an external force to the cap and measuring the force required to effect initial movement thereof to overcome the residual static force in the resilient sealing element and by comparing the measured force which is essentially equal to the residual static force in the resilient sealing element to a predetermined standard known to provide an acceptable seal. It is known that when the force between the crimped edge of the cap and the container is zero which occurs upon initial displacement of the cap relative to the container, the externally applied force is essentially equal to the residual static force in the resilient sealing element.

Abstract: An internal pressure inspecting method and system for determining the degree of unevenness of the surface of an elastic cover of each of one or more hermetically sealed containers, the unevenness being produced according to the internal pressure. The distance from a fixed position exterior of the hermetically sealed container to said cover surface is determined by measuring the change in inductance utilizing the action of electromagnetic induction, at a plurality of points i.e. the center and peripheral portions thereof. A value is derived by calculation of the difference between a mean value of both measured values at any one point in the peripheral portion and at the position on the diametric line which is in symmetrical relation therewith with the center of the container cover as the center of symmetry, and the measured value at the center of the container cover. The internal pressure of said hermetically sealed container is determined from this value.

Abstract: A method, apparatus and system for testing the integrity of a container sealed by means of a closure comprising a resilient sealing element and a cup-like cap having a top and a depending skirt compressing the sealing element over the discharge opening in the container. The invention consists in measuring the change in thickness of the resilient sealing element resulting from compression of the sealing element on the container and comparing the change in thickness or a value determined therefrom to a predetermined standard known to indicate sufficient compression to provide an acceptable seal. Resilient sealing element thickness is measured by apparatus including a sensing head having an anvil engageable with the closure mounted on an actuator member of a dial indicator. A face of the anvil engages the top of the cap along a circular line adjacent of the corner radius at its juncture to the top of the cap.

Abstract: A respirator, comprises, a housing having a wall with a sealable opening which is advantageously located in a cover of the housing. A chemical cartridge is disposed in the housing and it has a material capable of generating oxygen upon being started. A breathing tube is connected into the cartridge along with a breathing bag so that a person's respiratory gases may be directed into the cartridge to the bag and then back through the material of the cartridge which also advantageously retains the CO.sub.2 and enriches the respiratory gas with oxygen. A first starter is associated with the cartridge for starting the material so that it generates oxygen and a second control element is disposed in the container adjacent the sealable wall and it has a starting material therein which may be actuated to generate oxygen so as to provide an indication of whether the oxygen-generating material is operating properly and can perform its function.

Abstract: The test apparatus detects pressure changes in a vessel containing a volume of a contaminated industrial liquid and a volume of gas. The apparatus includes a detector having a housing defining a chamber. A pressure transducer having a flexible, pressure-transmitting wall is mounted in the chamber. A passageway fluidly communicates between a port in the housing and the transducer. In one embodiment a needle housing is removably coupled to the port. A hollow needle is adapted to pierce a stopper in the vessel. The vessel remains continuously sealed during and after the pressure test. Pressure changes in the gas of the vessel are transmitted through the needle and the passageway to the transducer. The transducer converts such pressure changes into corresponding electric signals which are indicative of the density of organisms in the liquid contained in the vessel.

Abstract: In the connection and encapsulation of substrates such as cables by covering members such as heat-recoverable sleeves, typically provided with adhesive or mastic linings, the formation upon heating of a desired hermetic seal between the substrate and the covering member is checked by using a device which can detect the excess air pressure which, once the hermetic seal has been made, builds up within a space between the covering member and the substrate. Preferably this is done by means of a probe which passes between the covering member and the substrate into said space and which is connected to a pressure sensitive device such as a balloon or a manometer. After use, the probe, which is preferably made from a plastics material such as nylon, can be fused or deformed to ensure that the hermetic seal remains intact.

Abstract: A method of and a system for checking sealed containers for pinholes with contents enclosed therein by placing a sealed container between first and second electrodes, impressing voltage across the first electrode and second electrodes to generate two discharge current flows on the container and between the first electrode and second electrode respectively, detecting the discharge currents individually and converting the difference between the detected values to a detection signal value.

Abstract: The formation of a hermetic seal in an assembly resulting from the connection or encapsulation of one or more substrates such as cables by one or more dimensionally-recoverable covering members such as heat-recoverable sleeves is checked by detecting the increase in air pressure which occurs during heating of the assembly once a hermetic seal has been made. To this end, a covering member is provided with an aperture which communicates with a detection device such as a balloon or a manometer and with a space within the assembly in which there is a build up of air pressure.

Abstract: A method and apparatus are provided for inspecting vacuum-packed containers. The invention comprises automatically subjecting each container to be inspected to a predetermined force so as to cause each container to emit a click as a result of relative displacement of the container and its liquid contents, and determining whether the container has adequate vacuum by measuring the time interval between application of the predetermined force and the occurrence of the click. In a modification of the invention the pressure determenation is made by generating a signal having an amplitude that varies according to the intensity of the click.

Abstract: An apparatus for detecting defects in empty containers, such as dents in cans, is disclosed. The containers are magnetically struck, causing them to ring at their natural frequencies. A microphone senses this resonance; a bandpass filter filters out the known frequencies generated by an acceptable container. The energy associated with other frequencies is examined to detect defects in the containers. A circuit for reducing the effects of background acoustic noise and a circuit for sensing the amount of energy imparted to the container when it is struck are also disclosed.