Abstract: The present invention provides automated systems for performing electrostatic discharge (ESD) device efficacy monitoring and recording the results for an ESD auditing program. Systems of the present invention comprise at least one ESD device monitoring unit. A communication system allows the monitoring unit to communicate with a central computer which collects, stores and allows the manipulation of the test data. Systems of the present invention are therefore useful in testing the ESD devices, documenting their performance, and controlling access to particular work areas based on testing results.

Abstract: Disclosed are a method and an apparatus for detecting a defect in a dielectric film. The dielectric film is electrified in an electrolyte solution containing a metal in such a manner the dielectric film is charged negative, thereby the metal is deposited on the dielectric film at a position corresponding to the defect. The detecting method has a first deposition step for forming a first metal deposit on the dielectric film in an annular form surrounding the position corresponding to the defect; and a second deposition step for forming a second metal deposit located on the position corresponding to the defect, on the dielectric film. The detecting apparatus has a vessel for accommodating the electrolyte solution; a first electrode for electrifying the dielectric film and a second electrode; and an electric power source for controlably applying a voltage to electrifying between the first electrode and the second electrode in which a value and a direction of the applied voltage is variable.

Abstract: An apparatus and method for detecting a breach in an electrically insulating surface of an electrically conductive power system enclosure within which a number of series connected energy storing devices are disposed. The energy storing devices disposed in the enclosure are connected to a series power connection. A detector is coupled to the series connection and detects a change of state in a test signal derived from the series connected energy storing devices. The detector detects a breach in the insulating layer of the enclosure by detecting a state change in the test signal from a nominal state to a non-nominal state. A voltage detector detects a state change of the test signals from a nominal state, represented by a voltage of a selected end energy storing device, to a non-nominal state, represented by a voltage that substantially exceeds the voltage of the selected opposing end energy storing device.

Abstract: An apparatus for monitoring the status of the insulation on the wire in a winding in a device comprises a surrogate sample of insulating material having a thickness and properties selected to fail before the failure of the insulation on the wires in the winding, and a detector for detecting and indicating failure of the sample of insulating material. A method of monitoring the status of the insulation on the winding in a dynamoelectric device includes associating a surrogate sample of insulating material with the winding, monitoring the surrogate sample, and providing an alarm when the surrogate sample fails, which is predictive of the failure of the insulation on the winding wire.

Abstract: A method of initiating and monitoring partial discharges in an insulating medium is disclosed. Apparatus for performing the method is also disclosed. A relatively low frequency time varying exciting waveform is applied to a sample of an insulating medium. A trigger pulse of short duration is superimposed on the exciting waveform to initiate partial discharge activity in the sample. The apparatus includes a trigger pulse generator with a synchronizing circuit which provides a pre trigger signal for an oscilloscope, allowing the resultant partial discharge activity to be monitored.

Abstract: An apparatus for detecting leaks in a fluid-filled device used to treat a patient's tissue includes an catheter having an expandable device defining a fluid reservoir about the distal end of the catheter. An internal electrode is in electrical contact with a conductive fluid within the fluid reservoir. A grounding electrode is outside of the fluid reservoir, in electrical contact with the patient's tissue. Voltage is supplied to the internal electrode and the grounding electrode. Where a leak occurs in the expandable device, conductive fluid will contact the patient's tissue, thus creating an electrical current path between the internal electrode and the grounding electrode. This so-called "leak current" is used to generate a leak alarm signal.

Abstract: A safety compliance test instrument includes circuitry for performing insulation resistance and ground circuit tests such as a ground bond test, as well as high voltage AC and DC dielectric withstand or hipot tests. A micro-processor based controller provides control signals to a common power circuit, and accepts input of test parameters for all four tests through an integrated user interface including a keypad and menu display.

Abstract: The present invention provides automated systems for performing electrostatic discharge (ESD) device efficacy monitoring and recording the results for an ESD auditing program. Systems of the present invention comprise at least one ESD device monitoring unit. A communication system allows the monitoring unit to communicate with a central computer which collects, stores and allows the manipulation of the test data. Systems of the present invention are therefore useful in testing the ESD devices, documenting their performance, and controlling access to particular work areas based on testing results.

Abstract: A system and method for detecting leakage of a part, includes a controller for generating a start command, a voltage generating circuit for generating at least one high voltage pulse signal in response to the start command, at least one testing station including first and second probes for placing a non-conductive part therebetween and for applying the at least one high voltage pulse signal to the non-conductive part, and an inductive detector detecting current from one of the first and second probes. The inductive detector generates a detection signal in response to the detection and transmits it to the controller. The controller compares the detection signal with a reference signal and determines any presence of leaks in the non-conductive parts based on the comparison result.

Abstract: A method of inspecting a crack in a ceramic substrate that is not exposed on the surface. The method can detect all cracks and make objective judgement possible by expressing the inspection result as numerical data. Conductors are disposed on both faces of a ceramic substrate, wherein one of the conductors is a conductive liquid; the insulation resistance value or an electric property dependent on the insulation resistance is measured with the conductive liquid or other conductors electrically connected to the conductive liquid which are used as electrodes.

Abstract: A method of nondestructive insulation testing is disclosed which comprises the steps of: (a) placing an electric device, having a core and at least one winding provided on the core, in a reduced atmospheric pressure; (b) insulating the laminated core from the ground; (c) supplying a voltage signal having a first surge waveform to the winding; and detecting a glow discharge which may result from step (c) to detect an insulation condition of the winding, wherein the reduced atmospheric pressure ranges from 65 to 75 Torr and the voltage signal is applied in the first direction of the winding and then, is applied in the second, opposite, direction of the winding.

Abstract: A leak-testable, fluid-impervious membrane is formed as a laminate of a conductive mesh scrim between upper and lower insulative polymeric resin layers. The scrim is preferably a screen formed of a metallic wire, such as aluminum. The polymeric resin is preferably a thermoplastic, such as HDPE, PVC, or polypropylene. The membrane, when installed as a liner for a liquid receptacle or a roof, has an exposed surface on the upper insulative layer. When so installed, the membrane is testable for pinhole openings by an electrical leak survey method, in which an electrical potential is applied between the scrim and a conductive probe. The probe is passed over the exposed surface, so that the electrical potential creates an electric spark between the probe and the scrim at the location of a pinhole opening. An RF signal is generated in response to the spark, and an alarm is actuated in response to the RF signal.

Abstract: The porosity and integrity of a nonconductive material is determined using electron beams and electronic instrumentation. The electric corona discharge from holes in the nonconductive material is detected and analyzed in order to determine the presence of viral and sub-viral sized voids or holes, as well as other material anomalies such as blisters and bubbles.

Abstract: Proposed is a device for testing the porosity of dielectric foil, particularly rubber products, such as condoms (2) with a cover holder over which the rubber product is placed, and of one or more outer electrodes (5), whereby the cover holder (1) and the outer electrodes (5) are connected to a source of voltage and an electrical gauge, whereby the outer electrodes (5) are in the form of points and the outer electrodes (5) and the cover holder (1) are relatively moveable toward one another so that the skin of the rubber product can gradually be scanned by the outer electrodes (5), and the gauge measures the flow of current in each electrode and by this measurement corresponds to the electrode in a reference measurement for the state in which there is an absence of material without the application of a rubber product, thereby showing a defect.

Abstract: A load insulator 2, for interposition into a loaded line, comprises a plurality of mechanical links 4 connected together to form a chain, and an electrical insulator 8 arranged between a pair of adjacent interlocked links 10,12 in the form of an insert of insulative material to electrically isolate the links 10,12 of the pair from each other. A load sensing device may be provided for sensing the strain on the mechanical link. A measuring device 24 for measuring the resistance of the insulator 8 is provided to check the electrical condition of the load insulator, whilst a recording and indicating device allows for recording of electrical strikes and provide a lifetime expiry indicator.

Abstract: A sheet such as a geomembrane consisting essentially of an extruded in situ blend of two copolymers of ethylene and one or more alpha-olefins having 3 to 8 carbon atoms, said blend having a flow index in the range of about 3 to about 100 grams per 10 minutes; a melt flow ratio in the range of about 50 to about 200; a density in the range of 0.905 to 0.943 gram per cubic centimeter; an Mw/Mn ratio in the range of about 10 to about 50; and a weight average molecular weight in the range of about 180,000 to about 465,000.

Abstract: Series arcs in an ac circuit are discriminated from other phenomenon by analyzing the timing between pulses in a second derivative of the current signal. A first timer starts timing upon detection of a first pulse in the second derivative of current signal. Time out of the first timer starts a second timer which times a second interval or window during which a series arcing fault will generate a second pulse of opposite polarity to the first pulse. Detection of the first pulse followed by a second pulse of opposite polarity during the window sets a flip-flop to record the event. When a predetermined number of events are counted by a counter within a given time-period set by a third timer, an output signal indicating an arcing fault is generated. If the second pulse is generated before the window opens, or a third pulse occurs during the window, the flip-flop cannot be set so that other events such as the switching of a dimmer do not generate a false output signal.

Abstract: A wet/dry hot stick tester designed to provide a dry test of a hot stick by applying a voltage equivalent to 100 KV/ft to the hot stick, and to provide a wet test of a hot stick by applying a voltage equivalent to 75 KV/ft thereto. Output electrodes are positioned along a reading aperture provided in a housing of the hot stick tester, in which a hot stick being tested is positioned. A two tap transformer has a first input tap for providing a first voltage equivalent to 100 KV/ft to a hot stick positioned in the reading aperture during a dry test thereof, and has a second input tap for providing a second voltage equivalent to 75 KV/ft to a hot stick during a wet test thereof. An ammeter measures the leakage current through the hot stick during an applied voltage. A wet/dry switch switches the two tap transformer between the first and second input taps.

Abstract: A fault detecting circuit for use with an electromagnetic acoustic transducer having an electrostatic shield and a wear surface for determining when the wear surface for contacting test surfaces has developed holes.

Abstract: Methods are provided for detecting and locating leaks in liners used as barriers in the construction of landfills, surface impoundments, water reservoirs, tanks, and the like. Electrodes are placed in the ground around the periphery of the facility, in the leak detection zone located between two liners if present, and/or within the containment facility. Electrical resistivity data is collected using these electrodes. This data is used to map the electrical resistivity distribution beneath the containment liner between two liners in a double-lined facility. In an alternative embodiment, an electrode placed within the lined facility is driven to an electrical potential with respect to another electrode placed at a distance from the lined facility (mise-a-la-masse). Voltage differences are then measured between various combinations of additional electrodes placed in the soil on the periphery of the facility, the leak detection zone, or within the facility.

Abstract: A test instrument for testing magnet wire which is provided which tests, collects and permits analyzing the effect of temperature, frequency, voltage and rise time associated with magnet wire use, and more particularly, the effects of those variables on the insulation of the wire, so as to evaluate the magnet wire performance and inverter controlled dynamoelectric machine applications.

Abstract: An apparatus for detecting the presence, location, and extent of the moise in a roof using metallic time-domain reflectomerry (TDR) includes an electrical pulses, a transmission line embedded within the roof and connected with the pulse generator, and a signal analyzer which interprets the electrical pulses transmitted along the transmission line. When the transmission line is exposed to moisture, the dielectric constant of the transmission line changes, thereby causing a portion of the energy of the transmitted pulse to be reflected back toward the source and a portion to pass through to the end of transmission line. The distance from the source and the length of the dielectric discontinuity are determined by analyzing the round-trip travel time of the reflected pulse.

Abstract: Portable apparatus for inducing an alternating electrical gradient into an impounded liquid media and including, directionally sensitive, sensing apparatus for monitoring gradients established in the liquid to detect leaks at a liquid impermeable membrane. A conductive electrode floated on the liquid directs an amplified square wave signal into the liquid at a 5 to 15 hertz frequency relative to a ground reference established outside the membrane. First and second recessed sensors in a portable, hollow tubular probe are manipulated within the liquid. A portable signal processor monitors a changing signal between the sensors as the probe is moved in the liquid. The sensed and source signals are snychronously sampled, integrated, subtracted in a positive correlation arrangement, and amplified to reject common mode signals within the liquid.

Abstract: A method for monitoring the condition of electrical-motor-driven devices. The method is achieved by monitoring electrical variables associated with the functioning of an operating motor, applying these electrical variables to a three phase equivalent circuit and determining non-symmetrical faults in the operating motor based upon symmetrical components analysis techniques.

Abstract: A high voltage differential is applied across two separated electrodes by a oltage supply. Between these electrodes is located a sample of the solid propellant or other energetic material. The voltage differential across the electrodes generates a spark of measurable voltage, current and time duration in the sample in order to foretell at what energy level sustained ignition of the sample occurs. This spark is measured by a voltage monitor which, upon reaching a predetermined level, sends a signal to a short-circuiting network. The short-circuiting network, after a predetermined time delay, shorts the electrical path across the electrodes thereby removing the voltage differential across the sample and ending the ignition test. An operator is then able to determine visually whether or not the spark of known voltage, current and time duration has created sustained ignition of the sample material.

Abstract: A method and apparatus for detecting the possibility of transfer of material through a protective barrier between a worker and an external object and warning the worker of that possibility is provided. In one embodiment, an electronic leak alarm module is electrically connected to the worker and to the external object. In another embodiment, the module is connected to the worker and a conductive layer on or within the protective barrier.

Abstract: An impoundment leak detection, location, and containment system comprises an impermeable grid having a plurality of leak detection modules positioned below the impoundment. A tunnel is located adjacent the impermeable grid, and a plurality of conduits provide fluid communication between each of the leak detection modules and the tunnel. Fluid leaking from the impoundment accumulates in the leak detection module directly below the leak and flows through the associated conduit where it is detected by a fluid sensor. The location of the leak is determined based on the known location of the leak detection module accumulating fluid.

Abstract: A device for detection of the presence of organic solvents, and a process for the fabrication of the device. This device is particularly useful as a device for the detection and localization of organic solvent leaks, and more particularly to the detection and control of liquid hydrocarbon leaks. In a preferred embodiment the device comprises the combination of a time domain reflectometer and a cable comprised of a composite material constituted of a solvent soluble or swellable thermoplastic matrix containing conductive particles in such a proportion that the whole composite becomes a conductor. Contact with the solvent to be detected causes the matrix to dissolve or swell, which brings about a change in the conductivity of the cable which can be detected by the reflectometer.

Abstract: The portable live line tool tester of the present invention allows high voltage to be applied to discrete segments of a live-line tool. If the tool has become conductive due to damage or contamination, a leakage meter will detect the flow of current. The tool can then be tested in increments to locate the damaged section. The invention further includes electrical safely interlock circuitry so that the tester is rendered inoperable unless it is correctly rigged and safety shielding is in place. The tester can be folded into an easily portable unit, making it unnecessary to ship tools to a laboratory for testing.

Abstract: Procedures and apparatuses for determining the integrity of a geophysical barrier are provided. In particular, an electropotential gradient is established across the barrier in an attempt to drive ionic species through the barrier. The resulting ionic transport results in a current which can be measured between the electrodes, and which can be correlated to the integrity of the barrier. The location of a leak in the barrier can be determined by the use of an electromagnetic sensor which detects an anomaly in the flux field associated with the current.

Abstract: A method for detecting a leakage position in an impervious sheet, which comprises disposing a first and a second electrode units on an upper side and a lower side of the impervious sheet, respectively, the first electrode unit intersecting with the second electrode unit; short-circuiting all of electrodes in the first electrode unit; selecting a plurality of electrode sets one set after another set in the second electrode unit, each set comprising three electrodes adjacent to each other; supplying an AC voltage from an AC power source across a central one of each electrode set and the short circuited electrodes of the first electrode unit; measuring a potential difference between the other electrodes in the each electrode set to produce a measured voltage signal; and phase-detecting the measured voltage signal with a signal synchronized with the AC voltage from the AC power source to produce a detected signal, a series of the detected signals produced one after another changing in polarity due to a damage exi

Abstract: A method and apparatus is provided for monitoring and locating the presence of fluids leaking from a containment vessel. A multiplicity of probes having conductive affinity are strategically oriented adjacent the containment vessel and periodic surveillance is made relying on conductivity of the sub-surface media within which the probes have been placed, such that disturbances in the conductivity correlate with migration of the leaking fluid. The method and apparatus may be utilized to detect migration of salinated fluids into a region where previously less salination existed. The probes can be oriented adjacent a surface and yet determine a conductivity of the sub-surface media at a plurality of different pseudo-points having varying depths. The presence, location and extent of a leak can thus be monitored.

Abstract: This method and apparatus detects the potential for corrosion of pipes fabricated out of conductive material embedded in non-conductive material, due to contact between a conductive medium foreign to the pipe and the conductive material embedded within the pipe wall. The electric potential between the foreign medium and the pipe conductive material is determined. The stability of the potential is then ascertained. If the potential does not vary beyond a predetermined range over a period of time, the potential is deemed stable and is indicative of contact between the foreign medium and the conductive material within the pipe, fostering corrosion. An unstable voltage indicates lack of electrical contact.

Abstract: A system for indicating fault condition on operator's electrostatic discharge protection equipment includes for an operator wearing ESD protection equipment comprising: a conductive wrist-strap in electrical contact with the operator's body, and an electrical wiring to a local ground, a portable system to alert the operator when a problem (cut or poor electrical connection) occurs with wiring to the ground, or when an electrical field reaches a predetermined value at the operator's wrist.In one embodiment, the invention also includes a device for memorizing that an ESD event has occurred.

Abstract: The primary charge roller evaluator is a device to determine an accurate measurement of conductivity or leakage current of primary charge roller, from its steel shaft to outer coating. This measurement is based on the impedance of the roller, that is the in-phase resistance and the capacitive reactance of the roller. This measurement allows the user to evaluate the quality of the primary charge roller. This evaluation is then used to predict the performance of primary charge roller. Accurate conductivity or leakage currents are determined by totally enclosing the primary charge roller in conductive holders and applying a pre-measured pressure on roller for maximum contact. Humidity compensator adjusts for changes in humidity and has non-linear scale to adjust for patented characteristics of rollers.

Abstract: An impoundment leak detection, location, and containment system comprises an impermeable grid having a plurality of leak detection modules positioned below the impoundment. A tunnel is located adjacent the impermeable grid, and a plurality of conduits provide fluid communication between each of the leak detection modules and the tunnel. Fluid leaking from the impoundment accumulates in the leak detection module directly below the leak and flows through the associated conduit where it is detected by a fluid sensor. The location of the leak is determined based on the known location of the leak detection module accumulating fluid.

Abstract: To determine the stabilized surface insulation resistance (SIR) of a printed circuit board substrate, a test printed circuit board is provided which has desirable clean surface conditions. This surface bears a predetermined circuit board test pattern and has a known SIR characteristic resulting in a known stabilized SIR. The test board is then subjected to a soldering step which is performed in the same in-line production with commercial boards. After the soldering step, the SIR characteristic of the soldered test board is determined for a time period sufficient for a comparison with the SIR characteristic of the clean test board to enable the stabilized SIR of the soldered test board to be determined.

Abstract: A method for detecting an insulative condition of a protection layer of a substrate includes the steps of contacting an area of a surface of a protection layer to be detected with a liquid, and checking the electrical conduction between the liquid and a detection electrode which is electrically connected with an electrical element at an area on which the protection layer is not provided.

Abstract: A method and apparatus are described for detecting defects in a condom, protective glove or other similar product during manufacture. The product to be tested is situated on an electrically conductive mandrel, the shape of the mandrel corresponding to the shape of the product. Ions of air are generated and driven toward the mandrel. The flow of ions of air into the mandrel through any holes or tears in the product is detected by measuring the constant current flow through the mandrel. Thickness variations in the product are detected by measuring the duration of the transient current flow through the mandrel.

Abstract: A workstation mat used to monitor radio frequency, electromagnetic field induced currents flowing through the body of a person standing on the workstation mat. The workstation mat includes an upper and lower conductive plate residing in parallel planes. The upper plate is superposed in spaced apart relation over the lower plate. The mat also includes an electronic circuit coupled to the conductive plates. The electronic circuit senses the induced current flowing through a person's body and sounds an alarm to warn the worker when the induced body current meets or exceeds a predetermined current threshold. The threshold setting is variable and preset by the user. The workstation mat has a reset button switch mounted on one lateral side and contains connectors for a remote alarm and a remote reset switch.

Abstract: A method and apparatus for detecting the possibility of transfer of material through a protective barrier between a worker and an external object and warning the worker of that possibility is provided. In one embodiment, an electronic leak alarm module is electrically connected to the worker and to the external object. In another embodiment, the module is connected to the worker and a conductive layer on or within the protective barrier.

Abstract: Electric bus bar insulating coatings are calibrated to withstand long term outdoor exposure without failure. Manufacturing samples of the coating material are evaluated at the coating manufacturing site prior to shipment to the bus bar manufacturer. Bus bar samples coated with the material are suspended within a heated water bath and subjected to several hundred volt-amperes. The thickness of the coating is predetermined to provide accurate qualifying data for each coating sample within a reasonable time frame. Coating compositions that qualify are then applied to electric bus bar conductors by the bus bar manufacturer.

Abstract: A fluid contained in a vessel of multi-layer wall construction can intrude, because of damage or wear, through the inner containment layer and signal a problem with the life expectancy or safety of the vessel. By providing vessel walls having alternating layers of conductive material and non-conductive material, and by providing electrical connections for effecting circuitry to an instrument for measuring electrical properties across the inner containment layer, then intrusion of fluid into or through the inner wall can be detected by the instrument. For a conductive fluid, the inner layer of the vessel wall should be non-conductive and the layer covering that inner layer should be conductive. For a non-conductive fluid, the inner layer of the vessel wall should be conductive, and the layer covering that inner layer should be a non-conductive which is covered by another conductive layer. In many instances, it is preferred that the electrical property measured is the change in resistance, on the megohm scale.

Abstract: A method and apparatus for monitoring and locating the presence of fluids beyond a containment vessel. A multiplicity of plates having conductive affinity are strategically oriented adjacent the area of liquid storage and periodic surveillance relying on conductivity of the substrate within which the electrodes have been placed are made such that disturbances in the conductivity correlates with migration of fluid being contained. The method and apparatus may be utilized to detect migration of salinated fluids into a region where previously less salination existed.

Abstract: Portable and disposable apparatus for leak testing surgical and/or examination gloves which may be worn on the body of the user to permit convenient detection of glove leaks during diagnostic procedures. In one embodiment there is provided an electrolyte-containing pouch worn on the body of the user and into which gloved hands may be inserted for evaluation. A leak in a glove permits the electrolyte to penetrate the glove and contact the skin of the wearer to close an electrical circuit and trigger an alarm.

Abstract: The processing circuit of the insulation monitor comprises a microprocessor receiving on a first input a signal representative of the DC component, or the component of preset frequency different from the frequency of the mains system to be monitored, of the voltage applied to the insulation monitor terminals. The microprocessor receives on a second input a signal obtained by making the difference between a measured voltage representative of said voltage component and a preset threshold value and by multiplying this difference by a multiplication coefficient. When the measured voltage is greater than the threshold value, the microprocessor uses the signal applied to the second input so as to improve the precision in the higher voltage range.

Abstract: A power apparatus has a network formed by a plurality of interconnected components being, e.g., one or more high voltage conductors in a casing of a metal filled with an insulating gas. Detectors are provided which detect electromagnetic waves, which are generated if there is a fault. The electromagnetic waves are analyzed to detect the location of the fault. The analysis may make use of attenuation coefficients corresponding to each component of the network to extrapolate between detectors on either side of the fault and/or to compare with predetermined wave strengths. A map of the network may be stored in a suitable memory to assist in the calculation of the fault location, and the memory may also store the attenuation coefficients themselves. The location of the fault may then be displayed by a suitable display, to give the time variation of the fault.

Abstract: An apparatus for detecting a defect in an insulator formed therein with an axially extending hollow section; having a hold section 2 for holding the insulator, a first electrode 3 inserted in the hollow section 1a of the insulator 1, and a second electrode provided outside of the insulator 1. An electric discharge structure 10 produces an electric discharge between the first and second electrodes 3, 5, a path recognizes 11, 12, 13 for recognizes whether the electric discharge passes through a predetermined path, and a discriminating structure 14 for discriminates whether the insulator 1 is satisfactory, in accordance with a signal from the path recognizes.

Abstract: Investigation apparatus for investigating the distribution of electric charge (2) within an insulator (1) comprises: a function generator (7) suitable for generating a time-varying electrical voltage v, an amplifier (8) suitable for amplifying the voltage from the function generator, the voltage V amplified in this way being applied to the terminals of electrodes (3,4) on either side of the insulator, apparatus (9) suitable for creating sudden deformations that propagate within the insulator, a delay circuit (10) synchronized with the function generator and suitable for triggering the apparatus for creating deformations at a recurrence frequency f.sub.

Abstract: A multilayered coextruded geomembrane system utilized in a variety of applications including, but not limited to, landfills for the disposal of wastes, surface impoundments or ponds, heap leach pads for mining or methane barriers for building and floating covers reservoirs. The geomembrane consists of three or more polymeric layers with outside layers consisting of high density polyethylene at least 0.930 g/cm.sup.3 and a very low density polyethylene inner core layer less than or equal to 0.920 g/cm.sup.3. The melt index of the very low and high density polyethylene is less than 2.0 and 1.0, respectively. Each outside layer of high density polyethylene is 10 to 40% of the total geomembrane thickness. The very low density polyethylene inner core layer is 20 to 80% of the total geomembrane thickness.