Abstract: A method and apparatus for detecting soot and/or water concentrations in diesel engine oil having a dielectric constant may include a device for measuring a change in the dielectric constant at a first frequency, a device for measuring a change in the dielectric constant at a second frequency and a processor configured to calculate at least one of a percentage of soot content and a percentage of water content as a function of the measured changes in the dielectric constant at the first and second frequencies. The first frequency may be within approximately the ultrasonic and sub-AM frequency bands and the second frequency may be within approximately the microwave frequency band.

Abstract: An impedance spectroscopy technique and system for detecting in real time engine coolant contamination in lubricant. A probe is disposed in the lubricant and the probe excited with an a.c. voltage frequency sweep over a selected frequency range. The current and current phase angle are measured at selected frequency intervals and the reactance and resistance computed and plotted at each frequency internal as Nyquist plots. The Nyquist minimum is determined at various lubricant temperatures and a database compiled. The probe is then excited in-situ and current measurements taken for a selected frequency lower than the Nyquist minimum to insure measurement of electrode surfaces characteristics. The reactance and resistance are then computed and the angle ? of change (slope) of reactance with respect to resistance computed. The value of ? is then compared with values of contamination concentration ? versus ? in a database, and the value of ? determined by interpolation.

Abstract: A method and apparatus for measuring a predetermined parameter, by providing a displaceable sensor on a mounting member such that the displaceable sensor changes in location, form or length with respect to the mounting member in accordance with the predetermined parameter. A cyclically-repeating energy wave is transmitted to or through the displaceable sensor, and a predetermined fiducial point in the received cyclically-repeating energy wave is detected and used for continuously changing the frequency of the transmitted cyclically-repeating energy wave such that the number of waves received is a whole integer. The change in frequency is used to produce a measurement of the predetermined parameter. Several embodiments are described wherein the displaceable sensor is a deformable membrane, an end wall of a bellows, a spring-mounted member, a displaceable plunger, and a bar changing its length in accordance with the parameter to be measured.

Abstract: A database is compiled of values of the frequency fNM corresponding to the minimum reactance Z?MIN (Nyquist minimum) versus temperature TL over a selected range of temperatures for a probe immersed in a sample of the fluid to be monitored and excited by an a.c. voltage and the frequency swept over a range to cover both bulk fluid and electrode interface impedance characteristics. The probe is then excited in situ and the temperature measured. The Nyquist minimum is then determined from the database and the current measured on the low frequency (interfacial) side of the Nyquist minimum. The angle ? of the rate of change of resistance Z? with respect to resistance Z? and magnitude of the impedance ZS is then determined from the current measurement; and, the fluid condition ? determined from a previously compiled database of values of ?, ZS and ?.

Abstract: The present invention relates to an apparatus and method for measuring a particulate characteristic of a particulate-containing fluid, in particular for monitoring the particulate content of lubricating or hydraulic fluids in a mechanical system in order to diagnose component failure.

Abstract: A system for determining a quality of a fluid includes an impedance cell immersed in the fluid and impedance instrumentation that communicates with the impedance cell. A controller measures a first impedance of the fluid using an electrical signal at a first frequency, measures a second impedance of the fluid using an electrical signal at a second frequency and measures a third impedance of the fluid using an electrical signal at a third frequency. The controller determines a permittivity and a resistivity of the fluid based on the first, second and third impedances. The quality of the fluid is evaluated based on the permittivity and the resistivity.

Abstract: A method by which contaminant (soot) content in Diesel engine oil is determined using electrical conductivity measurements of the Diesel oil at a high frequency, or by which contaminant (soot and/or water and/or anitfreeze) content is determined using the ratio of electrical conductivity measurements of the Diesel oil at a high frequency to the electrical conductivity measurements of the Diesel oil at a low frequency. Both the conductivity ratio and the high frequency conductivity are essentially independent of the brand of oil. High frequency is defined to be above 2 MHz whereas low frequency is defined to be D.C. to about 1 kHz.

Abstract: A method and apparatus for detecting the concentration of soot particles in engine oil. A microwave signal having a varying frequency is applied to a transmission line having a probe tip exposed to the engine oil. A voltage is read at a stationary detection point along the length of the transmission line for each applied frequency. The applied frequency when the probe voltage is equal to a null voltage of a standing wave within the transmission line is compared to a reference frequency determined when the probe voltage is equal to a null voltage for a known concentration of soot particles. The concentration is calculated based upon the result of the comparison. Preferably, a reference probe receives the same input signal. A known relationship between the reference probe and the transmission line is then used to eliminate temperature effects on the applied frequency.

Abstract: Soot content in Diesel engine lubrication oil is determined using electrical resistance measurements of the oil at high frequency. A sensor in the form of a capacitor is immersed in the oil, wherein the oil serves as a dielectric between the plates. The capacitance and resistance between the plates change as a function of engine oil condition. An inductor is placed in series with the sensor, and high frequencies are sweeped over a range to find resonance where the capacitive and inductive reactances cancel. At this frequency, the resistance of the oil is measured and the condition of the oil thereby determined.

Abstract: A method for determining quality and condition of a highly resistive fluid in transportation and industrial equipment. The method uses apparatus that applies a multitude of oscillating voltage signals at determined frequencies and offsets to electrodes immersed in the fluid and quantifies fluid response to the signals. The method monitors response of the fluid to a preferred three fixed electrical signals applied by the apparatus, a high and a medium frequency signal with zero offset voltage and a low frequency signal with an offset voltage. For apparatus or applications where the monitored fluid is not controlled to constant temperature, the method includes correcting the temperature sensitive fluid responses for temperature variations for the fluid quality and condition determination. The method can also include determining when essentially complete fluid exchanges are made to the equipment without need for additional input.

Abstract: A method and a device for detecting a deterioration of vehicle oil are disclosed in which the end point of the oil service life can be detected with higher accuracy, while at the same time detecting the progress of the oil condition in the vicinity of the end point of the oil service life. The acidity or basicity of the vehicle oil is measured using a pH sensor (11) generating an output in responding to the degree of the acidity or basicity. The deterioration of the vehicle oil can be detected based on the fact that with the increase in vehicle mileage, a line approximating the output of the pH sensor (11) with respect to the vehicle mileage has a tendency to change from a first inclination to a second inclination larger than the first inclination and then from the second inclination to a third inclination smaller than the second inclination.

Abstract: An oil quality measurement device for an oil circuit (1), which includes an oil condition sensor (2) and an analysis circuit (3). The oil condition sensor (2) is constructed as a capacitive or impedance spectroscopic sensor (4) and attached to the filter element (14) in such a way that, when the filter element (14) is replaced, the oil condition sensor (2) is also automatically replaced.

Abstract: A tubular probe having annularly spaced electrodes is immersed in ATF and sequentially excited with an alternating voltage at a relatively high and low frequency. The current is measured at both frequencies and the difference in impedance computed; and, the differential impedance is corrected for temperature and the corresponding value of one of TAN per ASTM D-669, Delta Oxidation per ASTME-168 (?OX) and HPDSC induction time per ASTM D-5483 (MIN) determined from a lookup table of values of TAN, ?OX and MIN versus impedance differential for known fluid conditions. The remaining useful life (RUL) may then be computed from determined present value of TAN, ?OX or MIN. When the temperature corrected impedance difference ?ZTC reaches 6.5×105 Ohms, the ATF is considered to have reached the end of its useful life.

Abstract: A sensor for detecting changes in the dielectric constant of a liquid is described. The sensor has two electrodes immersed in the liquid with dielectric surfaces substantially parallel with each other, and a ramp disposed on a support between the electrodes. The ramp intersects the surfaces at obtuse and acute angles respectively and provides a surface disposed at an angle relative to an electric field extending between the two electrodes, thereby reducing parasitic effects of the sensed dielectric content of the liquid. Slots in the electrode adjacent the lower end of the ramp reduce the strength of the field proximate to the ramp and thereby further reduce the parasitic effects.

Abstract: A probe having a pair of electrodes is excited with a low A.C. voltage at a relatively high and relatively low frequency and the difference in current measured. The difference dZ between bulk fluid and interfacial impedance is computed from the current difference. The rate of change ?dZ of the impedance difference is determined over a time interval and a physiochemical parameter (X) determined when ?dZ is positive from lubricant with known amounts of constituents selected from the group consisting of (a) Phosphorus, Oxygen and Carbon (P—O—C); (b) Phosphorous and double bond Sulphur (P?S); (c) Zincdialkyldithiophosphate (ZDDP); and (d) the Total Base Number TBN by measuring CaCO3 (CO3), from a table of the selected parameter X versus dZ in a first region of the table and determining RUL from a table of RUL versus parameter X (X1). The value of the selected parameter X when ?dz is negative is determined from a second region of the table of X versus dZ.

Abstract: A sensor (40) includes a single capacitor (42) that operates in two different modes to obtain capacitance and conductance information when a mixture flows between the electrodes (44, 46) of the capacitor. The inventive sensor is particularly well-suited for making methanol content determinations within a mixture used to provide hydrogen to supply a fuel cell. Two different oscillators (180, 182) are selectively used to obtain the conductance and capacitance information. In a disclosed embodiment, a capacitor includes an outer electrode (44) that is received around an inner electrode (46) such that there is a spacing between the electrodes through which the mixture flows. The mixture acts as a dielectric of the capacitor allowing the conductance and capacitance measurements to be made. The example sensor includes a temperature sensor (76) conveniently supported within the inner electrode (46).

Abstract: An engine oil deterioration detection apparatus 1 includes a sensing capacitor CS formed of paired electrodes dipped into engine oil whose deterioration is to be detected, the engine oil deterioration detection apparatus detecting deterioration of the engine oil on the basis of a change in electrostatic capacitance of the sensing capacitor CS. A measurement signal generation circuit 10 generates a measurement signal (6) to be supplied to the sensing capacitor CS in order to measure the electrostatic capacitance of the sensing capacitor CS. A detection signal output circuit 30 outputs a detection signal (10) on the basis of a response wave signal (7) produced from the sensing capacitor CS in response to supply of the measurement signal (6) thereto, the detection signal reflecting the electrostatic capacitance of the sensing capacitor CS.

Abstract: A system for determining a quality of a fluid includes an impedance cell immersed in the fluid and impedance instrumentation that communicates with the impedance cell. A controller measures a first impedance of the fluid using an electrical signal at a first frequency, measures a second impedance of the fluid using an electrical signal at a second frequency and measures a third impedance of the fluid using an electrical signal at a third frequency. The controller determines a permittivity and a resistivity of the fluid based on the first, second and third impedances. The quality of the fluid is evaluated based on the permittivity and the resistivity.

Abstract: A method for detecting extraneous matter in a fluid including the steps of applying an energy source to electrodes located in a fluid, measuring real and imaginary electrical impedance values across the electrodes for a plurality of different frequencies of alternating energy and identifying at least one characteristic of an extraneous matter in the fluid.

Abstract: The present invention relates to a process and device for the monitoring of fats and oils in the preparation of food, which provide for the exchange of oil or fat in a timely manner, before they have become harmful for human consumption. The proposed process for measurement distinguishes itself by the fact that the measurement is already taking place during the temperature adaptation of the sensor, whereby a measurement can take place which is particularly fast and thus suitable for use in practice. Along with this, the device is formed in such a manner that disturbances of the measurement can be largely eliminated.

Abstract: A sensor for detecting changes in the dielectric constant of a liquid is described. The sensor has two electrodes immersed in the liquid with dielectric surfaces substantially parallel with each other, and a ramp disposed on a support between the electrodes. The ramp intersects the surfaces at obtuse and acute angles respectively and provides a surface disposed at an angle relative to an electric field extending between the two electrodes, thereby reducing parasitic effects of the sensed dielectric content of the liquid. Slots in the electrode adjacent the lower end of the ramp reduce the strength of the field proximate to the ramp and thereby further reduce the parasitic effects.

Abstract: A method and apparatus for measuring the water content of a liquid, including a method step for electrically measuring the property of the liquid for one parameter. The properties of the liquid are measured at least substantially simultaneously by another electrical method, where the properties of the liquid are measured using both a relative-value and an absolute-value measurement method.

Abstract: A sensing element (2) for sensing a fluid (50) composition and a method of using the sensing element (2) are provided. The sensing element (2) includes an electrode base (36) having a first electrode (4) and a second electrode (6) disposed on the electrode base (36); the first electrode (4) and a second electrode (6) being electrically isolated one another except through an external circuitry (64); the first electrode (4) and the second electrode (6) defining a gap (42) between one another such that electrical conduction through a fluid (50) within the gap (42) is proportional to the composition of the fluid.

Abstract: A method and apparatus for detecting an accumulation of particles with a medium such as the soot content in diesel engine oil including generating a first waveform at a first frequency and a first voltage level to produce a standing wave having a voltage null point where at least a portion of the standing wave is passed within a portion of the oil. Generating a second waveform at a second frequency and a second voltage level to place a signal associated with a second voltage null point at a detection location for determining the signal's null point voltage level. The percentage soot content of the oil may be determined by taking the ratio of the difference between the first voltage and the second voltage over the null point voltage at the detection point. This ratio is indicative of the percentage soot content. The first and second waveforms may be produced by a variable frequency microwave source that is coupled with a coaxial cable have a probe affixed to its distal end for immersion in the oil.

Abstract: A device for determining whether a lubricant to be examined effects the formation of a deposit on a sensor element has a sensor element for detecting values of at least one physical parameter of the lubricant. The sensor element is in contact with the lubricant. Furthermore, there is provided a potential difference source for applying a potential difference between the sensor element and the lubricant. Moreover, there is provided an evaluator for evaluating at least two values of the physical parameter which are detected at different potential states between the sensor element and the lubricant in order to thus determine whether the lubricant causes a deposit formation on the sensor element.

Abstract: A probe assembly for use in monitoring fluid conditions in real time in a transducer utilizing impedance spectroscopy and having two closely spaced tubular concentric electrodes. The electrodes have a surface area of about 8.1 to 10.8 cm2 spaced in the range of about 0.1 to 0.55 mm. In one embodiment a concentric outer tubular Faraday shield is employed for monitoring fluid in a non-metallic vessel. The probe assembly is particularly suitable for monitoring hydraulic fluid including automatic transmission fluid and mineral based engine oil for diesel and gasoline engines.

Abstract: A biological cell test method and apparatus employs a conventional perforated cell carrier which has a plurality of holes. Each hole has two metal electrodes. A cell is disposed in the hole to contact the two electrodes. The electrodes are connected to electric current or voltage. The electric current or field flows from one electrode through the cell to another electrode. Through the inherent impedance, inductance or capacitance of the cell, the presence or property reactions of the cell may be detected.

Abstract: A system for measuring oil condition in large engines includes a bypass valve that is installed in a lubrication system along a fluid line between an oil pan and an engine. The bypass valve communicates with a measurement chamber and when energized by a control module, the bypass valve diverts oil from the lubrication system to the measurement chamber. An oil condition sensor is disposed within the measurement chamber and is used to determine the condition of the oil that is diverted to the chamber. After the condition of the oil is determined, the bypass valve is energized to release the oil from the measurement chamber back into the lubrication system.

Abstract: An oil deterioration detection apparatus includes a sensor, an evaluation circuit, and a malfunction detecting circuit. The evaluation circuit has a determination circuit. The malfunction detecting circuit has a resistor and a switch. The evaluation circuit evaluates a condition of the oil based on a normal voltage. The normal voltage is measured when the switch is opened so that the resistor is not electrically conducted. The determination circuit determines whether the sensor malfunctions based on a relation between the normal voltage and a divided voltage. The divided voltage is measured when the switch is closed so that the resistor is electrically conducted in parallel with the sensor.

Abstract: An on-line method for determining the condition of low conductivity working fluids using alternating current, electro-impedance spectroscopy is provided by making measurements over a range of frequencies at temperatures at or above 50° C.

Abstract: Described herein is a sensing element for sensing a fluid composition comprising an electrode base having a first electrode and a second electrode disposed thereon; the first electrode and the second electrode being electrically isolated from one another except through an external circuitry; the first electrode and the second electrode being configured, dimensioned, and positioned to define a gap therebetween such that electrical conduction through a fluid within the gap is proportional to a composition of the fluid. A sensing assembly is also described including a combination fuel pressure regulator and composition sensor. Also described herein is a method of using the sensing element in sensing a fluid composition.

Abstract: A method by which contaminant (soot) content in Diesel engine oil is determined using electrical conductivity measurements of the Diesel oil at a high frequency, or by which contaminant (soot and/or water and/or anitfreeze) content is determined using the ratio of electrical conductivity measurements of the Diesel oil at a high frequency to the electrical conductivity measurements of the Diesel oil at a low frequency. Both the conductivity ratio and the high frequency conductivity are essentially independent of the brand of oil. High frequency is defined to be above 2 MHz whereas low frequency is defined to be D.C. to about 1 kHz.

Abstract: An apparatus for measuring the complex impedance of a fuel includes a sensing element in contact with the fuel. The sensing element is excited with an excitation signal of a predetermined frequency, preferably in a range of 10 kHz to 100 kHz. The induced signal is used to generate a phase and a magnitude signal indicative of the phase and magnitude of the complex impedance. From the phase and magnitude signals, the resistance and capacitance of the fuel can be calculated. Correction for variations in temperature of the electronics is provided, as is variable control to adjust the resolution of the magnitude signal required by fuels of varying content, such as varying ethanol content.

Abstract: An apparatus for measuring the complex impedance of a fuel includes a sensing element in contact with the fuel. The sensing element is excited with an excitation signal of a predetermined frequency, preferably in a range of 10 kHz to 100 kHz. The induced signal is used to generate a phase and a magnitude signal indicative of the phase and magnitude of the complex impedance. From the phase and magnitude signals, the resistance and capacitance of the fuel can be calculated. Correction for variations in temperature of the electronics is provided, as is variable control to adjust the resolution of the magnitude signal required by fuels of varying content, such as varying ethanol content.

Abstract: A primary, normally open, DC monitoring circuit with a circuit continuity test device is disclosed which will also test one or more additional sensors connected to the circuit. The sensing of lack of continuity or of a fault condition detected by an additional sensor governs the status of a single indicator, generally a warning light.

Abstract: A method and a sensor (1) for oil-in-water measurement, in particular for the oil industry. In an electric measuring cell (7, 12) a capacitance is measured as a measure of an oil concentration in the water flowing through or in the accumulation filter (16, 16a, 16b). In order to reduce the maintenance requirement, the measuring cell (7, 12) is automatically calibrated at recurring time intervals with clean water (FIG. 1) and/or flushed with water, possibly oil-contaminated, in the back-flushing direction (FIG. 2). Advantages of the invention are reduced signal drift, improved long-term reliability and a long service life without monitoring or filter exchange.

Abstract: The present invention relates to a process and device for the monitoring of fats and oils in the preparation of food, which provide for the exchange of oil or fat in a timely manner, before they have become harmful for human consumption. The proposed process for measurement distinguishes itself by the fact that the measurement is already taking place during the temperature adaptation of the sensor, whereby a measurement can take place which is particularly fast and thus suitable for use in practice. Along with this, the device is formed in such a manner that disturbances of the measurement can be largely eliminated.

Abstract: A probe assembly for use in monitoring fluid conditions in real time in a transducer utilizing impedance spectroscopy and having two closely spaced tubular concentric electrodes. The electrodes have a surface area of about 8.1 to 10.8 cm2 spaced in the range of about 0.1 to 0.55 mm. In one embodiment a concentric outer tubular Faraday shield is employed for monitoring fluid in a non-metallic vessel. The probe assembly is particularly suitable for monitoring hydraulic fluid including automatic transmission fluid and mineral based engine oil for diesel and gasoline engines.

Abstract: An engine oil contamination sensor includes a first sensing electrode and a second sensing electrode. A sensing area is established between the electrodes. The sensor is oriented in an oil pan such that the sensing are is completely submerged in engine oil. A microprocessor is connected to the sensing electrodes and includes a program for determining whether antifreeze is dispersed in the engine oil.

Abstract: There is provided a fluid dynamic bearing evaluating method capable of quantitatively observing a clearance between a shaft 3 and a housing 2 in an operating state and evaluating a fluid dynamic bearing 1 more in detail. This fluid dynamic bearing evaluating method is to evaluate the fluid dynamic bearing 1 by filling a space between the housing 2 and the shaft 3 with an uncharged lubricant, flowing a current through between the housing 2 and the shaft 3 and measuring an electrical resistance value of the fluid dynamic bearing 1 including the lubricant. According to this evaluating method, the lubricant placed between the housing 2 and the shaft 3 is not electrically charged, and therefore, the measured electrical resistance value has a correlation with the clearance between the housing 2 and the shaft 3, and the clearance can be quantitatively observed by this electrical resistance value.

Abstract: In a pair of electrodes where a potential difference is changed in accordance with acidity or basicity of oil, a reference electrode is made of cobalt or a cobalt alloy, and a sensitive electrode is made of tungsten or a tungsten alloy. The sensitive electrode is used in combination with the reference electrode. Accordingly, it is possible to provide a pair of electrodes for detecting the acidity or the basicity of the oil which use a novel electrode material not hazardous to the environment and at the same time, suited for use in a semiconductor fabrication technique.

Abstract: An engine oil contamination sensor includes a first sensing electrode and a second sensing electrode. A sensing area is established between the electrodes. The sensor is oriented in an oil pan such that the sensing are is completely submerged in engine oil. A microprocessor is connected to the sensing electrodes and includes a program for determining whether antifreeze is dispersed in the engine oil.

Abstract: A device for sensing oil condition includes an oil condition sensor that includes a first sensing plate separated from a second sensing plate by a spacer. Affixed to the first sensing plate and the second sensing plate is a platinum sensing electrode and a resistance temperature device. The sensing electrodes are separated by a gap that is filled with engine oil when the sensor is installed in an oil pan. A processor connected to the sensor can be used to determine when the engine is experiencing a first stage of oil degradation, a second stage of oil degradation, and a third stage of oil degradation. Each stage of degradation is characterized by a first sensor output signal trend, a second sensor output signal trend, and a third output signal trend, respectively.

Abstract: A structural body which, at least region-wise, has at least one area which is in contact with a liquid or a gas flowing past, and which, at least to a great extent, is provided with a surface patterning made of a plurality of randomly or irregularly distributed geometric forms, in particular pyramids. At least one such structural body be used in a capacitive sensor with which, in particular, the dielectric constants or the conductance of a liquid or a gas can be determined.

Abstract: An algorithm by which a time normalized oil condition trend (OCT) is developed. During engine off periods, while the engine is cooling, the vehicle's main computer program implements the trend algorithm according to the present invention by which engine oil conductivity (oil sensor output voltage) and temperature data are obtained in a specified temperature range, and are then input into a cool down equation to determine its coefficients using nonlinear regression. This cool down equation models oil conductivity as a function of temperature and is used at a specified time during an engine-on period to calculate an OCT point. Collectively, these OCT points determine the oil condition trend that is analyzed by a procedure called from the vehicle's main computer program to determine when an oil change is necessary.

Abstract: A system and a method for measuring capacitance of a capacitor having a dielectric material, such as a lubricating oil, disposed between the electrodes of the capacitor, where the dielectric material causes a double layer effect within the capacitor. A variable source is provided in series with a resistor to induce a change in a current flowing through the capacitor. A sensor converts the resulting current flow into a current value readable by a processor. The processor records a plurality of current values. An initial value is recorded to correspond to the induced change in the current. A leakage value is recorded after the current has exponentially decayed to approximate steady state. Multiple other current values are also recorded during the exponential decay. An intermediate value is then selected from among the multiple other current values based upon the initial value and the leakage value.

Abstract: A measuring device (1) is suggested for determining the quality of oils or fats, in particular for being used in conjunction with the preparation of foods, which device has a simple construction and is easy to handle. It comprises a measuring head (12) on which a sensor (5) is attached which measures the electric constant of the oil. The measured value is further processed in electronics of the device and a statement about the state of the quality of the oil is made. The measuring head (12) is attached via an attachment (11) to a housing (10) containing the measuring electronics, the energy supply and a display (2) for the determined state of the oil or fat.

Abstract: A monolithic sensor includes a reference channel and at least one sensing channel. Each sensing channel has an oscillator and a counter driven by the oscillator. The reference channel and the at least one sensing channel being formed integrally with a substrate and intimately nested with one another on the substrate. Thus, the oscillator and the counter have matched component values and temperature coefficients. A frequency determining component of the sensing oscillator is formed integrally with the substrate and has an impedance parameter which varies with an environmental parameter to be measured by the sensor. A gating control is responsive to an output signal generated by the reference channel, for terminating counting in the at least one sensing channel at an output count, whereby the output count is indicative of the environmental parameter, and successive ones of the output counts are indicative of changes in the environmental parameter.

Abstract: An apparatus for monitoring presence of hydrocarbon-based fluid is disclosed. It includes a body and a sensing cable mounted on the body in a wave-like shape, thus forming a plurality of sensing sections for detecting a layer of hydrocarbon on water. When contacting hydrocarbon, each of the sensing sections generates a signal and the signals add up before transmission to a signal receiver through a signal line.

Abstract: An apparatus and method for monitoring a highly electrically-resistive fluid is provided. The method includes applying across the fluid an AC signal that includes at least two different AC electrical potentials, with at least one AC electrical potential having a non-zero DC offset, measuring the fluid's electrical response at each applied potential, and analyzing the fluid quality and/or condition using the applied AC signal and the corresponding measured electrical responses. The invention finds application in conjunction with the on-line (i.e., while in use) monitoring of highly resistive fluids such as, e.g., lubricants, natural and/or synthetic motor oils optionally including standard additives and/or adjuncts, combustion engine fuels, other hydrocarbon-based fluids used in transportation and industrial applications, and the like.