Abstract: The invention relates to a method for determining the ionic strength and/or the specific weight of aqueous liquids and a reagent for this purpose, the composition of the reagent being such that the color change indicating the ionic strength is essentially directly dependent on the specific weight of the liquid to be determined and not on a pH shift.

Abstract: A method and apparatus for detecting objects in computed tomography (CT) data are disclosed. Sheet-shaped objects such as sheet explosives can be detected by analyzing a neighborhood of voxels surrounding a test voxel. If the density of the test voxel is sufficiently different from the mean density of the neighboring voxels, then it is concluded that the test voxel is associated with a sheet object. Sheet objects can also be detected by eroding the CT data so as to eliminate voxels associated with thin objects. Remaining objects are then subtracted from the original data, leaving only thin sheet-shaped objects. Erosion of the data can be performed by identifying a neighborhood of voxels surrounding a voxel of interest. If the number of voxels having densities below a predetermined threshold exceeds a predetermined number, then it is assumed that the test voxel is a surface voxel and is removed from the object.

Abstract: The relative density of a sample of a supply gas under test is determined by measuring an atmospheric pressure and a pressure differential for the reference gas and the sample gas as each is passed through a small orifice (16) with smooth walls, such as a pore formed in a sapphire jewel. The pressure measurements are made on a time base determined during the reference gas cycle. A microcontroller (15) then computes a relative density for the sample gas based on a known relative density for the reference gas and a ratio of pressure factors for the sample gas and the reference gas in a system operating at in a range from about 1 to about 6 psig.

Abstract: An accurate method and apparatus for installing blown-in-place insulation to a predetermined density and R-value includes the use of a removable container of known unfilled weight and volume located between wall studs during the blowing operation. By removal of the container after filled, and determining its fill weight by weighing it, the density of the insulation is calculated and correlated, if desired, to R-value. If the calculated density is not acceptable, the container is emptied and is reinserted in the cleaned out cavity between the studs. Appropriate adjustments to one or more operating parameters are made until the desired density through further filling of the container and weighing it is achieved. Once achieved, the space to be filled is filled with blown-in-place insulation using the adjusted parameter values.

Abstract: A microwave resonator for connection to an instrument for measuring the density and/or moisture profile in the longitudinal direction of a sample, which microwave resonator has a through-hole (3) at right angles to its area extent, which through-hole (3) is bounded by metallic walls (4) extending in the longitudinal direction, distinguishes itself in that the interior (1) of the resonator is essentially flat, with a thickness which is considerably less than the lateral dimensions at right angles to it, and in that the resonator is filled with a dielectric.

Abstract: A method and apparatus are described for controlling demand of a fluid. The method includes measuring a fluid supply pressure in a supply pipe, determining that the fluid supply pressure is lower than a predetermined threshold supply pressure, and directing a control signal from the fluid information unit to the one or more demand control units to reduce demand for the fluid. In addition, a method and apparatus are described for measuring density of a fluid flowing through a demand pipe. The method includes determining that fluid flow through the demand pipe is stable, measuring fluid flow rate through the demand pipe, preventing the fluid from flowing into the demand pipe for a sample period of time, measuring a drop in fluid pressure in the demand pipe during the sample period, and determining the density from the measured pressure drop. Also, a utility meter for metering a fluid flowing through a supply pipe and a demand pipe having an audible indicator to provide an audible signal to a user is described.

Abstract: A differential level hydrometer reduces the possibility for user error and provides an accurate, predictable, easy to use, reliable instrument for measuring the density (specific gravity) of a liquid. The differential level hydrometer works by automatically measuring the level of a liquid within a vessel and floating, in the liquid, a calibrated float having a precisely known volume and density. The instrument automatically measures the level of the liquid within the vessel while the float is floating in the liquid, and automatically calculates the density (specific gravity) of the liquid based on the two measured levels and the volume and density of the float. Temperature and meniscus correction may be used to improve repeatability and accuracy.

Abstract: Reagent for determining the ionic strength and/or the specific weight of aqueous liquids and a reagent for this purpose, the composition of the reagent being such that the color change indicating the ionic strength is essentially directly dependent on the specific weight of the liquid to be determined and not on a pH shift.

Abstract: Apparatus and method for removing bubbles from a discrete sample of a temperature-sensitive liquid, particularly a photographic emulsion. A container having a bottom and side walls defines a sample area containing the liquid to be sampled and is made of a substantially acoustically transparent material. The container is removably mounted to a receptacle such that the bottom and at least a portion of the side walls are immersed in a fluid bath. The fluid bath is heated to maintain the liquid at a predetermined temperature greater than ambient temperature. An ultrasonic device spaced from the container directs ultrasonic waves through the fluid toward the bottom of the container to degas the liquid.

Abstract: A system and method for obtaining a fluid density of a fluid in a tank includes at least two sensor/transmitter assemblies to obtain fluid pressure measurements at different fluid levels in the tank. After the respective fluid pressures are obtained, the fluid density is calculated as a function of the respective fluid pressure measurements. The sensor/transmitter assemblies have substantially similar variation characteristics so that possible measurement variations are eliminated during fluid density calculations.

Abstract: A display device of a storage battery for optically displaying a condition of an electrolytic solution stored in a casing of the storage battery comprises a pillar member having a transparent body having one end and other opposite end, the one end of the pillar member being engaged at an upper surface of the casing in a usable state so that the other opposite end thereof projects into the casing. An inclined end surface of the opposite end side thereof is inclined to a side surface of the pillar member at a predetermined angle so that an incident light transmitting from the one end side thereof permeates through the inclined end surface or is reflected thereby according to the condition of the electrolytic solution which is in contact with the inclined end surface.

Abstract: A pair of thickness-shear mode resonators, one smooth and one with a textured surface, allows fluid density and viscosity to be independently resolved. A textured surface, either randomly rough or regularly patterned, leads to trapping of liquid at the device surface. The synchronous motion of this trapped liquid with the oscillating device surface allows the device to weigh the liquid; this leads to an additional response that depends on liquid density. This additional response enables a pair of devices, one smooth and one textured, to independently resolve liquid density and viscosity; the difference in responses determines the density while the smooth device determines the density-viscosity product, and thus, the pair determines both density and viscosity.

Abstract: A compaction device for determining envelope and bulk densities of sample materials. The device uses a rotating sample cylinder and a plunger positioned within the cylinder. The force on the plunger is measured as the plunger advances in the cylinder. The position of the plunger at which a predetermined level of force is applied thereto is determined. Envelope density is determined from the difference in the advance of the plunger when the cylinder is partially filled with a dry flowing medium and when a sample material such as a rigid object is added into the medium. Bulk density is determined from the difference in the advance of the plunger when the cylinder is empty and when the cylinder contains a sample material such as a powder.

Abstract: An automatic analyzer is used to determine out of range specific gravity of adulterants in a urine sample. An aliquot of the urine is mixed with a buffer and ion detector and thereafter with a polymer activator for ion detection. The mixture is analyzed by setting a spectrophotometer in the automatic analyzer at about 600 nanometers, setting the calibrating value for specific gravity at 1.000 and 1.0500 and reading a color change to determine the presence of adulterants.

Abstract: A pair of thickness-shear mode resonators, one smooth and one with a textured surface, allows fluid density and viscosity to be independently resolved. A textured surface, either randomly rough or regularly patterned, leads to trapping of liquid at the device surface. The synchronous motion of this trapped liquid with the oscillating device surface allows the device to weigh the liquid; this leads to an additional response that depends on liquid density. This additional response enables a pair of devices, one smooth and one textured, to independently resolve liquid density and viscosity; the difference in responses determines the density while the smooth device determines the density-viscosity product, and thus, the pair determines both density and viscosity.

Abstract: The present invention provides a reagent composition for measurement of ionic strength of liquid samples (especially for measurement of specific gravity of urine), which contains at least one phosphoric diester, at least one pH buffering agent, and at least one pH indicator. The present invention also provides a test tool containing the reagent composition which may be a test strip made by impregnation, coating, or printing of the composition. The reagent composition and the test tool are convenient and less susceptible to pH and temperature of the samples, measurement timing, etc. The compounds shown by the following general formula (1): ##STR1## wherein R.sub.1 and R.sub.2 in the formula (1) represent straight or branched alkyl groups containing 4-20 carbon atoms, phenyl groups which may be substituted, benzyl groups which may be substituted, or groups containing polyalkylene glycol chains, are preferable as a phosphoric diester.

Abstract: A pair of flowmeters having unequal flow carrying capabilities are effectively connected in parallel to receive a material flow. The material flow through the flowmeters supplies output signals to associated meter electronics which derives mass flow and other information for each meter. The meter electronics is pre-programmed with information regarding the physical characteristics of each flowmeter. The meter electronics uses the pre-programmed information and the derived material flow velocity for each meter and other information to determine the viscosity for the material in the flowmeters.

Abstract: Disclosed are a method and device for the determination of specific gravity in aqueous systems, particularly urine. The invention improves upon the known systems for detecting specific gravity by the use of a polyelectrolyte polymer and pH indicator by the addition of a crown ether ionophore which enhances the ability of the reagent system to indicate the fluid's specific gravity.

Abstract: An apparatus and method for measuring the volume and calculating the envelope density of an object of known weight. The apparatus has a hollow sample cylinder of known interior diameter mounted to a motor for rotation about its horizontal axis. A dry flowing medium is placed in the sample cylinder and a plunger is removably positioned therein. The plunger is mounted to another drive motor for axial movement within the sample cylinder to compact the dry flowing medium. A load cell connected to the plunger measures the force on the plunger as it advances in the sample cylinder. Control means responsive to the load cell determines the position of the plunger in the sample cylinder at which a known force is exerted on the plunger. The control means also calculates the volume of the dry flowing medium in the sample cylinder both with and without the object positioned therein and divides the difference in the volumes into the weight of the object.

Abstract: A method determines the amount of the fluid content with a smaller specific gravity in an airtightly sealed flexible container containing contents with different specific gravities that are automatically separated from each other when held to a stationary state. The amount of said content is determined by externally applying pressure to the airtightly sealed flexible container to increase the inner pressure thereof and collecting data on the fluid content with the smaller specific gravity.

Abstract: A method and apparatus for measuring the density or specific gravity of a fluid sample uses a single sensor. A reservoir contains another fluid of known density which is not miscible with the fluid sample. Sensors are disposed proximate to the reservoir to detect the passage of the fluid sample through the non-miscible fluid medium. A microprocessor monitors the sensor and calculates the specific gravity of the fluid sample. The microprocessor measures the amount of time one sensor is eclipsed as the fluid sample droplet falls through the fluid medium and calculates the density or specific gravity based on that amount of time. The microprocessor also may measure a second amount of time, the time required for the fluid sample to traverse through the fluid medium between two sensors. The microprocessor can use this second amount of time to measure the fluid droplet diameter or size. The microprocessor corrects the calculated density or specific gravity for any deviation caused by the size of the fluid sample.

Abstract: A powder flow rate is measured based on a simple construction so as to provide method and apparatus for measuring the powder flow rate for example of a powder coating material, requiring less maintenance cost and facilitating change of color of the coating material. In the method for measuring powder flow rate: a density .rho.1 of the powder within a tank is measured; the powder is drawn out from the tank into a conveying tube; a detecting fluid is blown at a flow rate Qf into the conveying tube a density .rho.2 of the powder in the conveying tube is measured; and a powder flow rate Fm is measured based on an equation of Fm=Qf.multidot..rho.1.multidot..rho.2/(.rho.1-.rho.2). The density .rho.1 of the powder in the tank may be measured by providing a pair of pressure measuring devices at different heights within the tank. The density .rho.

Abstract: An apparatus and method are provided for determining the relative density of a flowing fluid based upon the ratio of the fluid's flow rate before and after a material is added. Using analog or digital components, two signals are generated, representing the two flow rates, a first ratio of the two signals is derived, the ratio is compared to a constant, a second ratio of a second constant to the first ratio is derived, and the result of the comparing step is multiplied by the second ratio to generate a density signal representative of the relative density of the fluid after the material has been added.

Abstract: A device for determining the density of liquids and gases uses an actuator to physically excite a sample of the material being tested. The oscillations induced by this excitation are detected by a sensor and amplified by an oscillation amplifier, and the amplified signal is used to drive the actuator in a closed-loop fashion. To compensate for errors in the density measurement process arising from non-ideal viscous effects of the sample, a phase change circuit or inverter may be shunted into the amplifier circuit to change the phase of the excitation signal. By observing the effects of the excitation phase change on the oscillation frequency of the sample, the sample's viscosity can be measured, and the system can compensate for its effects.

Abstract: Fluid level in a container is determined using a single pressure transducer connected to a portable body. The body contains a computer having a memory in which fluid level-to-fluid volume conversion data are stored for different shapes of containers so that fluid volume can be readily obtained for the shape of the respective container once fluid level is determined. These features allow a single monitoring apparatus to be used for monitoring different types of containers. The apparatus preferably includes a radio so that multiple apparatus can communicate in a system with a central remote operator interface device. Fluid level is determined by dividing a pressure reading from the bottom of the fluid by a fluid density determined from two prior pressure reading taken across a known distance (density equals the difference between the two readings divided by the distance).

Abstract: A method for determining the relationship between the density of a multi-component fluid mixture comprising a number of known components and the concentration of one of the components of the fluid mixture. The method comprises the steps of:(i) determining a first and a second density-concentration relationship to define the relationship between the density of the fluid mixture and the concentration of the component at first and second known temperatures T.sub.1 and T.sub.2, respectively;(ii) measuring the temperature T of the mixture;(iii) determining a temperature ratio value according to the relationship ##EQU1## (iv) choosing a component concentration value C.sub.i ; (v) determining first and second density values .rho.(C.sub.i, T.sub.1) and .rho.(C.sub.i, T.sub.2) by inputing the component concentration value C.sub.

Abstract: A device for measuring the density of the fluid flowing in a closed passage includes a rotor whose speed of rotation is directly dependent on the rate of flow of the fluid. The rotor is connected to an activatable and deactivatable brake means which has an adjustable braking force. Depending on the setting of the brake means, the brake is operative to cause a greater or smaller lag in the rotary speed of the rotor in relation to an unbraked rotor or a rotor braked with a smaller force. The measuring means is operative to determine the resultant different rotational speeds of the rotor and the different in these speeds is a measurement of density.

Abstract: A method of partitioning a pre-selected phase of a sample of liquid having a plurality of phases of differing densities, a separation device and a tube containing the separation device. The sample of liquid is placed in a first chamber of a linear tube that is separated from a second chamber by a separation device. The separation device slidably engages the interior surface of the tube in an essentially fluid-tight manner and has an axial orifice on the longitudinal axis of the tube that is in fluid flow communication with a flow-restriction channel. The phases are ordered concentrically by rotating the tube around its longitudinal axis e.g. in an axial centrifuge. The volume of the first chamber is reduced by movement of the separation device within the tube, that phase of the liquid located axially within the first chamber flowing into the axial orifice and passing through the flow-restriction channel into the second chamber.

Abstract: Fluid level in a container is determined using a single pressure transducer connected to a portable body. The body contains a computer having a memory in which fluid level-to-fluid volume conversion data are stored for different shapes of containers so that fluid volume can be readily obtained for the shape of the respective container once fluid level is determined. These features allow a single monitoring apparatus to be used for monitoring different types of containers. The apparatus preferably includes a radio so that multiple apparatus can communicate in a system with a central remote operator interface device. Fluid level is determined by dividing a pressure reading from the bottom of the fluid by a fluid density determined from two prior pressure reading taken across a known distance (density equals the difference between the two readings divided by the distance).

Abstract: Method and apparatus for determining jet fuel density. A microprocessor monitors the temperature, velocity of sound and dielectric constant of a jet fuel. The microprocessor determines the type of jet fuel and the density of the fuel using data from jet fuel samples of a known density and a least-squares-fit of the test data.

Abstract: Fluid level in a container is determined using a single pressure transducer connected to a portable body. The body contains a computer having a memory in which fluid level-to-fluid volume conversion data are stored for different shapes of containers so that fluid volume can be readily obtained for the shape of the respective container once fluid level is determined. These features allow a single monitoring apparatus to be used for monitoring different types of containers. The apparatus preferably includes a radio so that multiple apparatus can communicate in a system with a central remote operator interface device. Fluid level is determined by dividing a pressure reading from the bottom of the fluid by a fluid density determined from two prior pressure reading taken across a known distance (density equals the difference between the two readings divided by the distance).

Abstract: A method and apparatus is provided for measuring the volume and density of an object, including a living being, which avoids the necessity of immersing the subject in a liquid medium. Where the subject is a living being, the percentage of body fat may readily be determined from the density value. The density of the subject is measured by recording the weight of the subject for several different temperatures of a fluid, preferably air, surrounding the subject. The apparent weight change of the subject at the different measured temperatures of surrounding air represents changes in the buoyant forces exerted by the air on the subject at different air densities. The buoyant force acting on the subject is calculated from these measurements, and the volume of the subject is determined from its relationship with the buoyant force. The density of the subject can then be calculated from the volume and weight parameters.

Abstract: A method and apparatus measures the gas bubble content of a flowing fluid on a continuous basis without extracting a sample of the fluid. A flowing fluid flows into a density sensor via a temperature and pressure sensor where the temperature, pressure and density of the fluid are determined. As the fluid exits the density sensor, a second pressure sensor determines the pressure of the exiting fluid. The outputs of the sensors are amplified and then input into a data processor. An operating panel supplies required constant data regarding the fluid and gas. The data processor calculates the gas bubble content using the above information in accordance with a predetermined formula.

Abstract: The specific density of the liquid/air mixture is measured at successive levels within the reception vessel for the liquid using a reference measurement (Io) representing the specific density of the degasified liquid within a reference measuring path. The ratio of each obtained density value measurement and the reference value is calculated for each measuring level and multiplied with the specific density of the liquid to allow an accurate measurment of the overall liquid volume or flow-rate. Preferably the reception vessel (1) has a respective measuring electrode (El . . . En) at each measuring level with a common counter electrode (Eo) coupled to an oscillator (4) via a constant voltage circuit (5) and a coupling capacitor (6). Each measuring electrode (El-En) is coupled via a multiplexer (7) and an active rectifier (9) to an A/D converter (10) coupled to a microprocessor (11) controlling a read-out display (12).

Abstract: A light-weight density sensor has a rigid open structure that does not impede fluid flow and provides the ability to accurately and reproducably measure dielectric constant and densities over long distances without interference from connecting coaxial cables during periods of vibration and thermal shock. A novel immersion cell and an oscillator circuit provide a variable frequency output related to the dielectric constant of the cryogen within the immersion cell and from which the density of the cryogen can be determined. The immersion cell comprises an elongated electrode located centrally within an open outer electrode formed by a plurality of elongated conductors spaced around and from the central electrode conductor. The open outer electrode does not impede the flow of cryogen into the immersion cell and by its structure permits accurate density determinations dependent upon the dielectric constant of cryogen present within the cell.

Abstract: A method of determining the specific gravity of a fermentable liquor during fermentation is disclosed. Specific gravity is determined from measurements of original gravity, velocity of sound, and temperature.

Abstract: The specific gravity, l, of a fluid of interest is determined based on thermal conductivity, k, and specific heat, c.sub.p, of the fluid of interest. An embodiment uses proximately positioned resistive heater and thermal sensor elements coupled by the fluid of interest. Pulses of electrical energy are applied to the heater of a level and duration such that both a transient change and a substantially steady-state temperature occur in the sensor. The k of the fluid of interest is determined based upon sensor output at steady-state elevated temperature, c.sub.p of the fluid of interest is determined based upon the rate of change of sensor output during a time interval of transient temperature change in the sensor, and l is determined from k and c.sub.p.

Abstract: The method and apparatus for determining the density of a gas by measuring the time for a predetermined its flow through a sub-sonic square-root restrictor, such as a venturi, the rate of increase or decrease of the pressure in a reference chamber, a semi-continuous measurement means utilizing a motor driven, constant rate-of-movement piston being disclosed as well as a continuous density measurement means including a sub-sonic square-root restrictor followed, in fluid flowing fashion by a sonic restrictor venting to the atmosphere.

Abstract: A densimeter is provided having a pump which impels a liquid at a constant volume through a fixed orifice. A pressure transducer measures the pressure drop of liquid across the orifice and sends a signal to a microprocessor. A microprocessor determines the density of the liquid which is equal to the pressure drop divided by a constant times the square of a volumetric flow impelled by the pump.

Abstract: The present invention relates to a method for determining the density of a liquid using a falling needle viscometer. The viscometer includes a vertical cylinder which is filled with the liquid the density of which is to be determined. Using a funnel at the top of the cylinder, a first needle having a known density is allowed to fall through the liquid in the cylinder. The time that the needle falls between two marks, or transducers, spaced on the cylinder a known distance is measured from which the velocity of the needle through the liquid is calculated. Then a second needle having the same dimensions as the first and a known density different from that of the first needle is allowed to fall through the liquid. The time that the second needle falls between the two marks on the cylinder or transducers is measured and the velocity of the second needle through the liquid is calculated.

Abstract: A cryogenic density and mass-flow measurement system incorporating a high-speed microprocessor-based cryogenic fluid density instrumentation that is based on the rigorous application of the molecular dielectric theory, using a dielectric susceptibility function in the application of the Clausinus-Mossotti formula, and the introduction of the quantitation of a new susceptibility parameter k which serves to bridge the gap between the theoretically rigorous molecular dielectric equation and the macroscopic dielectric equation. The operating principle is formulated on a differential dielectric measurement approach with a new algorithm which provides for automatic adjustments for polarizability and stray capacitance changes. High precision digital density measurement is achieved over a wide range of cryogenic fluid states ranging from supercritical through subcritical to the slush phase.

Abstract: A method and apparatus for continually measuring the specific gravity of a flow liquid. The liquid is caused to flow across a flat measurement surface defined by a light transmissive shelf member. The measurement surface, i.e. the interface between the shelf member and liquid sample thereon, is illuminated by rays incident at angles greater than and less than a critical angle to reflect a boundary line whose position is dependent on the critical angle and thus the specific gravity of the liquid sample. The reflected boundary line is projected onto a photovoltaic surface which, together with detector electronics, determines the position of the boundary line with respect to a boundary line position associated with a reference liquid. The difference in boundary line position is used by the detector electronics to determine the specific gravity of the sample by a table lookup procedure.

Abstract: A battery which facilitates the measurement and recording of data is provided. The battery has a transparent casing wall and a scale attached to the wall for measuring the level of electrolyte within the battery. The scale contains first measuring indicia for measuring the distance the electrolyte level falls below a high level mark, and second indicia aligned literally opposite and having values, for example, specific gravity value correction factors, correlating to those of the first indicia.

Abstract: A cleaning device serves for cleaning sensing or sensor rollers which are mutually biased towards each other and between which travels a fiber sliver. Roll cleaning is effected by means of a scraper blade which, in accordance with the invention, is moved intermittently into a scraping position and away therefrom. This provides the advantages of reduced wear on the scraper blade provided at the cleaning device and also reduced wear on the peripheral surface of the associated sensing or sensor roller which is to be cleaned.

Abstract: A densimeter is provided having a pump which impels a liquid at a constant volume through a fixed orifice. A pressure transducer measures the pressure drop of liquid across the orifice and sends a signal to a microprocessor. A microprocessor determines the density of the liquid which is equal to the pressure drop divided by a constant times the square of a volumetric flow impelled by the pump.

Abstract: An apparatus is disclosed for gravity separation of comminuted solid particles. It has a transparent pipe (18) through which water flows upwards at a controlled velocity to float grains of a given size and specific gravity but to maintain lighter particles in a funnel on top of the pipe. The pipe is enclosed in a housing in which a water level can be raised or lowered to coincide with a mark on a scale indicative of the instant lowermost gravity of particles passing downwards through the pipe (18). The device is of a simple structure and provides the possibility of the readout of the specific weight of the accepted particles.

Abstract: This invention relates to a method for making porous metal plasma sprayed abradable seals. Radiation transmission techniques are utilized to determine the as-sprayed density of a deposit containing metal and polymer powder particles. Based on the measuring density, a mathematical prediction is made of what the surface hardness of the sprayed deposit will be after it has been machined and then heated to remove the polymer powder particles. If the predicted hardness is outside of the desired range, changes are made in the plasma spray parameters.

Abstract: A freely rotatable turbine is placed in the path of flowing fluid to drive the turbine at an angular velocity that, at steady state, is dependent upon the linear velocity of the flowing fluid. A transient condition is created in the angular velocity of the turbine. The time constant of the transient condition is determined. The time constant is representative of the density of the flowing fluid--the shorter the time constant, the higher the density and vice versa. The transient condition is created by disturbing the free rotation of the turbine, namely, by imnpairing free rotation to reduce the angular velocity of the turbine to zero, and then permitting the turbine to return to free rotation.

Abstract: A method and apparatus for controlling the density of a foam. The method involves measuring the electrical conductivity of a foam wherein the electrical conductivity of the foam varies with the density thereof and adjusting the density of the foam in response to the measured electrical conductivity to prepare a foam having a desired density. The apparatus comprises means for generating and applying a foam, said means being connected by an enclosed pathway. Located within the enclosed pathway is an electrical conductivity sensor. The conductivity sensor is electronically connected to a translation means. The conductivity sensor provides an electrical signal, related to conductivity of the foam, to the translation means. The translation means is connected to a gas flow controlling means.

Abstract: A method for determining the density of coal or other bulk material in a stockpile includes boring a calibration hole into the pile and collecting at least a portion of the cuttings thus obtained into a container. A series of readings are taken within the container with a nuclear depth-density gauge, and the weight of the cuttings and container volume is measured. The measured weight and volume are compared with the gauge readings to calibrate the gauge. A test hole is then bored substantially to the bottom of the stockpile, and a section of steel casing is inserted and partially pressed into the hole. A second section of casing is attached to the first and similarly pressed into the hole. In this manner, casing is extended the full depth of the hole. Readings are then taken at various depths therein with the nuclear gauge. From the data thus obtained, average density throughout the pile is determined.