Drexelbrook Controls, Inc.

Drexelbrook Engineering Company

Other

Ametek, Inc.

Frederick L Maltby

L Jonathan Kramer

Kenneth M Loewenstern

Steven R Petersen

Jonathan L Kramer

Robert J Sun

Jack G Benning, Jr

Howard S Hoopes

David M Stern

Richard G Hall

Yang Wang

Glen Mitchell

Norman Nardelli

Thomas E Meacham, Jr

Leslie D Horrocks, Deceased

Edward R Woerner

Mort Gorowitz

Glen L Mitchell

By Maureen Horrocks, Executrix

A sludge blanket level is determined in a waste water treatment clarifier using sonic pulse reflections. Additionally, using similar techniques, the clarity of the waste water is determined. A sonic pulse is directed into the waste water. Echos are generated as the pulse encounters the impedance mismatches indicative of changes in the density of the water. The echos are compensated for attenuation as a function of travel time through the water, energy lost due to prior peak reflections, and are processed to remove random signals using correlation techniques. A sludge blanket is selected from the compensated echo signal as a function of the size and location of echo peaks. Additionally, the clarity is determined as a function of the area under the echo signal between two points corresponding to predefined levels in the clarifier tank.

Method and apparatus for the sonic measurement of sludge and clarity conditions during the treatment on waste water

A sludge blanket level is determined in a waste water treatment clarifier using sonic pulse reflections. Additionally, using similar techniques, the clarity of the waste water is determined. A sonic pulse is directed into the waste water. Echos are generated as the pulse encounters the impedance mismatches indicative of changes in the density of the water. The echos are compensated for attenuation as a function of travel time through the water, energy lost due to prior peak reflections, and are processed to remove random signals using correlation techniques. A sludge blanket is selected from the compensated echo signal as a function of the size and location of echo peaks. Additionally, the clarity is determined as a flnction of the area under the echo signal between two points corresponding to predefined levels in the clarifier tank.

Method and apparatus for the sonic measurement of sludge and clarity

An ultrasonic measurement method in an ultrasonic measurement system having an ultrasonic transducer includes emitting an ultrasonic pulse from the ultrasonic transducer. An ultrasonic pulse is received in accordance with a pulse travel time wherein the amplitude of the received ultrasonic pulse varies according to the pulse travel time. A first electrical signal is provided representative of the received ultrasonic pulse wherein the amplitude of the first electrical signal varies in accordance with the pulse travel time. A second electrical signal is provided in accordance with the first electrical signal wherein the amplitude of the second electrical signal is substantially independent of the pulse travel time. In order to determine the second electrical signal variable amplification is applied to the first electrical signal in accordance with the travel time. A distance is determined according to the pulse travel time wherein the distance is representative of the distance between the transducer and a material surface.

Ultrasonic method for material monitoring

A sonic transducer shroud is shaped to present an inclined surface to rising bubbles and other matter during water treatment. Attached to the face of the sonic transducer, the shroud prevents the bubbles and other matter from being trapped on the transducer measurement surface and subsequently interfering with echo reception. The shroud has acoustic properties that are matched to the water such that the shroud is substantially acoustically transparent.

Transducer shroud for improved transducer operation in the treatment of

A high reliability instrument system includes means for applying a test condition to the instrument and for determining whether the instrument properly responds to the test condition, and means for inhibiting the generation of an instrument output in response to such testing. This provides verification that most of the instrument system components, but not the system output, are properly functioning. The system further includes means for overriding the output-inhibiting function when it is desired to test the entire instrument system including the system output. The instrument system may include a gap-type ultrasonic instrument, with the test condition comprising a pulse applied to one crystal, the effects of which are detected at the other crystal to determine sensor integrity. The system is preferably configured as a two-wire on-off instrument system, in which application of the test condition at a transmitter is controlled by signals applied to the two-wire signal loop at a remote receiver. The system may be implemented as a quasi-redundant system having radio frequency instrument and an ultrasonic instrument disposed to monitor the same condition, in which both instruments may be connected to a single type of receiver and tested in response to the same type of signal generated by such receiver.

High reliability instrument system

A multiple set point material condition monitoring system is responsive both to the level of material with respect to a sensor and the extent of material coating which has accumulated on the sensor. The system provides an output when a predetermined coating thickness has been exceeded, so that the sensor may be cleaned before the coating can accumulate to the extent where a false level output is generated. The systems include three electrode guarded sensors, a bridge comparing the sensor output with a reference, and a bridge reference which is automatically and repeatedly caused to assume a sequence of values corresponding to material condition set points, one of which causes an output when a predetermined coating thickness has occurred and another of which generates a level output. In one embodiment, separate outputs are provided corresponding to each set point. In another embodiment, a single tri-state output is responsive to both set points.

Coating responsive material condition monitoring system

An instrument system provides compensation for signal processing errors by processing both sensor signals and reference signals in a common signal processor. Reference signals may be provided which enable zero compensation, gain compensation, or both. The system outputs compensated signals to a two wire signal loop in either analog or digital form, and selects the form of output signal in accordance with digital input signals received from the signal wires. The system may be embodied as a radio frequency admittance instrument system for monitoring the condition of materials.

Error compensating instrument system with digital communications

A two-wire, admittance-responsive instrument system in which a transmitter, receiver and calibrator are connected by a two-wire transmission line is disclosed. The calibrator repetitively transmits a calibration enabling signal causing the transmitter to increment a reference admittance for comparison to a sensed admittance corresponding to a known physical condition. The calibrator monitors the bistable output signals transmitted by the transmitter in the calibration mode, which changes state when the incremented reference admittance bears a predetermined relationship to the sensed admittance. The calibrator may then transmit additional calibration enabling signals causing preload to be established for transmitter operation.

Remotely calibratable instrument system

A probe comprises a plurality of longitudinally extended conductors forming a probe electrode, a laterally displaced ground electrode and two laterally displaced active guard electrodes interposed between the probe electrode and the ground electrode. The conductors are surrounded by solid insulation and the probe guard electrodes are driven at substantially the same potential as the probe electrode. The probe is utilized to measure the condition of materials in which the probe is immersed.

Probe system for measuring the condition of materials

In an instrument system consisting of a transmitter in one location and a receiver in another location connected by a transmission medium, fail-safe operation is obtained by restricting the output of the transmitter to well-defined levels and interpreting any substantial departure of the received signal from these well-defined levels as a failure. When a failure is detected, alarms or other equipment may be activated, including a control circuit which causes replacement of the defective transmitter or transmission medium, thereby restoring the system to service. An embodiment wherein the transmitter is an admittance-responsive transmitter in a two-wire current loop for monitoring the condition of materials is described.

Fail-safe instrument system

A hollow probe which is adapted to respond to the degree to which a pipe is filled with fluid includes the use of a tubular conductive probe measuring electrode and a pair of tubular conductive guard electrodes axially displaced from the probe electrode. The tubular electrodes are hollow and are adapted to form a fluid conducting portion of the fluid-carrying pipe. The probe electrode and guard electrodes are separated by solid insulation. The guard electrodes are separated from sections of the pipe on either side of the hollow probe by solid insulation. The guard electrodes are exposed to the contents of the pipe and, by driving the guard electrodes at substantially the same potential as the probe electrode, the adverse effects of a coating of fluid adhering to the probe are substantially eliminated. Also disclosed is RF admittance-responsive circuitry which responds to the electrical characteristics of the contents of the probe and pipe, and which is adapted to drive the guard electrodes at substantially the measuring potential applied to the probe measuring electrode. By capacitively coupling the admittance-responsive circuitry to the contents of the probe, a substantial improvement in the ability of the system to tolerate conductive coating of the probe is achieved.

RF Admittance apparatus and method for monitoring the contents of a pipe

A probe for the measurement of the level of conductive materials within a conductive vessel is disclosed which is particularly suitable for the measurement of the level of conductive granular materials such as coal or other minerals or plastics or vegetable matter which are conductive. In a preferred embodiment the probe comprises a conductive steel core covered with a layer of insulating plastic and covered further with a layer of a semi-conductive material which preferably comprises a plastic which has been partially filled with a conductive material such as carbon black. Other embodiments wherein the probe may comprise a conductive plate covered by insulation further covered by a similar semi-conductive layer are also disclosed. Reference is made to prior art disclosures of circuitry and theory which enable the use of the probe of the invention.

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Jenkintown, PA, United States of America

Frederick L Maltby