Ultrasonic cavitation sensor

Abstract

An apparatus for detecting cavitation in a liquid flowing through a conduit within a housing includes an ultrasonic transducer system having one or more ultrasonic transducers mounted to the housing and arranged to acoustically communicate with the liquid, and control electronics connected to the ultrasonic transducer system. The control electronics are configured to drive the transducer system to transmit an ultrasonic signal through the flowing liquid, and the transducer system receives the ultrasonic signal and generates an electronic cavitation detection signal representative of the intensity of the received ultrasonic signal. The control electronics processes the cavitation detection signal to provide a cavitation measurement signal indicative of whether the ultrasonic signal has interacted with one or more cavitation bubbles, evaluates the cavitation measurement signal to determine whether one or more alarm conditions are satisfied, and is further configured to output an alarm signal when each of the cavitation alarm conditions is satisfied.

Description

Technical Field

[0001]

[0001] (Cross - Reference to Related Applications) This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 356,201, filed on June 28, 2022, the entire disclosure of which is incorporated herein by reference.

[0002]

[0002] (Field of the Invention) This disclosure relates to sensors for detecting cavitation and other characteristics of flow through liquid pumps and liquid pipe systems.

Background Art

[0003]

[0003] Cavitation is a phenomenon that frequently occurs in liquid pumps and pipe systems. Cavitation can be caused by restrictions in the flow within the pump or pipe, or by other conditions that generate low pressures leading to the formation of cavitation vapor bubbles. Cavitation vapor bubbles are different from ordinary bubbles in that the cavitation bubbles or voids are composed of the vapor of the surrounding liquid medium. For example, in pumps and pipe systems for water, cavitation vapor bubbles are composed of water vapor (i.e., low - temperature vapor) rather than air. Cavitation vapor bubbles collapse on the surface of the pump impeller, valve, or pipe, and can cause surface damage due to the extreme local pressures involved. The detection of cavitation is important for controlling the occurrence of cavitation and minimizing damage to costly components.

[0004]

[0004] Currently, cavitation is detected by an indirect detection method. It is known to detect cavitation by an acoustic sensor that listens for the sound generated by collapsing cavitation bubbles when the cavitation bubbles collide with the surface of a pump, valve, pipe, or other component of a liquid flow system. Another known method for indirectly detecting cavitation is to detect vibrations on a pump housing or pipe. Further methods for indirectly detecting cavitation include detecting significant changes in pump impeller speed or current draw, or measuring significant pressure drops in a liquid flow system. The known methods described above are of limited value in preventing such damage because cavitation vapor bubbles cause damage to system components, so they detect cavitation artifacts (e.g., noise, vibration, pump behavior). The use of acoustic sensors is not suitable for noisy environments.

[0005]

[0005] Cavitation can be detected directly by visual observation, but this requires that a transparent pipe be used in the liquid flow system and that the cavitation vapor bubbles be large enough to enable visual or optical observation.

[0006]

[0006] An improved solution for detecting cavitation is needed.

Summary of the Invention

[0007]

[0007] The present disclosure provides an apparatus and method for directly detecting cavitation bubbles in a liquid flowing through a conduit before the cavitation bubbles collapse on a surface.

[0008]

[0008] In one embodiment, the cavitation sensor module can include a pipe segment adapted to be installed within a pipe of a liquid flow system, one or more first transducer plugs each having a first ultrasonic transducer for transmitting an ultrasonic signal, one or more second transducer plugs each having a second ultrasonic transducer for receiving an ultrasonic signal from a paired first ultrasonic transducer, and a controller circuit board assembly connected to each of the first ultrasonic transducers and each of the second ultrasonic transducers. The cavitation sensor module can further include an enclosure for protecting the first and second transducer plugs and the controller circuit board assembly and securing the transducer plugs and the controller circuit board assembly to the pipe segment.

[0009]

[0009] The controller circuit board assembly can include an electronic controller and associated circuitry configured to execute stored programming instructions to drive each of the first ultrasonic transducers and process cavitation detection signals generated by each of the second ultrasonic transducers to establish a cavitation measurement signal. The electronic controller can execute stored programming instructions to compare the cavitation measurement signal to a predetermined cavitation threshold. The controller can be programmed and configured such that an alarm is issued by the controller when the amplitude of the cavitation measurement signal drops below the cavitation threshold. The intensity of the ultrasonic signal generated by each of the first ultrasonic transducers and the gain applied to the cavitation detection signal generated by each of the second ultrasonic transducers when the ultrasonic signal is received can be controlled and adjusted by the controller. The number of bubbles present in the flowing liquid and / or the accumulation of cavitation events can be calculated by the controller to provide additional information to the user.

[0010]

[0010] The enclosure can be a multi-piece enclosure having a plurality of parts that can be disassembled and assembled to install a cavitation sensor module within a liquid flow system. In one embodiment, the enclosure includes a central part sized to receive a first radial portion of a controller circuit board assembly and a pipe segment, a cover part removably attached to the central part and sized to cover the controller circuit board assembly, and a fixing part removably attached to the central part and sized to receive a second radial portion of the pipe segment that faces the first radial portion of the pipe segment to fix the enclosure onto the pipe segment.

[0011]

[0011] In another embodiment, the cavitation sensor device is similar to the sensor module summarized above, except that the control electronics are housed within a sealed control unit located remotely from a housing (e.g., a pipe segment, a pump housing, a valve housing, a fitting, or other housing) in which the liquid flow conduit is located.

[0012]

[0012] In a further variation, the cavitation sensor device does not include its own housing that defines a liquid conduit and is installed on an existing component housing (e.g., a pipe, a pump housing, a valve housing, a fitting, or another housing) within the liquid flow system. Further variations include non-invasive clamp-on and bond-on variations.

[0013]

[0013] The cavitation detection device of the present disclosure may include a user interface connected to a control electronic device, such as an external computing device. The user interface may be configured to display a cavitation measurement signal and / or a value representing the instantaneous intensity of the cavitation measurement signal. The user interface may be configured to receive a first variable user input for establishing a cavitation alarm set point. The user interface may also be configured to receive a second variable user input for establishing a cavitation error count setting to reduce nuisance alarms.

[0014]

[0014] The nature and mode of operation of the present disclosure will now be described in more detail by the mode for carrying out the following invention with reference to the accompanying drawings.

Brief Description of the Drawings

[0015]

Figure 1A

[0015] It is a schematic diagram of an ultrasonic cavitation sensor according to an embodiment of the present disclosure, viewed along the axial flow direction of a pipe conduit associated with the cavitation sensor, in which there are no cavitation bubbles in the liquid flowing through the pipe.

Figure 1B

[0016] It is a schematic diagram similar to FIG. 1A in which there are cavitation bubbles in the liquid flowing through the pipe conduit.

Figure 1C

[0017] It is a schematic diagram of an ultrasonic cavitation sensor according to another embodiment of the present disclosure, viewed along the axial flow direction of a pipe conduit associated with the cavitation sensor, in which there are no cavitation bubbles in the liquid flowing through the pump conduit.

Figure 1D

[0018] It is a schematic diagram similar to FIG. 1C in which there are cavitation bubbles in the liquid flowing through the pipe conduit.

Figure 2

[0019] It is a perspective view of an ultrasonic cavitation sensor module according to an embodiment of the present disclosure.

Figure 3

[0020] It is a side view of the cavitation sensor module shown in FIG. 2.

Figure 4

[0021] It is another perspective view of the cavitation sensor module shown in FIG. 2 with the upper cover of the enclosure of the cavitation sensor module removed.

Figure 5

[0022] It is a further perspective view of the cavitation sensor module shown in FIG. 2 with the entire enclosure of the cavitation sensor module removed.

Figure 6

[0023] It is a view of the cavitation sensor module shown in FIG. 5 with the cover removed, seen along the axial flow direction of the pipe segment of the cavitation sensor module.

Figure 7

[0024] It is an exploded perspective view of the transducer plug of the cavitation sensor module shown in FIG. 2.

Figure 8

[0025] It is a cross-sectional perspective view of the transducer plug shown in FIG. 7.

Figure 9

[0026] It is a schematic block diagram of the electronic controller substrate assembly of the cavitation sensor module shown in FIG. 2.

Figure 10

[0027] It is a perspective view of an ultrasonic cavitation sensor device according to another embodiment of the present disclosure.

Figure 11

[0028] It is a perspective view of the control unit of the ultrasonic cavitation sensor device shown in FIG. 10, and the front panel of the control unit has been removed to reveal the internal components of the control unit.

Figure 12

[0029] It is a cross-sectional perspective view of the pipe segment and the ultrasonic transducer system of the ultrasonic cavitation sensor device shown in FIG. 10.

Figure 13

[0030] FIGS. 13A through 13C are perspective views showing various types of pipe segments that can be used in an ultrasonic cavitation sensor device.

Figure 14

[0031] A perspective view of an ultrasonic transducer plug of an ultrasonic cavitation sensor device.

Figure 15

[0032] A cross-sectional view of the ultrasonic transducer plug shown in FIG. 14.

Figure 16

[0033] A perspective view of a pump formed according to a modification of the present disclosure, and the ultrasonic cavitation sensor device of the present disclosure is associated with the housing of the pump.

Figure 17

[0034] A partial cross-sectional side view of the pump and transducer portion of the ultrasonic cavitation sensor device shown in FIG. 16.

Figure 18

[0035] A perspective view of a valve formed according to a modification of the present disclosure, and the ultrasonic cavitation sensor device of the present disclosure is associated with the housing of the valve.

Figure 19

[0036] An axial cross-sectional view of the valve and the ultrasonic cavitation sensor device shown in FIG. 18.

Figure 20

[0037] A perspective view of a clamp-on ultrasonic cavitation sensor module according to a further embodiment of the present disclosure connected to a pipe segment.

Figure 21

[0038] A cross-sectional view of the clamp-on module and the pipe segment shown in FIG. 20.

Figure 22

[0039] A cross-sectional view of the ultrasonic transducer plug of the clamp-on module shown in FIG. 20.

Figure 23

[0040] A perspective view showing an ultrasonic cavitation sensor configuration using a transducer joined to a flow reducer fitting according to another embodiment of the present disclosure.

Figure 24

[0041] It is an exploded perspective view of the ultrasonic cavitation sensor configuration shown in FIG. 23.

Figure 25

[0042] It is a cross-sectional view of the ultrasonic cavitation sensor configuration shown in FIG. 23.

Figure 26A

[0043] It is a diagram showing a user interface display screen of an ultrasonic cavitation sensor device in which there are no cavitation bubbles in the liquid monitored by the device.

Figure 26B

[0044] It is a diagram similar to FIG. 26A, in which cavitation bubbles are present in the liquid monitored by the device.

Embodiments for Carrying Out the Invention

[0016]

[0045] Figures 1A and 1B schematically show a configuration for directly detecting cavitation bubbles by ultrasonic waves before the cavitation bubbles collapse on the surface. In both figures, the liquid flows through the conduit 1 of the pipe 2 in the axial direction of the pipe conduit, that is, in a direction perpendicular to the plane of the drawing. On one side of the pipe 2, a first transducer plug 4 having a first ultrasonic transducer 5 that extends through the wall of the pipe and is in acoustic communication with the liquid flowing through the pipe is installed. On the opposite side of the pipe 2, a second transducer plug 6 having a second ultrasonic transducer 7 that extends through the pipe wall and is in acoustic communication with the liquid flowing through the pipe conduit 1 is installed. As can be seen, the second ultrasonic transducer 7 faces the first ultrasonic transducer 5 along a lateral direction perpendicular to the axial direction of the pipe conduit 1 with the liquid flowing through the pipe conduit 1 in between. The first ultrasonic transducer 5 may be driven to transmit an ultrasonic signal in the form of a series of waves that propagate through the liquid flowing in the pipe conduit 1 towards the second ultrasonic transducer 7. The second ultrasonic transducer 7 is arranged to receive the ultrasonic signal transmitted by the first ultrasonic transducer 5 and is configured to generate an electronic cavitation detection signal representing the intensity of the ultrasonic signal received from the first ultrasonic transducer 5. For example, the pair of first and second ultrasonic transducers 5, 7 can be piezoelectric transducers operating in the ultrasonic frequency range.

[0017]

[0046] As shown in FIG. 1A, when the liquid flowing through the pipe conduit 1 does not have cavitation bubbles that obstruct the ultrasonic signal as the ultrasonic signal travels across the liquid in the pipe conduit 1, the cavitation detection signal generated by the second ultrasonic transducer 7 has a relatively high amplitude. However, as shown in FIG. 1B, when one or more cavitation bubbles are present in the flowing liquid, the ultrasonic signal is attenuated more greatly than in FIG. 1A, the energy received by the second ultrasonic transducer 7 is reduced, and the cavitation detection signal generated by the second ultrasonic transducer 7 has a smaller amplitude compared to the non-cavitation state of FIG. 1A. The intensity of the cavitation detection signal is a relative indicator of the size and / or number of cavitation bubbles present between the first ultrasonic transducer 5 and the second ultrasonic transducer 7.

[0018]

[0047] As will be described in detail below, an electronic controller and associated circuitry connected to the ultrasonic transducers 5, 7 may be configured to execute stored programming instructions to drive the first ultrasonic transducer 5, process the cavitation detection signal generated by the second ultrasonic transducer 7 to establish a cavitation measurement signal, and compare the cavitation measurement signal to a predetermined cavitation threshold. The controller may be programmed and configured such that an alarm is issued by the controller when the amplitude of the cavitation measurement signal drops below the cavitation threshold. The intensity of the ultrasonic signal generated by the first ultrasonic transducer 5 and the gain applied to the cavitation detection signal generated by the second ultrasonic transducer 7 when the ultrasonic signal is received may be controlled and adjusted by the controller. The number of bubbles or the accumulation of cavitation present in the flowing liquid may be calculated by the controller to provide additional information to the user.

[0019]

[0048] FIGS. 1C and 1D schematically show a modified configuration for direct ultrasonic detection of cavitation bubbles prior to the collapse of cavitation bubbles on the inner surface of the liquid conduit 1, which operates using the retroreflection of ultrasonic signals, also referred to as the "pulse echo" mode of operation. In contrast to the configuration shown in FIGS. 1A and 1B, the configuration of FIGS. 1C and 1D has a single ultrasonic transducer 5 that operates as both a transmitter and a receiver. The ultrasonic transducer 5 may be driven to transmit an ultrasonic signal that propagates through the liquid flowing within the liquid conduit 1 towards the opposing inner wall surface 3 of the conduit 1, and is arranged to receive the ultrasonic signal after the ultrasonic signal is retroreflected by the surface 3 and returns towards the ultrasonic transducer 5. The ultrasonic transducer 5 is configured to generate an electronic cavitation detection signal representing the intensity of the received ultrasonic signal. In the "pulse echo" configuration, the electronic controller and associated circuitry are connected to the ultrasonic transducer 5 and execute stored programming instructions to drive the ultrasonic transducer 5, and may be configured to process the cavitation detection signal generated by the ultrasonic transducer 5 in a manner similar to that described above with respect to FIGS. 1A and 1B and the second ultrasonic transducer 7.

[0020]

[0049] FIGS. 2-9 show a formed cavitation sensor module 10 according to an exemplary embodiment of the present disclosure. The cavitation sensor module 10 is intended to be installed in a pipe system (not shown) for conveying a liquid flow. For example, the cavitation sensor module 10 may be installed in industrial and structural hydraulic systems, liquid cooling systems such as those used in computer server farms, potable and wastewater systems, mining and agricultural liquid flow systems, and any liquid pump system where there is a potential for cavitation damage.

[0021]

[0050] The cavitation sensor module 10 can include a pipe segment 12, one or more first transducer plugs 14 each having a first ultrasonic transducer 15, one or more second transducer plugs 16 each having a second ultrasonic transducer 17 paired with a corresponding first ultrasonic transducer 15, and a controller circuit board assembly 18 connected to each first ultrasonic transducer 15 and each second ultrasonic transducer 17. In FIGS. 5 and 6, the connection wiring 19 is shown for connecting only a pair of ultrasonic transducers 15, 17 to the controller circuit board assembly 18, and the connection wiring for additional ultrasonic transducers 15, 17 is not shown for clarity. However, if additional ultrasonic transducers are used by the sensor module 10, the additional ultrasonic transducers are also connected to the controller circuit board assembly 18. The cavitation sensor module 10 can further include an enclosure 20 for protecting the first and second transducer plugs 14, 16 and the controller circuit board assembly 18 and for fixing the transducer plugs and the controller circuit board assembly to the pipe segment 12.

[0022]

[0051] As best seen in FIG. 5, the pipe segment 12 may be a straight length of metal or plastic pipe that defines a liquid flow conduit 30 through which liquid flows. The pipe segment 12 may include fittings 32 at both ends thereof for connecting the pipe segment 12 to the pipes of the liquid flow system in which the cavitation sensor module 10 is installed. For example, the fitting 32 may be a standard pipe fitting each having a female threaded portion 34 for mating with the system pipe and an external flat portion 36 for facilitating the application of torque to the pipe segment 12. The configuration of the fitting 32 may be selected to conform to the pipe specifications of the liquid flow system in which the cavitation sensor module 10 is installed. The pipe segment 12 may further include a plurality of ports 38 that extend radially through the wall of the pipe segment, for example through the wall of the pipe segment, for receiving and positioning the transducer plugs 14 and 16. Of course, the pipe segment 12 may be other than a straight segment, i.e., the liquid flow conduit 30 may be bent to change the flow direction.

[0023]

[0052] Here, for the description of the transducer plugs 14, 16 according to an embodiment of the present disclosure, specifically refer to FIGS. 7 and 8. Each transducer plug 14, 16 can include a shell 40 sized to slidably fit within a corresponding port 38 within the pipe segment 12. The shell 40 can hold the associated ultrasonic transducer 15 or 17 near its inner end 41 and defines a passage 42 through which wiring 19 can pass to connect the ultrasonic transducer to the controller circuit board assembly 18 by an electrical connector 43. The shell 40 can be made of metal (e.g., stainless steel) or plastic. The ultrasonic transducer 15 or 17 may be fitted into an insulating carrier 44 and mounted within the shell 40. The transducer plug shell 40 and its corresponding port 38 may be cylindrical as shown in the drawings or non-cylindrical. The use of the transducer plugs 14, 16 that slidably fit within the corresponding ports 38 within the pipe segment 12 facilitates efficient repair or replacement of the associated ultrasonic transducers 15, 17 in the event of a failure of the ultrasonic transducer.

[0024]

[0053] The ultrasonic transducers 15, 17 may be piezoelectric transducer elements. As a non-limiting example, the ultrasonic transducers 15, 17 may be made of any of several materials suitable for generating ultrasonic signals, such as lead zirconate titanate (PZT), lead metaniobate, quartz, or other piezoelectric materials. Ceramic transducer elements made of PZT supplied by Piezo Kinetics Inc. (PKI) or APC International may be used to practice the present disclosure. A ceramic transducer element that is considered suitable for a prototype of the cavitation sensor module 10 is a PZT disk with an outer diameter of 10.2 mm and a thickness of 1 mm sold by APC International under part number 973. The ultrasonic transducers 15, 17 may be disk-shaped as shown in FIGS. 7 and 8, or may be rectangular or square plate-shaped. The insulating carrier 44 electrically insulates between the ultrasonic transducers 15, 17 and the material of the plug shell 40.

[0025]

[0054] The transducer plugs 14 and 16 may incorporate ultrasonic transducers 15 and 17 of the same model or part number and be manufactured according to the same specifications in order to benefit from economies of scale in manufacturing. The present embodiment has four ports in the pipe, and thus two pairs of ultrasonic transducers 15, 17 can be used to redundantly measure cavitation.

[0026]

[0055] In a variant of the above-described embodiment, a single ultrasonic transducer may be used instead of each pair of ultrasonic transducers 15, 17. In that case, the single ultrasonic transducer transmits and receives ultrasonic signals in a "pulse-echo" mode of operation. Cavitation can be redundantly measured using multiple ultrasonic transducers operating in the pulse-echo mode.

[0027]

[0056] Figure 9 schematically shows an embodiment of the electronic controller board assembly 18. The controller board assembly 18 can include a programmable microcontroller 50, an internal programming header 51 connected to the microcontroller 50, one or more digital memory devices 52 connected to the microcontroller 50, a multiplexer 53 connected to the microcontroller 50, and an Ethernet port 55 and a serial port 56 that enable data communication between an external computing device 70 and the microcontroller 50. The internal programming header 51 enables programming of the microcontroller 50 in the factory and is not user-accessible.

[0028]

[0057] Power can be supplied to the components of the controller board assembly 18 via a power supply / voltage regulator circuit 58 and a brownout detection / watchdog timer circuit 60 connected to the microcontroller 50.

[0029]

[0058] The microcontroller 50 may be connected to transmit drive control signals to each of the first ultrasonic transducers 15 by a waveform generator circuit 62 and a transmission signal adjustment circuit 64. The intensity and timing of the ultrasonic signals generated by each of the first ultrasonic transducers 15 can be controlled and adjusted by the microcontroller 50 according to programming instructions executable by the microcontroller 50, such as firmware or software. A user interface may be provided to enable a user to input control parameters and settings that govern the characteristics of the ultrasonic signals generated by each of the first ultrasonic transducers 15. An external computing device 70, such as a personal computer, can function as such a user interface. Alternatively or additionally, a touch-sensitive display panel (not shown) incorporated on the enclosure 20 and connected for data communication with the microcontroller 50 may function as the user interface.

[0030]

[0059] The ultrasonic signal transmitted by each first ultrasonic transducer 15 through the liquid within the pipe segment 12 can be received by the corresponding second ultrasonic transducer 17. The cavitation detection signal generated by each second ultrasonic transducer 17 when receiving the ultrasonic signal can be processed by applying signal gain (i.e., scaling factor) and signal filtering in the circuit 66. The amount of gain and filtering characteristics applied to the cavitation detection signal from each second ultrasonic transducer 17 can be controlled and adjusted by the microcontroller 50 according to programming instructions executable by the microcontroller 50, such as firmware or software. As described above, the user can use a user interface (e.g., an external computing device 70) to input control parameters and settings that govern the gain and filtering characteristics of the cavitation detection signal generated by each second ultrasonic transducer 17.

[0031]

[0060] Each circuit 66 provides a cavitation measurement signal to the microcontroller 50. The cavitation measurement signal may be in the form of an analog voltage signal based on the cavitation detection signal from the associated second ultrasonic transducer 17, where signal noise is reduced by filtering and signal intensity is increased by gain / scaling. The cavitation measurement signal can be digitized by an analog-to-digital converter that may be provided as part of the microcontroller 50.

[0032]

[0061] The cavitation measurement signal is evaluated by the microcontroller 50 to determine whether cavitation bubbles are present in the liquid between the first ultrasonic transducer 15 and the paired second ultrasonic transducer 17 at a given measurement time. The microcontroller 50 may be configured to execute programming instructions, such as firmware or software stored in the memory, that cause the microcontroller to evaluate the amplitude of the cavitation measurement signal against one or more predetermined threshold values stored in the memory 52. The threshold values may be determined based on empirical tests. As a non-limiting example for illustration, the liquid in the conduit 30 where there are no cavitation bubbles between the first ultrasonic transducer 15 and the second ultrasonic transducer 17 can generate an output cavitation measurement signal of 3.0V, and the complete air in the conduit 30 between the first ultrasonic transducer 15 and the second ultrasonic transducer 17 can generate an output cavitation measurement signal of 1.0V. Thus, during operation, a cavitation measurement signal less than 3.0V will indicate the presence of at least one cavitation bubble, and there is a correlation between the cavitation measurement signal and the degree of cavitation present in the liquid. The closer the cavitation measurement signal is to 1.0V, the greater the level of cavitation in the liquid.

[0033]

[0062] The alarm threshold can be assigned corresponding to the level of cavitation bubbles that is known to cause damage to the system surface or components but has not yet been reached. The microcontroller 50 may be programmed to turn on the alarm when the cavitation measurement signal exceeds the alarm threshold. Continuing with the non-limiting example of the previous paragraph, an alarm threshold such as 2.0V may be assigned. When the cavitation measurement signal drops below the alarm threshold, the microcontroller 50 may activate an alarm device (e.g., an audible and / or visual alarm) to indicate the presence of potentially harmful cavitation so that corrective measures can be taken to prevent damage to the components or surface of the liquid flow system. The corrective measures may be implemented manually or automated. For example, the pump flow rate may be reduced manually in response to an audible and / or visual alarm or automatically in response to an alarm signal from the microcontroller 50.

[0034]

[0063] As described above, the microcontroller 50 can calculate the count of cavitation bubbles or the accumulation of cavitation present in the flowing liquid to provide additional information to the user. The microcontroller 50 may be programmed to detect the duration during which the cavitation measurement signal "goes low" (i.e., falls below a predetermined threshold). When the cavitation bubbles are relatively large, the detected duration can be used to estimate the total volume of the cavitation bubbles. The detected duration information can also be used by the microcontroller 50 to estimate the flow rate of the liquid flowing through the pipe segment 12. The microcontroller 50 may also be programmed to count the number of cavitation bubbles detected over time.

[0035]

[0064] The ability to control and adjust the characteristics of the ultrasonic signal transmitted through the liquid and the resulting cavitation measurement signal provided to the microcontroller 50, and the ability to assign or set the relevant thresholds and ranges used by the microcontroller 50 for the evaluation of the cavitation measurement signal, enables the cavitation sensor module 10 to be configured based on the specifications of the particular liquid flow system in which the cavitation sensor module is installed. Such specifications may include, but are not limited to, the type and physical characteristics of the flowing liquid, and the pumping flow rate or flow range.

[0036]

[0065] As further shown in FIG. 9, the controller board assembly 18 can include a digital output 68, an analog voltage output 72, and an analog current output 74 connected to the microcontroller 50. To enhance the functionality of the cavitation sensor module 10, additional sensors and transducers represented by block 76 may be connected to the microcontroller 50. Such additional sensors and transducers may include sensors and transducers for measuring or detecting pressure, temperature, flow rate, blockage, and foreign objects in the flow. For example, an optical sensor can be connected to the microcontroller 50 to detect foreign objects in the flow or other aspects of the flowing liquid. The controller board assembly 18 may also include an IO link transceiver 78 that enables data and signal communication with an external industrial network 80.

[0037]

[0066] The multiplexer 53 can be implemented between the microcontroller 50 and the various outputs 68, 72, 74, and 78. As a result, two pins of a single 4 - pin connector provide either (a) up to two digital outputs, or (b) up to two analog outputs (either voltage or current), or (c) an IO link output that is of the "data" type (not just a signal). The output type (a, b, or c) can be user - configurable.

[0038]

[0067] In an alternative implementation of the present disclosure, the programmable microcontroller 50 may be replaced by a microprocessor, a computer, a field programmable gate array (FPGA), or an electronic device that only includes hardware without involvement of firmware or software.

[0039]

[0068] As shown in FIGS. 2-4, the enclosure 20 may surround the transducer plugs 14, 16 and the controller circuit board assembly 18 and be configured to protect them from environmental contaminants. For example, the enclosure 20 may be sealed to prevent liquid from entering and damaging the transducer plugs 14, 16 and the controller circuit board assembly 18. The enclosure 20 includes a central component 22A dimensioned to receive the controller circuit board assembly 18 and a first radial portion of the pipe segment 12, a cover component 22B removably attached to the central component 22A and dimensioned to cover the controller circuit board assembly 18, and a fixing component 22C removably attached to the central component 22A and dimensioned to receive a second radial portion of the pipe segment 12 that faces the first radial portion of the pipe segment 12 and fix the enclosure 20 onto the pipe segment. The cover component 22B can be removably attached to the central component 22A by screw fasteners (not shown) disposed in a plurality of aligned fastener holes 24 in the cover component 22B and the central component 22A. The fixing component 22C can be removably attached to the central component 22A by threaded fasteners (not shown) disposed in a plurality of aligned fastener holes 26 in the fixing component 22C and the central component 22A. As can be seen from the figure, the enclosure 20 may be configured such that the enclosure does not surround the joint 32 of the pipe segment 12, thereby enabling access to the joint when the cavitation sensor module 10 is installed in the pipe system.

[0040]

[0069] As can be understood, the multi-piece configuration of the enclosure 20 according to the present disclosure enables the pipe segment 12 with the transducer plugs 14 and 16 to be installed in the pipe system before the other components of the cavitation sensor module 10 are installed. After the pipe segment 12 having the transducer plugs 14 and 16 is installed in the pipe system, the enclosure 20 including the controller circuit board assembly 18 may be attached to the pipe segment 12, and the connection wiring 19 from the ultrasonic transducers 15, 17 may be connected to the controller circuit board assembly 18 by inserting the electrical connector 43 into the corresponding connection socket of the controller circuit board assembly. The multi-piece configuration of the enclosure 20 also enables the cavitation sensor module 10, the minus pipe segment 12, and the transducer plugs 14 and 16 to be easily removed from the pipe system.

[0041]

[0070] In the above-described embodiments, the control electronic device is attached to a housing, such as a pipe segment 12 or a pump housing. FIGS. 10 to 17 show an ultrasonic cavitation sensor device 110 according to another embodiment of the present disclosure, in which the control electronic device of the device is located away from a housing having a liquid flow conduit. The ultrasonic cavitation sensor device 110 generally includes a control unit 111, a housing 112 (e.g., a pipe segment or a pump housing), one or more first transducer plugs 14 each having a first ultrasonic transducer 15, one or more second transducer plugs 16 each having a second ultrasonic transducer 17 paired with the corresponding first ultrasonic transducer 15, and a controller circuit board assembly 118 located away from the housing 112 within an enclosure 120 of the control unit 111. The circuit board assembly 118 can be connected to each first ultrasonic transducer 15 and each second ultrasonic transducer 17 by a transducer cable 119. As seen in FIG. 11, the circuit board assembly 118 can include a coaxial power connector 59, an Ethernet port 55, and a plurality of cable connectors 67 for connecting the transducer cable 119 to the circuit board assembly 118.

[0042]

[0071] FIG. 12 shows a housing 112 embodied as a pipe segment having a liquid conduit 30 and a pair of female pipe fittings 32 each having a female threaded portion 34 for mating with a system pipe. Of course, other types of pipe segments may be used to embody the housing 112. For example, in FIG. 10, the housing 112 is embodied by a pipe segment having a pair of fittings 32 with male threads 34. Examples of general pipe segment configurations useful as the housing 112 are shown in FIGS. 13A - 13C. FIG. 13A shows a pipe segment having a "sanitary flange" connection fitting 32. FIG. 13B shows a pipe segment having a female NPT fitting 32 similar to the housing 112 of FIG. 12. FIG. 13C shows a pipe segment having a male NPT fitting 32 similar to the housing 112 of FIG. 10. The sizing of the pipe segment may be adapted to meet system requirements and standard sizes may be provided to fit nominal pipe sizes such as 1 inch, 1.5 inches, 2 inches, 2.5 inches, and 3 inches. Of course, larger or smaller sizes may be developed and the configuration of the fitting 32 follows design choices. Threaded ports 38 for receiving the transducer plugs 14 and 16 may be drilled and tapped through the wall of the housing 112 such that the transducer plugs are coaxially arranged across the fluid conduit 30 from each other. By using a standardized configuration for the transducer plugs 14 and 16 and the transducer ports 38, economies of scale and design simplicity are achieved.

[0043]

[0072] Figures 14 and 15 show another embodiment of the transducer plugs 14 and 16 according to the present disclosure. The plugs 14, 16 are sealed and highly modular. As can be seen, the plugs 14, 16 include a plug housing 82 that can be machined from either plastic or metal, a carrier plate 84 that can be formed from plastic, piezoelectric transducer elements 15, 17 supported by the carrier plate 84, and a sealed connector 86 having a pair of contact members 88 connected to the transducer elements 15, 17 by a pair of wires 89. In the illustrated embodiment, the connector 86 is fixed to a circular mounting plate 90 by a nut 92 and fluid-sealed with an O-ring 94. The mounting plate 90 may be fixedly held within the plug housing 82 by an adhesive potting 96. As can be understood, the transducer cable 119 can be removably connected at one end to the connector 86 of the transducer plugs 14, 16 and at the opposite end to a cable connector 67 on the circuit board assembly 118. The plug housing 82 includes a male threaded portion 83 designed to mate with a female threaded port 38 within the housing 112 for easy attachment and removal of the transducer plugs 14, 16.

[0044]

[0073] As shown in FIGS. 16 and 17, the ultrasonic cavitation sensor device 110 may be modified for installation on the pump housing 212 of the centrifugal pump 200, and the pump housing 212 serves in place of the pipe segment 112. The pump housing 212 includes an outlet liquid conduit 230 and a plurality of ports 238 extending through the wall of the pump housing for receiving and positioning the transducer plugs 14 and 16. Since the transducer plugs 14, 16 are threaded and have an O-ring seal for high-pressure fluid sealing, the outlet of the pump housing 212 can be drilled and threaded on a common central axis to form the ports 238, and the transducer plugs 14, 16 can be threaded into the ports 238.

[0045]

[0074] As shown in FIGS. 18 and 19, the ultrasonic cavitation sensor device 110 may be modified for installation on the valve housing 312 of the liquid flow valve 300, and the valve housing 312 serves instead of the pipe segment 112. The valve housing 312 includes a liquid conduit 330 and a plurality of ports 338 that extend through the wall of the valve housing for receiving and positioning the transducer plugs 14 and 16. The transducer plugs 14, 16 are threaded and have O-ring seals for high-pressure fluid sealing. The valve housing 312 may be drilled and threaded on a common central axis to form the ports 338, and the transducer plugs 14, 16 may be threaded into the ports 338.

[0046]

[0075] A "clamp-on" variant of the present disclosure is shown in FIGS. 20-22. In the clamp-on variant, the ultrasonic transducers 15, 17 can be installed on a clamp body 400 configured to be clamped onto an existing pipe segment or pipe 412, or another housing within an existing liquid flow system having a liquid flow conduit 430. The clamp-on variant can be used in situations where non-invasive installation is desired, i.e., situations where it is not practical, safe, or possible to access the liquid flow conduit and drill and tap an existing housing to install the transducer plugs 14, 16. The clamp-on variant is non-invasive because the transducer plugs 14, 16 do not protrude into the liquid conduit 430 through which the liquid flows.

[0047]

[0076] Figures 20 and 21 show a simple example for clamping a cylindrical pipe, which comprises a clamp body 400 having a pair of arcuate brackets 401 and 402 designed to releasably fit together and clamp around the cylindrical pipe 412 within the outer diameter range. In the illustrated embodiment, bracket 401 includes a first flange 403 having a through opening 404 and a second flange 405 having a through fastener hole 409, and bracket 402 includes a first flange 407 bent to define a latch sized to be removably received through opening 404 and a second flange 408 having a through fastener hole 406. A bolt 410 is disposed through the aligned fastener holes 406, 409 and fixed with a nut 411 to adjustably clamp the clamp body 400 onto the pipe 412. Each bracket 401, 402 can include a female threaded port 38 for receiving and positioning the transducer plugs 14, 16 such that when brackets 401, 402 are clamped together, the corresponding transducers 15, 17 are axially aligned with each other across the liquid conduit 430 of the pipe 412. Although simple clamp brackets are shown in Figures 20 and 21, other clamp configurations are possible, including but not limited to linear sliding rails or spring-loaded transducer housings. A transducer connection cable (not shown) may be provided to connect the transducer plugs 14, 16 to the control unit 111 as described above.

[0048]

[0077] In a modification of the clamp-on, the ultrasonic signal from each first ultrasonic transducer 15 must travel through the wall of the housing 412 twice for the signal to reach the paired second ultrasonic transducers 17. Therefore, a modification that minimizes the signal attenuation effect of the housing wall may be advantageous. A good coupling of the transducers 15, 17 to the outer wall surface of the housing 412 is important. For this reason, as best seen in FIG. 22, each transducer plug 14, 16 can include a compliant surface pad 87 on the end face of the plug housing 82. The compliant surface pad 87 may be made of an elastomeric material so as to conform to the contour of the outer wall surface of the housing 412 when the clamp body 400 is tightened onto the housing 412. An ultrasonic joint containing a liquid or gel may be provided in association with each of the transducer plugs 14, 16 to assist in the propagation of ultrasonic energy between each ultrasonic transducer 15, 17 and the existing housing 412 to which the transducer is clamped. The intensity of the transmitted ultrasonic signal and the gain applied to the received cavitation detection signal may be increased to compensate for the ultrasonic signal attenuation caused by the housing wall.

[0049]

[0078] Alternative joined or bonded embodiments of the present disclosure are shown in FIGS. 23-25. In many cases, there are physical space or weight constraints for the application, and the use of transducer plugs 14, 16 is not feasible. Or, in some cases, it may not be desirable to have a transducer plug configuration with a port 38 that is invasive and can disrupt the otherwise smooth inner surface of a liquid conduit within a pipe, fitting, or other system component housing. In these cases, the ultrasonic transducer system 500 can be joined to the outer surface of the component housing 512. For example, in the drawings, the housing 512 is embodied as a reducer fitting where cavitation can be generated at the inner diameter transition of the liquid conduit 530. The attachment area may be too small for an invasive transducer plug assembly, and if a transducer plug is installed, the transducer plug itself may cause undesirable cavitation. In the joined alternative, the transducer assemblies 514 and 516 may be attached outside the fitting 512. Each transducer assembly 514, 516 can include a carrier plate 84, which can be formed of plastic, piezoelectric transducer elements 15, 17 supported by and joined to the carrier plate 84, and a pair of wires 89 connected to the transducer elements 15, 17. A suitable attachment location can be prepared by machining a counterbore or flat surface 513 on the outer surface of the fitting 512. The carrier plate 84 of each transducer assembly 514, 516 can be joined to the surface 513 using a suitable adhesive or bonding agent. As described above, axial alignment of the paired transducer elements 15 and 17 is desirable. The wires 89 from each transducer element 15, 17 may be supplied to a connection cable (not shown) that connects to a corresponding cable connector 67 on the control unit 111.

[0050]

[0079] As can be appreciated, each embodiment described herein as using paired transducers 15, 17 can be modified to operate using a single transducer operating in a pulse-echo configuration.

[0051]

[0080] Here, to describe an optional user interface display screen 600 of the ultrasonic cavitation sensor device 110, reference is made to FIGS. 26A and 26B. The screen 600 can be displayed on an external computing device 70, such as a personal computer, and / or on a touch-sensitive display panel connected for data communication with the microcontroller 50. The sensor device can operate in a stand-alone configuration and provide digital and / or analog output signals to a connected device, so a user interface is not necessary for the use of the cavitation sensor device 110. However, a user interface may be provided and used to set the sensitivity parameters and general setup parameters of the sensor device 110.

[0052]

[0081] The user interface screen 600 enables a user to monitor the functions of the sensor device 110 and set the operating parameters of the sensor device 110. FIG. 26A shows the display screen 600 during operation of the sensor device 110 when no cavitation bubbles are present, and FIG. 26B shows the display screen 600 during operation of the sensor device 110 when four sets of cavitation bubbles are present. FIGS. 26A and 26B represent snapshots of the screen 600 during operation of the sensor device 110, and certain portions of the display screen 600 are dynamic and change as the liquid flow state monitored by the sensor device 110 changes.

[0053]

[0082] The screen 600 may include a signal strip chart panel 602, an averaged signal strip chart panel 604, an averaging slider tool 605, a tuning slider tool 606, a signal data panel 608, a status text box 610, and a cavitation alarm setup panel 611. The screen 600 may include additional interface items intended to be used by factory setup technicians and service technicians as opposed to the end users of the sensor device 110. These additional items of the screen 600 may include a communication configuration panel 614, tuning control panels 615 and 616, and a recording capture panel 618. It is conceivable to provide a limited version of the screen 600 that does not include the additional items 614, 615, 616, and 618 for end users and an extended version of the screen 600 that includes the additional items 614, 615, 616, and 618 for factory and service technicians.

[0054]

[0083] The signal strip chart panel 602 has a strip chart recorder 620 that shows the instantaneous intensity of the received ultrasonic signal as a function of time and may include a slider tool 622 for setting the number of points on the X-axis (time axis) of the strip chart recorder 620. The signal intensity range is shown on the left side of the panel (0 - 100%). If the received signal is 100%, it indicates that there are no cavitation bubbles in the liquid between the ultrasonic transmitter 15 and the ultrasonic receiver 17. If the received signal is 0%, it indicates that there is sufficient cavitation bubble formation to block the path of the ultrasonic signal from the transmitter to the receiver. Values between 0% and 100% indicate the relative size or volume of the cavitation bubbles present in the path of the ultrasonic signal from the transmitter to the receiver. The received signal intensity is inversely proportional to the size of the cavitation bubbles in the path of the ultrasonic signal from the transmitter to the receiver.

[0055]

[0084] The averaged signal strip chart panel 604 is similar to the signal strip chart panel 602. The averaged signal strip chart panel 604 has a strip chart recorder 624 that shows a smoothed average of the signal intensity as a function of time, rather than the instantaneous signal intensity as shown in the strip chart recorder 620. This difference is more readily apparent in FIG. 26B than in FIG. 26A. The averaged signal strip chart panel 604 can include a slider tool 626 for setting the number of points on the X-axis (time axis) of the strip chart recorder 624. The averaging slider tool 605 sets the time interval over which the signal intensity is averaged in the strip chart recorder 624.

[0056]

[0085] The tuning slider tool 606 sets the time between tuning events at which the resonant frequency of the first ultrasonic transducer 15 is found for transmitting at maximum signal intensity. For example, a tuning event may include a frequency sweep of the first ultrasonic transducer 15 to find the resonant frequency.

[0057]

[0086] The signal data panel 608 displays instantaneous measurement data of the ultrasonic transducers 15, 17, such as received signal intensity, transmitter frequency, peak voltage of the receiving transducer 17, and other measurement data. The received signal intensity shown in the signal data panel 608 is the same as the instantaneous signal intensity represented in the strip chart recorder 620 at the right end (right vertical axis) of the strip chart recorder 620.

[0058]

[0087] The status text box 610 displays the data recorded by the sensor device 110.

[0059]

[0088] The cavitation alarm setup panel 611 includes an interface tool that enables a user to establish one or more alarm conditions for triggering the generation of a cavitation alarm signal based on the characteristics of the cavitation measurement signal. The alarm condition may include a cavitation occurrence condition that is satisfied when the intensity of the cavitation measurement signal falls below a cavitation alarm setpoint. For example, through observation by the user, if it is determined that potential system damage may occur when the intensity of the cavitation measurement signal drops below 10%, the cavitation alarm setpoint may be set to 10% as shown in FIGS. 26A and 26B. The cavitation alarm setup panel 611 may include a setpoint slider tool 628, a setpoint scroll 630, and / or other user interface input tools through which a user can input a variable user input for establishing the cavitation alarm setpoint.

[0060]

[0089] The microcontroller 50 may be programmed to register a cavitation error count corresponding to the number of consecutive times the cavitation generation condition is satisfied, and the alarm condition may further include a cavitation error count condition that is satisfied when the cavitation error count is equal to a cavitation error count setting specified by the user. As can be understood, the error count setting may be set to a value high enough to eliminate nuisance alarms. For example, in FIGS. 26A and 26B, the cavitation error count setting is set to 5 such that five consecutive events in which the cavitation generation condition is satisfied (i.e., the cavitation measurement signal falls below the cavitation alarm set point) are required to trigger an output alarm. In one embodiment, the error count setting can be set to any integer value from 1 to 1000, although other ranges can also be provided for the error count setting. The cavitation alarm setup panel 611 may include an error count scroll 632 and / or other user interface input tools, whereby the user may enter variable user input to establish the error count setting.

[0061]

[0090] The communication configuration panel 614 includes switches used to facilitate communication between the external computing device 70 and the ultrasonic transducers 15, 17 for debugging and development purposes. The switch 634 may control the Transmission Control Protocol (TCP) to selectively enable the external computing device 70 as a host via an Ethernet connection. The switch 636 changes the operating mode of the ultrasonic transducer between a pulse transmission mode and a continuous transmission mode. The switch 638 pauses the tuning sweep for debugging. The switch 640 turns the tuning on and off (when the tuning is off, the ultrasonic transducer operates at a static frequency).

[0062]

[0091] Tuning control panels 615 and 616 allow the technician to enter other settings for development and debugging purposes. Tuning control panel 615 allows the user to change ultrasonic transducer pulses and tuning settings. Tuning control panel 616 allows the user to adjust the tuning set point (i.e., the allowable level of the maximum reading value). This panel would not be available in the commercial version.

[0063]

[0092] Recording capture panel 618 allows the user to set a file name for recording data, set a tuning range, and enable and disable the capture of status box 642.

[0064]

[0093] As described above, communication configuration panel 514, tuning control panels 615 and 616, and recording capture panel 618 are intended for use by factory and service technicians and can be omitted from the commercially available user interface screen 600 available to end users.

[0065]

[0094] Figure 26A shows the user interface screen 600 when there are no cavitation bubbles present. As can be seen in strip chart recorders 620 and 624, the intensity of the cavitation measurement signal remains very high. In contrast, Figure 26B shows the user interface screen 600 when some cavitation bubbles are present. Strip chart recorders 620 and 624 show at least four large cavitation events where the instantaneous intensity of the cavitation measurement signal drops to nearly 0%. The traces of strip chart recorders 620 and 624 move from right to left such that the current cavitation measurement signal intensity is on the right axis (right end) of each chart.

[0066]

[0095] The numerical intensity value of the current instantaneous signal is displayed in the upper text box within the signal data panel 608. In this example, the signal intensity is 0.0%. If the signal intensity falls below the cavitation alarm set point and meets the cavitation error count setting input by the user in the cavitation alarm setup panel 611, the program instructions executed by the microcontroller 50 cause the microcontroller to generate a cavitation alarm signal. The cavitation alarm signal may be transmitted directly or via the industrial network 80 to an external control device connected to the circuit board assembly 118. For example, the cavitation alarm signal may be transmitted to a flow valve controller and / or a pump controller to automatically reduce or stop the liquid flow through the conduit 130 in response to the alarm signal in order to prevent cavitation damage before it begins. Alternatively or additionally, the cavitation alarm signal may be transmitted to trigger audible and / or visual alarm devices to warn personnel of cavitation. If a cavitation alarm signal is generated, a visual indication of the alarm signal may be provided on the user interface screen 600, such as changing the color of the upper text box within the signal data panel 608 to red to indicate the alarm status.

[0067]

[0096] The cavitation sensor module 10 and the cavitation sensor device 110 of the present disclosure directly detect and measure cavitation vapor bubbles in a flowing liquid. This is different from the aforementioned indirect detection methods that detect cavitation artifacts such as noise, vibration, or pump behavior. As a result, cavitation bubbles are detected before they can be acoustically heard or visually seen, so damage to the equipment can be prevented. Further, cavitation can be quantified by measuring the size and / or number of the bubbles present. Cavitation may be detected at very low levels, and the detection logic can be adjusted or tuned to ignore cavitation below a set level where cavitation is merely an annoyance and does not cause damage. Unlike some prior art indirect cavitation sensors, the cavitation sensor module 10 and the cavitation sensor device 110 of the present disclosure are suitable for use in noisy environments. The cavitation sensor module 10 and the cavitation sensor device 110 are small and inexpensive to manufacture.

[0068]

[0097] The cavitation sensor of the present disclosure, and the methodology employed thereby, find useful applications in heavy industry to protect expensive pump systems from potential cavitation damage. Other applications include predictive maintenance, leak detection, and safety alarms.

[0069]

[0098] Although the present disclosure describes various exemplary embodiments, the detailed description is not intended to limit the scope of the present disclosure to the specific forms described. The present disclosure is intended to cover alternatives, modifications, and equivalents of the described embodiments that will be apparent to those skilled in the art.

Claims

Claim 1 An apparatus for detecting cavitation in a liquid flowing through a liquid conduit, the apparatus comprising: an ultrasonic transducer system including one or more ultrasonic transducers arranged to be in acoustic communication with the liquid flowing through the conduit; control electronics connected to the ultrasonic transducer system, the control electronics being configured to drive the ultrasonic transducer system to transmit an ultrasonic signal through the liquid flowing through the conduit, the ultrasonic transducer system receiving the ultrasonic signal and generating an electronic cavitation detection signal representative of the intensity of the ultrasonic signal received by the ultrasonic transducer system; the control electronics being further configured to process the cavitation detection signal to provide a cavitation measurement signal indicating whether the ultrasonic signal has interacted with one or more cavitation bubbles in the liquid flowing through the conduit, evaluate the cavitation measurement signal to determine whether one or more cavitation alarm conditions are satisfied, and output an alarm signal when each of the one or more cavitation alarm conditions is satisfied, an apparatus for detecting cavitation in a liquid flowing through a liquid conduit. Claim 2 The apparatus of claim 1, further comprising a housing having the conduit, each of the one or more ultrasonic transducers being attached to the housing. Claim 3 The apparatus of claim 1, wherein the one or more ultrasonic transducers of the ultrasonic transducer system include a first ultrasonic transducer and a second ultrasonic transducer opposite the first ultrasonic transducer across the conduit, the control electronics being configured to drive the first ultrasonic transducer to transmit the ultrasonic signal through the liquid flowing through the conduit, the second ultrasonic transducer receiving the ultrasonic signal and generating the electronic cavitation detection signal. Claim 4 The one or more ultrasonic transducers of the ultrasonic transducer system include a single ultrasonic transducer, and the control electronics are configured to drive the single ultrasonic transducer to transmit the ultrasonic signal through the liquid flowing through the conduit such that the ultrasonic signal is retroreflected by the housing to the single ultrasonic transducer, and the single ultrasonic transducer receives the ultrasonic signal and generates the electronic cavitation detection signal. The device according to claim 1.

5. The device according to claim 1, further comprising a user interface connected to the control electronics.

6. The device according to claim 5, wherein the user interface is configured to display a value representing the cavitation measurement signal and / or the instantaneous intensity of the cavitation measurement signal.

7. The device according to claim 5, wherein the control electronics have a cavitation alarm set point, and the one or more cavitation alarm conditions include a cavitation occurrence condition that is satisfied when the intensity of the cavitation measurement signal falls below the cavitation alarm set point.

8. The device according to claim 7, wherein the user interface is configured to receive a first variable user input for establishing the cavitation alarm set point.

9. The device according to claim 7, wherein the control electronics have a cavitation error count setting, and the control electronics are configured to register a cavitation error count corresponding to the number of consecutive times the cavitation occurrence condition is satisfied, and the one or more cavitation alarm conditions include a cavitation error count condition that is satisfied when the cavitation error count is equal to the cavitation error count setting.

10. The device according to claim 9, wherein the user interface is configured to receive a second variable user input for establishing the cavitation error count setting.

11. The device according to claim 1, wherein the control electronics are located away from the housing.

12. The device according to claim 1, wherein the control electronics are attached to the housing.

13. The housing of the apparatus according to claim 1 is selected from a group of housings consisting of a pipe segment, a pump housing, a valve housing, and a flow reducer.

14. A method for detecting cavitation in a liquid flowing through a conduit, the method comprising: placing a first ultrasonic transducer in acoustic communication with the liquid flowing through the conduit; placing a second ultrasonic transducer in acoustic communication with the liquid flowing through the conduit, the second ultrasonic transducer being opposite the first ultrasonic transducer across the conduit; driving the first ultrasonic transducer to transmit an ultrasonic signal through the liquid flowing through the conduit; receiving the ultrasonic signal by the second ultrasonic transducer; generating, by the second ultrasonic transducer, an electronic cavitation detection signal representing the intensity of the ultrasonic signal received by the second ultrasonic transducer; processing the cavitation detection signal to provide a cavitation measurement signal indicating whether the ultrasonic signal interacted with one or more cavitation bubbles in the liquid flowing through the conduit; evaluating the cavitation measurement signal to determine whether one or more cavitation alarm conditions are met; outputting an alarm signal when each of the one or more cavitation alarm conditions is met.

15. The method according to claim 14, further comprising displaying the cavitation measurement signal and / or a value representing the instantaneous intensity of the cavitation measurement signal.

16. The one or more cavitation alarm conditions include cavitation occurrence conditions, and the step of evaluating the cavitation measurement signal includes comparing the intensity of the cavitation measurement signal with a predetermined cavitation alarm set point and determining that the cavitation occurrence conditions are met when the intensity of the cavitation measurement signal is below the cavitation alarm set point. The method according to claim 15.

17. The one or more cavitation alarm conditions include a cavitation error count condition, and the step of evaluating the cavitation measurement signal includes registering a cavitation error count corresponding to the number of consecutive times the cavitation occurrence condition is satisfied, and determining that the cavitation error count condition is satisfied when the cavitation error count is equal to a predetermined cavitation error count setting. The apparatus according to claim 16, comprising:

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