Patent Publication Number: US-11028845-B2

Title: Cavitation avoidance system

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to pressure pumps for a wellbore and, more particularly (although not necessarily exclusively), to using boost pressure measurements to avoid cavitation in a multiple-pump wellbore system. 
     BACKGROUND 
     Pressure pumps may be used in wellbore treatments. For example, hydraulic fracturing (also known as “fracking” or “hydro-fracking”) may utilize a pressure pump to introduce or inject fluid at high pressures into a wellbore to create cracks or fractures in downhole rock formations. Due to the high-pressured and high-stressed nature of the pumping environment, pressure pump parts may undergo mechanical wear and require frequent replacement. Frequently changing parts may result in additional costs for the replacement parts and additional time due to the delays in operation while the replacement parts are installed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram depicting an example of a multiple-pump wellbore environment according to one aspect of the present disclosure. 
         FIG. 2  is a cross-sectional schematic diagram depicting an example of a pressure pump of the wellbore environment of  FIG. 1  according to one aspect of the present disclosure. 
         FIG. 3  is a block diagram depicting a manifold trailer of the wellbore environment of  FIG. 1  according to one aspect of the present disclosure. 
         FIG. 4  is a block diagram depicting a monitoring system of  FIG. 1  according to one aspect of the present disclosure. 
         FIG. 5  is a flow chart of an example of a process for determining a cavitation threshold according to one aspect of the present disclosure. 
         FIG. 6  is a flow chart of an example of a process for determining delays in the actuation of valves in a pressure pump of  FIG. 1  according to one aspect of the present disclosure. 
         FIG. 7  is a signal graph depicting an example of a signal generated by a position sensor of the monitoring system of  FIG. 4  according to one aspect of the present disclosure. 
         FIG. 8  is a signal graph depicting an example of another signal generated by a position sensor of the monitoring system of  FIG. 4  according to one aspect of the present disclosure. 
         FIG. 9  is a signal graph depicting an example of a signal generated by a strain gauge of the monitoring system of  FIG. 4  according to one aspect of the present disclosure. 
         FIG. 10  is a signal graph depicting actuation delays of a suction valve and a discharge valve of a pressure pump of  FIG. 1  according to one aspect of the present disclosure. 
         FIG. 11  is a signal graph depicting a signal generated by a boost pressure of the monitoring system of  FIG. 4  according to one aspect of the present disclosure. 
         FIG. 12  is a flow chart of an example of determining boost pressure of a pump at a point of cavitation according to one aspect of the present disclosure. 
         FIG. 13  is a plot graph depicting an example of a comparison of the actuation delays of  FIG. 10  for multiple pumps sections according to one aspect of the present disclosure. 
         FIG. 14  is a flow chart of an example of a process for avoiding cavitation in a pressure pump according to one aspect of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Certain aspects and examples of the present disclosure relate to correlating boost pressure of multiple pressure pumps with actuation delays of valves in the chamber to identify a threshold for cavitation in each of the pressure pumps. In some aspects, a monitoring system may rebalance the pump rates of the pumps in the spread to avoid cavitation in a pump having a boost pressure beyond the cavitation threshold. Cavitation may be present in a fluid chamber when pressure in the chamber fluctuate to create a vacuum that turns a portion of the fluid in the chamber into a vapor. Introducing vapor into the chamber may cause the chamber to be incompletely filled by the fluid traversing the pressure pump. The vapors may form small bubbles of gas that may collapse and transmit damaging shock waves through the fluid in the pressure pump. The boost pressure may correspond to the fluid pressure above atmospheric pressure in or near an inlet to the chamber. 
     In one example, a system may correlate strain in the chamber with the movement of the plunger to determine delays in actuation, or opening and closing, of the valves. The delays may correspond to the amount of fluid entering the chamber as the plunger regresses from the chamber. The system may compare and monitor the actuation delays across each of the chambers to determine a point at which cavitation is present in the chamber, and may identify the minimum boost pressure in a suction (or boost) manifold of the pressure pump at the point to determine a cavitation threshold for the pump. The cavitation threshold may correspond to a boost pressure in a chamber of the pressure pump that is close to, or below, the identified minimum boost pressure. 
     Boost pressure may be monitored in multiple pressure pumps and pump rate of a pressure pump having a boost pressure beyond a cavitation threshold may be automatically adjusted to avoid cavitation in the pump. To maintain a constant flow rate of fluid into and out of a manifold trailer fluidly coupled to the pressure pumps, the pressure pump may also adjust the pump rate of one or more other pressure pumps in an opposing direction (e.g., lower the pump rate of a second pump where the pump rate of a first pump is raised). A system may monitor the pressure pumps to determine if the pressure pump beyond the cavitation threshold is improving. For example, the system may monitor the pressure pump beyond the cavitation threshold to determine whether the boost pressure or valve actuation delays indicate less or no cavitation in the fluid chamber. The system may continue adjustments to the pump rates of the pressure pumps in the same direction subsequent to indications of an improvement. The system may reverse the adjustments to the pressure pumps subsequent to indications that the pressure pump beyond the cavitation threshold is not improving. 
     A system according to some aspects of the present disclosure may reduce or prevent cavitation in the pressure pumps of a wellbore environment in real-time during pumping operations in a wellbore. Cavitation in a pressure pump may cause significant damage to the pressure pump. The damage may result in costly repairs to components of the pressure pump and significant delays in pumping operations while such repairs are implemented. Identifying conditions for potential cavitation and adjusting pump rates to avoid cavitation in the pressure pumps may result in significant cost-savings in parts and labor. 
     These illustrative examples are provided to introduce the reader to the general subject matter discussed here and are not intended to limit the scope of the disclosed concepts. The following sections describe various additional aspects and examples with reference to the drawings in which like numerals indicate like elements, and directional descriptions are used to describe the illustrative examples but, like the illustrative examples, should not be used to limit the present disclosure. The various figures described below depict examples of implementations for the present disclosure, but should not be used to limit the present disclosure. 
     Various aspects of the present disclosure may be implemented in various environments. For example,  FIG. 1  is a cross-sectional schematic diagram depicting an example of a multiple-pump wellbore environment according to one aspect of the present disclosure. The wellbore environment includes pressure pumps  100 ,  102 ,  104 . Although three pumps  100 ,  102 ,  104  are shown in the wellbore environment of  FIG. 1 , two pressure pumps or more than three pressure pumps may be included without departing from the scope of the present disclosure. In some aspects, the pumps  100 ,  102 ,  104  may include any type of positive displacement pressure pump. The pumps  100 ,  102 ,  104  are each fluidly connected to a manifold trailer  106 . In some aspects, the pumps  100 ,  102 ,  104  may include one or more flow lines, or sets of fluid pipes, to allow fluid to flow from the manifold trailer  106  into the pumps  100 ,  102 ,  104  and to flow fluid out of the pumps  100 ,  102 ,  104  and into the manifold trailer  106 . In some aspects, the manifold trailer  106  may include a truck or trailer including one or more pump manifolds for receiving, organizing, or distributing wellbore servicing fluids during wellbore operations (e.g., fracturing operations). In some aspects, fluid from a first pump manifold of the manifold trailer  106  may enter the pumps  100 ,  102 ,  104  at a low pressure. The fluid may be pressurized in the pumps  100 ,  102 ,  104  and may be discharged from the pumps  100 ,  102 ,  104  into a second pump manifold of the manifold trailer  106  at a high pressure. 
     The fluid in the first pump manifold of the manifold trailer  106  may include fluid having various concentrations of chemicals to perform specific operations in the wellbore environment. For example, the fluid may include proppant or other additives for a fracturing operation. The fluid in the second pump manifold of the manifold trailer  106  may discharge the fluid having the proppant or additives to a wellhead  108  via a feed line extending from an outlet of the manifold trailer  106  to the wellhead  108 . The wellhead  108  may be positioned proximate to a surface of a wellbore  110 . The fluid discharged from the manifold trailer  106  may be pressurized by the pumps  100 ,  102 ,  104  and injected to generate fractures in subterranean formations  112  downhole and adjacent to the wellbore  110 . 
     A monitoring system may be included in the wellbore environment to control the operations of the pumps  100 ,  102 ,  104 . The monitoring system includes subsystems  114 ,  116 ,  118  for each of the pumps  100 ,  102 ,  104 , respectively. The subsystems  114 ,  116 ,  118  may monitor operational characteristics of the pumps  100 ,  102 ,  104 . In some aspects, each of the subsystems  114 ,  116 ,  118  may include monitoring devices to monitor, record, and communicate the operational characteristics of the pump. In additional and alternative aspects, the subsystems  114 ,  116 ,  118  may include a processing device or other processing means to perform adjustments to the pump. For example, the  114 ,  116 ,  118  may adjust a pump rate to change the flow rate of fluid through a pump  100 ,  102 ,  104  by modifying the speed at the crankshaft  208 , causing the plunger  214  to displace fluid in the chamber  206  of the pump  100 ,  102 ,  104 . In some aspects, the subsystems  114 ,  116 ,  118  may transmit information corresponding to the pumps  100 ,  102 ,  104  to a controller  120 . In some aspects, the controller  120  may include a processing device or other processing means for receiving and processing information from the pumps  100 ,  102 ,  104 , collectively. The controller  120  may transmit control signals to the pumps  100 ,  102 ,  104  to maintain a desired operation of a wellbore operation. For example, the controller  120  may determine that a flow rate of the pump  100  must be adjusted and transmit a signal to cause the subsystem  114  to adjust the pump rate of the pump  100  accordingly. Although separate subsystems  114 ,  116 ,  118  are described, the pumps  100 ,  102 ,  104  may be directly connected to a single controller device without departing from the scope of the present disclosure. 
       FIG. 2  is a cross-sectional schematic diagram depicting an example of the pump  100  of the wellbore environment of  FIG. 1  according to one aspect of the present disclosure. Although pump  100  is described in  FIG. 2 , pump  100  may represent any of the pumps  100 ,  102 ,  104  of  FIG. 1 . The pump  100  includes a power end  202  and a fluid end  204 . The power end  202  may be coupled to a motor, engine, or other prime mover for operation. The fluid end  204  includes at least one chamber  206  for receiving and discharging fluid flowing through the pump  100 . Although  FIG. 2  shows one chamber  206  in the pump  100 , the pump  100  may include any number of chambers  206  without departing from the scope of the present disclosure. 
     The pump  100  also includes a rotating assembly in the power end  202 . The rotating assembly includes a crankshaft  208 , a connecting rod  210 , a crosshead  212 , a plunger  214 , and related elements (e.g., pony rods, clamps, etc.). The crankshaft  208  may be mechanically connected to the plunger  214  in the chamber  206  of the pressure pump via the connecting rod  210  and the crosshead  212 . The crankshaft  208  may cause the plunger  214  for the chamber  206  to displace any fluid in the chamber  206  in response to the plunger moving within the chamber  206 . In some aspects, a pump  100  having multiple chambers may include a separate plunger for each chamber. Each plunger may be connected to the crankshaft of the plunger via a respective connecting rod and crosshead. The chamber  206  includes a suction valve  216  and a discharge valve  218  for absorbing fluid into the chamber  206  and discharging fluid from the chamber  206 , respectively. The fluid may be absorbed into and discharged from the chamber  206  in response to the plunger  214  moving. Based on the mechanical coupling of the crankshaft  208  to the plunger  214 , the movement of the plunger  214  may be directly related to the movement of the crankshaft  208 . 
     In some aspects, the suction valve  216  and the discharge valve  218  may be passive valves. As the plunger  214  operates in the chamber  206 , the plunger  214  may impart motion and pressure to the fluid by direct displacement. The suction valve  216  and the discharge valve  218  may open and close based on the displacement of the fluid in the chamber  206  by the plunger  214 . For example, during decompression of the pressure pump  100 , the suction valve  216  may be opened when the plunger  214  recesses to absorb fluid from outside of the chamber  206  into the chamber  206 . As the plunger  214  regresses from the chamber  206 , the plunger  214  may create a partial suction to open the suction valve  216  and allow fluid to enter the chamber  206 . In some aspects, the fluid may be absorbed into the chamber  206  from an intake manifold. Fluid already in the chamber  206  may move to fill the space where the plunger  214  was located in the chamber  206 . The discharge valve  218  may be closed during this process. 
     During compression of the pressure pump  100 , the discharge valve  218  may be opened as the plunger  214  moves forward or reenters the chamber  206 . As the plunger  214  moves further into the chamber  206 , the fluid may be pressurized. The suction valve  216  may be closed during this time to allow the pressure on the fluid to force the discharge valve  218  to open and discharge fluid from the chamber  206 . In some aspects, the discharge valve  218  may discharge the fluid into an output manifold. The loss of pressure inside the chamber  206  may allow the discharge valve  218  to close and the load cycle may restart. Together, the suction valve  216  and the discharge valve  218  may operate to provide the fluid flow in a desired direction. A measurable amount of pressure and stress may be present in the chamber  206  during this process, such as the stress resulting in strain to the chamber  206  or fluid end  204  of the pump  100 . 
     In some aspects, the pump  100  may include one or more measurement devices positioned on the pump  100  to obtain measurements of the pump  100 . For example, the pump  100  includes a position sensor  220 , a strain gauge  222 , and a pressure transducer  224  positioned on the pump  100 . The position sensor  220  is positioned on the power end  202  of the pump  100  to sense the position of the crankshaft  208  or another rotating component of the pump  100 . In some aspects, the position sensor  220  is positioned on an external surface of the power end  202  (e.g., on a surface of a crankcase for the crankshaft  208 ) to determine a position of the crankshaft  208 . The strain gauge  222  and the pressure transducer are positioned on the fluid end  204  of the pressure pump  100 . The strain gauge  222  is positioned on the fluid end  204  to measure the strain in the chamber  206 . In some aspects, the strain gauge  222  may be positioned on an external surface of the fluid end  204  (e.g., on an outer surface of the chamber  206 ) to measure strain in the chambers  206  without creating a puncturing or other opening in the fluid end  204 . The pressure transducer  224  is positioned on the fluid end  204  to measure pressure in the fluid end  204  of the pressure pump  100 . In some aspects, the pressure transducer  224  may be positioned at an inlet to the chamber  206 , proximate to the suction valve  216 . 
       FIG. 3  is a block diagram depicting an example of the manifold trailer  106  of the wellbore environment of  FIG. 1 . The pumps  100 ,  102 ,  104  are fluidly connected in parallel between an intake manifold  300  and an output manifold  302  of the manifold trailer  106 . The intake manifold  300  may include an inlet  304  connected to a common flow line fluidly connecting the pumps  100 ,  102 ,  104  to a fluid tank, blender, or other fluid source for providing fluid to the pressure pumps  100 ,  102 ,  104 . The output manifold  302  may include an outlet  306  connected to a common flow line fluidly connecting the pumps  100 ,  102 ,  104  to a fluid destination, such as the wellhead  108  of  FIG. 1 . The intake manifold  300  and the output manifold  302  include junctions A-F that allow fluid to flow from the fluid source to the pumps  100 ,  102 ,  104  and from the pumps  100 ,  102 ,  104  to the fluid destination. The junctions A, C, E correspond to the point where the flow of fluid from the fluid source travels through a common flow line and splits into two flows through separate pipes. The junctions B, D, F correspond to the point where the flow of fluid from the pumps  100 ,  102 ,  104  combines into a single flow through a common flow line to the fluid destination. 
     The flow rate in each pipe segment connecting the intake manifold  300  to the output manifold  302  is denoted by the variable F x y, where the subscript “X” represents the source junction and the subscript “Y” represents the destination junction. For example, the variable F AB  corresponds to a flow rate from the junction A to the junction B through the pump  100 . The variable F CD  corresponds to a flow rate from the junction C to the junction D through the pump  102 . The variable F EF  corresponds to a flow rate from the junction E to the junction F through the pump  104 . During a fracturing operation in the wellbore environment, the flow rate into the manifold trailer  106  and the flow rate out of the manifold trailer  106  may be the same, as denoted by the variable F 1 . The flow rates F AB , F CD , F EF  corresponding to the flow of fluid through the pumps  100 ,  102 ,  104 , respectively, denote that the respective flow rate into the pump  100 ,  102 ,  104  is the same as the flow rate coming out of the pump. This characterization of the flow rate through the pumps  100 ,  102 ,  104  may assume that each of the pumps  100 ,  102 ,  104  is operating at 100% efficiency. 
       FIG. 4  is a block diagram depicting the monitoring system of  FIG. 1  according to one aspect of the present disclosure. In some aspects, the monitoring system of  FIG. 4  may include a computing device  400  including one or more components that may be included in each of the subsystems  114 ,  116 ,  118  of  FIG. 1 . The subsystem  114  for the pump  100  includes the position sensor  220 , the strain gauge  222 , and the pressure transducer  224  communicatively coupled to the pump  100 . The subsystems  116 ,  118  may also include respective measurement devices for the pumps  102 ,  104 , respectively. 
     The position sensor  220  may include a magnetic pickup sensor capable of detecting ferrous metals in close proximity. In some aspects, the position sensor  220  may be positioned on the power end  202  of the pressure pump to determine the position of the crankshaft  208 . In some aspects, the position sensor  220  may be placed proximate to a path of the crosshead  212 . The path of the crosshead  212  may be directly related to a rotation of the crankshaft  208 . The position sensor  220  may sense the position of the crankshaft  208  based on the movement of the crosshead  212 . In other aspects, the position sensor  220  may be placed directly on a crankcase of the power end  202  as illustrated by position sensor  220  in  FIG. 2 . The position sensor  220  may determine a position of the crankshaft  208  by detecting a bolt pattern of the crankshaft  208  as the crankshaft  208  rotates during operation of the pump  100 . The position sensor  220  may generate a signal representing the position of the crankshaft  208  and transmit the signal to the computing device  400 . 
     The strain gauge  222  may be positioned on the fluid end  204  of the pump  100 . Non-limiting examples of types of strain gauges include electrical resistance strain gauges, semiconductor strain gauges, fiber optic strain gauges, micro-scale strain gauges, capacitive strain gauges, vibrating wire strain gauges, etc. In some aspects, a strain gauge  222  may be included for each chamber  206  of the pump  100  (e.g., where pump  100  is a multiple-chamber pressure pump) to determine strain in each of the chambers  206 , respectively. In some aspects, the strain gauge  222  may be positioned on an external surface of the fluid end  204  of the pump  100  in a position subject to strain in response to stress in the chamber  206 . For example, the strain gauge  222  may be positioned on a section of the fluid end  204  in a manner such that when the chamber  206  loads up, strain may be present at the location of the strain gauge  222 . This location may be determined based on engineering estimations, finite element analysis, or by some other analysis. The analysis may determine that strain in the chamber  206  may be directly over a plunger bore of the chamber  206  during load up. The strain gauge  222  may be placed on an external surface of the pump  100  in a location directly over the plunger bore corresponding to the chamber  206  as illustrated by strain gauge  222  in  FIG. 2  to measure strain in the chamber  206 . The strain gauge  222  may generate a signal representing strain in the chamber  206  and transmit the signal to the computing device  400 . 
     The pressure transducer  224  may be positioned on the fluid end  204  of the pump  100 . In some aspects, the pressure transducer  224  may include a boost gauge, a pressure gauge, a high-speed pressure sensor, or measurement device for measuring air pressure. In some aspects, the pressure transducer  224  may be positioned at an inlet to the chamber  206  to determine pressure in the intake manifold  300  of  FIG. 3  or in the chamber  206 . In additional and alternative aspects, the pressure transducer  224  may include a filter or other capabilities for processing differentials in the pressure measurements obtained by the pressure transducer  224 . For example, the pressure transducer  224  may include the envelope filter may be a low-enveloping filter that may generate a minimum or maximum suction pressure reading from a pressure signal generated by the pressure transducer  224 . In other aspects, the enveloping filter may be integral or accessible to the computing device 
     The computing device  400  may be coupled to the position sensor  220 , the strain gauge  222 , and the pressure transducer  24  to receive the respective signals from each. The computing device  400  includes a processor  402 , a memory  404 , and a display unit  412 . In some aspects, the processor  402 , the memory  404 , and the display unit  412  may be communicatively coupled by a bus. The processor  402  may execute instructions  406  for monitoring the pump  100 , determining cavitation conditions in the pump  100 , and controlling certain operations of the pump  100 . The instructions  406  may be stored in the memory  404  coupled to the processor  402  by the bus to allow the processor  402  to perform the operations. The processor  402  may include one processing device or multiple processing devices. Non-limiting examples of the processor  402  may include a Field-Programmable Gate Array (“FPGA”), an application-specific integrated circuit (“ASIC”), a microprocessor, etc. The non-volatile memory  404  may include any type of memory device that retains stored information when powered off. Non-limiting examples of the memory  404  may include electrically erasable and programmable read-only memory (“EEPROM”), a flash memory, or any other type of non-volatile memory. In some examples, at least some of the memory  404  may include a medium from which the processor  402  can read the instructions  406 . A computer-readable medium may include electronic, optical, magnetic, or other storage devices capable of providing the processor  402  with computer-readable instructions or other program code (e.g., instructions  406 ). Non-limiting examples of a computer-readable medium include (but are not limited to) magnetic disks(s), memory chip(s), ROM, random-access memory (“RAM”), an ASIC, a configured processor, optical storage, or any other medium from which a computer processor can read the instructions  406 . The instructions  406  may include processor-specific instructions generated by a compiler or an interpreter from code written in any suitable computer-programming language, including, for example, C, C++, C#, etc. 
     In some examples, at least some of the memory  404  may include a medium from which the processor  402  can read the instructions  406 . In some examples, the computing device  400  may determine an input for the instructions  406  based on sensor data  408  from the position sensor  220 , the strain gauge  222 , the pressure transducer  224 , data input into the computing device  400  by an operator, or other input means. For example, the position sensor  220  or the strain gauge  222  may measure a parameter (e.g., the position of the crankshaft  208 , strain in the chamber  206 ) associated with the pump  100  and transmit associated signals to the computing device  400 . The computing device  400  may receive the signals, extract data from the signals, and store the sensor data  408  in memory  404 . 
     In additional aspects, the computing device  400  may determine an input for the instructions  406  based on pump data  410  stored in the memory  404 . In some aspects, the pump data  410  may be stored in the memory  404  in response to previous determinations by the computing device  400 . For example, the processor  402  may execute instructions  406  to cause the processor  402  to perform pump-monitoring tasks related to the pump rate of the pump  100 , or the flow rate of fluid through the pump  100 . The processor  402  may store flow-rate information that is received during monitoring of the pump  100  as pump data  410  in the memory  404  for further use (e.g., calibrating the pressure pump). In additional aspects, the pump data  410  may include other known information, including, but not limited to, the position of the position sensor  220  or the strain gauge  222  in or on the pump  100 . For example, the computing device  400  may use the position of the position sensor  220  on the power end  202  of the pump  100  to interpret the position signals received from the position sensor  220  (e.g., as a bolt pattern signal). 
     In some aspects, the computing device  400  may generate graphical interfaces associated with the sensor data  408  or pump data  410 , and information generated by the processor  402  therefrom, to be displayed via a display unit  412 . The display unit  412  may be coupled to the processor  402  and may include any CRT, LCD, OLED, or other device for displaying interfaces generated by the processor  402 . In some aspects, the computing device  400  may also generate an alert or other communication of the performance of the pump  100  based on determinations by the computing device  400  in addition to, or instead of, the graphical interfaces. For example, the display unit  412  may include audio components to emit an audible signal when certain conditions are present in the pump  100  (e.g., when the efficiency of one of the pumps  100 ,  102 ,  104  of  FIG. 1  is compromised). 
     The computing device  400  for each of the subsystems  114 ,  116 ,  118  is communicatively coupled to the controller  120 . The controller  120 , similar to the computing device includes a processor  414 , a memory  416 , and a display  422 . The processor  414  and the memory  416  may be similar in type and operation to the processor  402  and the memory  404  of the computing device  400 . The processor  414  may execute instructions  418  stored in the memory  416  for receiving and processing information received from the subsystems  114 ,  116 ,  118 . In some examples, at least some of the memory  416  may include a medium from which the processor  414  can read the instructions  418 . In additional aspects, the processor  414  may determine an input for the instructions  418  based on data  420  stored in the memory  416 . In some aspects, the data  420  may be stored in the memory  416  in response to previous determinations by the controller  120 . For example, the processor  414  may execute instruction  418  to cause the processor  414  to determine whether a pump is operating beyond a cavitation threshold. In another example, the processor  414  may execute instructions  418  to cause the processor  414  to analyze and determine pump rates for the pumps  100 ,  102 ,  104 . The processor  414  may also transmit control signals to the subsystems  116 ,  118 ,  118  to adjust the operations of the pumps  100 ,  102 ,  104 . 
       FIG. 5  is a flow chart of an example of a process for determining a cavitation threshold for each of the pressure pumps  100 ,  102 ,  104  according to one aspect of the present disclosure. The process is described with respect to  FIGS. 1-4 , though other implementations are possible without departing from the scope of the present disclosure. 
     In block  500 , delays in the actuation (e.g., the opening and the closing) of the valves  216 ,  218  are determined. In some aspects, the delays may correspond to the difference in time between the actual opening or closing of the valves  216 ,  218  and the expected opening and closing of the valves  216 ,  218  in light of the position of the plunger  214  in the chamber  206 . 
     In block  502 , a minimum boost pressure is determined in each pump. In some aspects, boost pressure may correspond to the pressure at the inlet of the chamber  206  (e.g., proximate to the suction valve  216 ). The boost pressure may represent the pressure in the chamber  206  during the compression of the pump  100  (e.g., during the time interval between actuation points  902 ,  904  when the suction valve  216  is in an open position). A boost pressure measurement during operation of the pump  100  may be dynamic since the mechanical components of the pressure pump near the inlet to the chamber  206  are constantly in motion. 
     In block  504 , a cavitation threshold is determined for each pump  100 ,  102 ,  104  using the actuation delays corresponding to the valves  216 ,  218  and a minimum boost pressure of each pump  100 ,  102 ,  104 . In some aspects, the cavitation threshold may correspond to a threshold of a boost pressure measurement in each pump that may indicate cavitation conditions. In some aspects, the cavitation conditions may include actual cavitation in the pump. In other aspects, the cavitation conditions may include conditions close to cavitation in the pump. For example, a point of actual cavitation may be determined and a cavitation threshold may include conditions within a predetermined range of the point of actual cavitation. 
       FIG. 6  is a flow chart of an example of a process for determining delays in the actuation of the valves  216 ,  218  in the pressure pumps  100 ,  102 ,  104  as described in block  500  of  FIG. 5 . The process is described with respect to pump  100 , but may be similarly performed for each of the pumps  100 ,  102 ,  104 . 
     In block  600 , a position signal representing a position of the crankshaft  208  of the pump  100  is received. In some aspects, the position signal may be received by the computing device  400  of the subsystem  114  connected to the pump  100 . The position signal may be generated by the position sensor  220  and correspond to the position of a rotating component of a rotating assembly that is mechanically coupled to the plunger  214 . For example, the position sensor  220  may be positioned on a crankcase of the crankshaft  208  to generate signals corresponding to the position, or rotation, of the crankshaft  208 . 
     In block  602 , a strain signal representing strain in the chamber  206  of the pump  100  is received. In some aspects, the strain signal may be generated by the strain gauge  222  and received by the computing device  400 . 
     In block  604 , a position of the plunger  214  is determined using the position signal received in block  600 .  FIGS. 7 and 8  show examples of position signals  700 ,  800  that may be generated by the position sensor  220  during operation of the pump  100  according to some aspects of the present disclosure. In some aspects, the position signals  700 ,  800  may represent the position of the crankshaft  208 , which is mechanically coupled to the plunger  214 .  FIG. 8  shows a position signal  700  displayed in volts over time (in seconds). The position signal  700  may be generated by the position sensor  220  coupled to the power end  202  of the pump  100  and positioned in a path of the crosshead  212 . The position signal  700  may represent the position of the crankshaft  208  over the indicated time as the crankshaft  208  operates to cause the plunger  214  to move within the chamber  206 . The mechanical coupling of the plunger  214  to the crankshaft  208  may allow the computing device to determine a plunger position relative to the position of the crankshaft based on the position signal  700 . 
     In some aspects, the computing device  400  may determine plunger-position reference points  702 ,  704  based on the position signal  700 . For example, the processor  402  may determine dead center positions of the plunger  214  based on the position signal  700 . The dead center positions may include the position of the plunger  214  in which it is farthest from the crankshaft  208 , known as the top dead center. The dead center positions may also include the position of the plunger  214  in which it is nearest to the crankshaft  208 , known as the bottom dead center. The distance between the top dead center and the bottom dead center may represent the length of a full pump stroke of the plunger  214  operating in the chamber  206 . The position signal between the top dead center and the bottom dead center may represent the movement of the crankshaft  208  during a full stroke of the plunger  214  in the chamber  206 . In  FIG. 7 , the top dead center is represented by reference point  702  and the bottom dead center is represented by reference point  704 . In some aspects, the processor  402  may determine the reference points  702 ,  704  by correlating the position signal  700  with a known ratio or other expression or relationship value representing the relationship between the movement of the crankshaft  208  and the movement of the plunger  214 . For example, the mechanical correlations of the crankshaft  208  to the plunger  214  based on the mechanical coupling of the crankshaft  208  to the plunger  214  in the pump  100 ). The computing device  400  may determine the top dead center and bottom dead center based on the position signal  700  or may determine other plunger-position reference points to determine the position of the plunger over a full stroke of the plunger  214 , or a pump cycle of the pump  100 , relative to the position of the crankshaft  208 . 
       FIG. 8  shows a position signal  800  displayed in degrees over time (in seconds) according to some aspects of the present disclosure. The degree value may represent the rotational angle of the crankshaft  208  during operation of the crankshaft  208  or pump  100 . In some aspects, the position signal  800  may be generated by the position sensor  220  located directly on the power end  202  (e.g., positioned directly on the crankshaft  208  or a crankcase of the crankshaft  208 ). The position sensor  220  may generate the position signal  800  based on the bolt pattern of the crankshaft  208  or other suitable target as the position sensor  220  rotates in response to the rotation of the crankshaft  208  during operation. Similar to the position signal  700  shown in  FIG. 7 , the computing device  400  may determine plunger-position reference points  802 ,  804  based on the position signal  800 . The reference points  802 ,  804  represent the top dead center and bottom dead center of the plunger  214  for the chamber  206  during operation of the pump  100 . 
     Returning to  FIG. 6 , in block  606 , actuation points of the suction valve  216  and the discharge valve  218  are determined using the strain signal. The actuation points may represent the point in time where the suction valve  216  and the discharge valve  218  open and close.  FIG. 9  shows an example of a strain signal  900  that may be generated by the strain gauge  222  according to some aspects of the present disclosure. In some aspects, the computing device  400  may determine actuation points  902 ,  904 ,  906 ,  908  of the suction valve  216  and the discharge valve  218  for the chamber  206  based on the strain signal  900 . For example, the computing device  400  may execute instructions  406  including signal-processing processes for determining the actuation points  902 ,  904 ,  906 ,  908 . The computing device  400  may execute instruction  406  to determine the actuation points  902 ,  904 ,  906 ,  908  by determining discontinuities in the strain signal  900 . In some aspects, the stress in the chamber  206  may change during the operation of the suction valve  216  and the discharge valve  218  to cause the discontinuities in the strain signal  900  during actuation of the valves  216 ,  218 . The computing device  400  may identify these discontinuities as the opening and closing of the valves  216 ,  218 . 
     In one example, the strain in the chamber  206  may be isolated to the fluid in the chamber  206  when the suction valve  216  is closed. The isolation of the strain may cause the strain in the chamber  206  to load up until the discharge valve  218  is opened. When the discharge valve  218  is opened, the strain may level until the discharge valve  218  is closed, at which point the strain may unload until the suction valve  216  is reopened. The discontinuities may be present when the strain signal  900  shows a sudden increase or decrease in value corresponding to the actuation of the valves  216 ,  218 . Actuation point  902  represents the suction valve  216  closing, actuation point  904  represents the discharge valve  218  opening, actuation point  906  represents the discharge valve  218  closing, and actuation point  908  represents the suction valve  216  opening to resume the cycle of fluid into and out of the chamber  206 . The exact magnitudes of strain or pressure in the chamber  206  determined by the strain gauge  222  may not be required for determining the actuation points  902 ,  904 ,  906 ,  908 . The computing device  400  may determine the actuation points  902 ,  904 ,  906 ,  908  based on the strain signal  900  providing a characterization of the loading and unloading of the strain in the chamber  206 . Although the actuation points  902 ,  904 ,  906 ,  908  are identified using a strain signal, the valve actuation may be determined using other measurements, including but not limited to, pressure measurements as known in art. 
     Returning to  FIG. 6 , in block  608 , actuation delays for the valves  216 ,  218  may be determined using the actuation points  902 ,  904 ,  906 ,  908  and the plunger position.  FIG. 10  shows the actuation delays for the valves  216 ,  218  according to one aspect of the present disclosure. In  FIG. 10 , the strain signal  900  of  FIG. 10  with the actuation points  902 ,  904 ,  906 ,  908  of the valves  216 ,  218  shown relative to the position of the plunger  214 . The actuation points  902 ,  904  are shown relative to the plunger  214  positioned at the bottom dead center (represented by reference points  704 ,  804 ) for closure of the suction valve  216  and opening of the discharge valve  218 . The actuation points  906 ,  908  are shown relative to the plunger  214  positioned at top dead center (represented by reference points  702 ,  802 ) for opening of the suction valve  216  and closing of the discharge valve  218 . The time distance between the actuation points  902 ,  904 ,  906 ,  908  of the valves  216 ,  218  and the plunger-position reference points  702 ,  704   802 ,  804  may represent the actuation delays of the valves  216 ,  218 . For example, the time between the closing of the suction valve  216  (represented by actuation point  902 ) or the opening of the discharge valve  218  (represented by the actuation point  904 ) and the bottom dead center of the plunger  214  (represented by reference points  704 ,  804 ) may represent compression delays in the actuation of the valves  216 ,  218 . The time between the closing of the discharge valve  218  (represented by actuation point  906 ) or the opening of the suction valve  216  (represented by actuation point  908 ) and the top dead center of the plunger  214  (represented by reference points  702 ,  804 ) may represent decompression delays in the actuation of the valves  216 ,  218 . In some aspects, the delays in the actuation of the valves  216 ,  218  may correspond to the volume of fluid entering or exiting the chamber  206  as the plunger enters and regresses from the chamber  206 . For example, in normal conditions, during compression of the pressure pump  100 , as the plunger  214  regresses from the chamber  206 , fluid will enter the chamber  206  to replace the position of the plunger  214 . The fluid may continue to enter until the suction valve  216  closes at actuation point  902  and the discharge valve  218  opens at actuation point  904  to allow fluid to be discharged from the chamber  206 . The actuation delays may correspond to the volume of fluid entering and exiting the chamber  206  through the valves  216 ,  218 , resulting in incomplete fills of the chamber  206  during each stroke of the plunger  214 . In some aspects, the actuation delays may correspond to cavitation in the chamber  206  where at least a portion of the position of the plunger  214  is displaced with air instead of fluid. 
       FIG. 11  shows an example of a pressure signal  1100  representing boost pressure at the inlet of the chamber  206  as described in block  502  of  FIG. 5 . In some aspects, the pressure signal  1100  may be generated by the pressure transducer  224  positioned at proximate to the inlet of the chamber  206 . As shown, by the pressure signal  1100  the boost pressure may be erratic, causing the pressure signal  1100  to be intervaled peaks. The pressure transducer  224  may include an enveloping filter that may determine a minimum boost pressure  1102  by ramping down the pressure signal  1100  and slowly increasing to trace the lower peaks of the pressure signal  1100 . In some aspects, the enveloping filter may be included in or accessible to the processor  402  of the computing device  400  instead of included in the pressure transducer  224 . The envelope filter may be a digital or analog filter. 
       FIG. 12  is a flow chart of a process for using the actuation delays and the minimum boost pressure  1102  to determine the cavitation threshold. 
     In block  1200 , the actuation delays for each pump  100 ,  102 ,  104  are compared. In some aspects, a comparison of the actuation delays of each pump  100 ,  102 ,  104  may indicate whether cavitation is present in one of the pumps. For example, in some aspects, the actuation delays corresponding to the compression side of the pump  100  (e.g., the delays in the actuation points  900 ,  902  representing the suction valve  216  closing and the discharge valve  218  opening) may be compared to determine cavitation in the chamber  206 . In some aspects, deviations in the timing between the actuation of the same types of valves in each pump  100 ,  102 ,  104  on the compression side of the pumps  100 ,  102 ,  104  may indicate cavitation in the chamber. On the compression side, the deviations may indicate that the suction valves  216  are closing at different times in each of the chambers  206  of the pressure pump represented by the compression actuation delays. The deviations may similarly indicate that the discharge valves  218  are opening at different times in each of the chambers  206 . In some aspects, cavitation may be confirmed by comparing the actuation delays corresponding to the decompression side of the pumps  100 ,  102 ,  104 . For example, where deviations occur on the compression side, but do not occur on the decompression side corresponding to the opening of the suction valves  216  or the closing of the discharge valves  218 , cavitation likely exists. 
       FIG. 13  shows a plot graph  1300  including plot points representing the actuation delays for the suction valve  216  of a set of pressure pump sections having five chambers  206 , collectively. The actuation delays are represented in terms to a fill-percentage of each chamber  206  over time. The plot points indicate that the pressure pumps normally operate at a 98% fill of the respective chambers  206 . 
     Returning to  FIG. 12 , in block  1202 , a point of cavitation in a pump is determined. In some aspects, the point of cavitation may correspond to the time at which cavitation is identified in the chamber  206  of a pressure pump  100 ,  102 ,  104 . Returning to the plot graph  1300  in  FIG. 13 , at approximately 50 seconds, an incomplete fill of the chambers  206  is shown. Based on the trend of the plot points of the plot graph  1300 , the point of cavitation may be determined at 50 seconds. The degree of fill may vary after 50 seconds for each chamber  206  due to variances in the flow paths to each pressure pump section corresponding to the chambers  206 , though the presence of cavitation and the relative severity of the cavitation may be indicated by the relative deviations of fill percentages over time. For example, the plot points representing the actuation delays for chambers 1-4 appear to remain a consistent distance from each other on the y-axis of the plot graph  1300 . But, the plot points representing the actuation delays for chamber 5 deviate from the trend of the plot points for the other chambers. This deviation may indicate cavitation in chamber 5 starting at approximately 50 seconds. 
     Returning to  FIG. 12 , in block  1204 , a minimum boost pressure of the pump at the point of cavitation is determined. In some aspects, the pressure signal  1100  of  FIG. 11  and the plot graph  1300  of  FIG. 13  may be correlated to determine the minimum boost pressure at the point of cavitation. For example, correlating the pressure signal  1100  and the plot graph  1300  may include comparing the two over the same interval of time to determine the boost pressure over the time the plot graph  1300  indicates cavitation in the chamber  206 . For example, based on the minimum boost pressure  1102  for the pressure signal  1100 , the minimum boost point at 50 seconds (the point of cavitation determined in block  1200 ) is approximately −10 pounds per square inch (psi). In some aspects, the point of cavitation may be designated as the cavitation threshold for the corresponding pressure pump  100 ,  102 ,  104 . In other examples, the cavitation threshold may be determined based on a predetermined range from the point of cavitation (e.g., within 5 psi of the point of cavitation). In some aspects, the point of cavitation or the cavitation threshold may be stored as pump data  410  by the computing device  400  of each pump, or as data  420  by the controller  120 . 
       FIG. 14  is a flow chart of an example of a process for avoiding cavitation in a pressure pump according to one aspect of the present disclosure. The process may be described with respect to each of the proceeding figures, though other implementations are possible without departing from the scope of the present disclosure. 
     In block  1400 , a cavitation threshold is determined for each of multiple pumps  100 ,  102 ,  104 . The threshold for each pump may be determined as described in  FIG. 5 . 
     In block  1402 , a pump is identified as having a boost pressure beyond the cavitation threshold. For example, during operation of the pumps  100 ,  102 ,  104 , the controller  120  or the computing device  400  may monitor the boost pressure of each pump  100 ,  102 ,  104 . The controller  120  or the computing device  400  may determine that a pump  100  is approaching the point of cavitation, or is with a predetermined range of the point of the cavitation designated as the cavitation threshold. In some aspects, the controller  120  may retrieve the cavitation threshold from the data  420  of the memory  416 . In other aspects, the controller  120  may receive the cavitation threshold for the computing device  400  corresponding to the pump  100 ,  102 ,  104 . In further aspects, the computing device  400  may retrieve the cavitation threshold for the pump from the pump data  410 . 
     In block  1404 , the pump rate of the pump  100 ,  102 ,  104  identified as operating beyond the cavitation threshold is adjusted. In some aspects, the pump rate may be adjusted by the computing device  400 . In additional aspects, the pump rate may be adjusted in response to a control signal received from the controller  120 . The pump rate may correspond to rate necessary to change the rate of fluid flowing through the pump. For example, in  FIG. 3 , the flow rate through the pump  100  is F AB , the flow rate through the pump  102  is F BC , and the flow rate through the pump  104  is F EF . Adjusting the pump rate for the pumps  100 ,  102 ,  104  may adjust the corresponding flow rate in the same direction. In some aspects, the pump rate of the pump  100 ,  102 ,  104  operating beyond the cavitation threshold may be increased. In other aspects, the pump rate may be decreased. 
     Returning to block  1406 , the pump rate of one or more other pumps  100 ,  102 ,  104  is adjusted in an opposite direction. For example, if the pump  100  is identified as operating beyond the cavitation threshold, the pump rate for the pump  100  may be increased to increase the flow rate, F AB , through the pump  100  in an effort to decrease or stop the cavitation in the chamber  206  of the pump  100 . The pump rates of one or both of the pumps  102 ,  104  may be decreased to maintain the flow rate F 1  into and out of the manifold trailer of  FIG. 3 . In some aspects, the pump  100 ,  102 ,  104  adjusted in the opposite direction of the adjustment to the cavitating chamber may be identified using the minimum boost pressure  1102  corresponding to the chamber of the adjusted pump  100 ,  102 ,  104 . Returning to the example where pump  100  is identified as operating beyond the cavitation threshold (e.g., the chamber corresponding to the pump  100  is cavitating as indicated by the fill percentage shown in  FIG. 13 ), a determination may be made as to which of pumps  102 ,  104  to adjust based on the minimum boost pressure  1102 . The minimum boost pressure  1102  indicates how far the pump (or respective chamber of the pump) is from the cavitation threshold. As such, the chamber operating farthest from the cavitation threshold may have more capacity for a rate adjustment than a chamber operating closer to the cavitation threshold. The minimum boost pressure  1102  indicating that the chamber  106  of pump  102  is farther from the cavitation threshold than that of pump  104  may cause pump  102  to be adjusted to compensate for the cavitation in the chamber  106  of pump  100 . 
     In  1408 , the controller  130  or the computing device  400  may monitor the pump identified in block  1402  to determine if conditions in the pump have improved in response to adjusting the pump rates. In block  1410 , in response to determining that the conditions are improving to reduce or stop cavitation, or move below the threshold, the pumps may be continued to be adjusted in the same directions, and monitored, until the identified pump is no longer beyond the cavitation threshold. For example, the pump rate of pump  100  may be increased and the pump rate of pump  104  may be decreased to compensate for the increase in the pump rate of the pump  100 . Upon determining improvement, the controller  120  may continue to decrease the pump rate of pump  100  and increase the pump rate of pump  104  until cavitation is no longer present. 
     In block  1412 , in response to determining that conditions in the pump have not improved in response to adjusting the pump, the controller  120  or the computing device  400  may adjust the identified pump in the opposite direction. For instance, a pump  100  positioned closest to the inlet of the manifold may a chamber  206  with cavitation due to a high velocity stream of fluid passing by the joint A to supply fluid to the other pumps  102 ,  104  positioned downstream. The high velocity passing by joint A may create a vacuum or reduced pressure, which requires a decrease in the flow rate F AB  through the pump  100 . Returning to the example of block  1410 , subsequent to increasing the pump rate of the pump  100  and decreasing the pump rate of the pump  104 , the controller  120  or the computing device  400  may decrease the pump rate of the pump  100  and increase the pump rate of the pump  104 . 
     In some aspects, monitoring systems and methods may be used according to one or more of the following examples: 
     Example 1 
     A monitoring system may include a plurality of strain gauges positionable on a plurality of pressure pumps to generate strain measurements for the plurality of pressure pumps. The monitoring system may also include a plurality of position sensors positionable on the plurality of pressure pumps to generate position measurements for rotating members of the plurality of pressure pumps. The monitoring system may also include a plurality of pressure transducers positionable on the plurality of pressure pumps to generate boost pressure measurements in a fluid ends of the plurality of pressure pumps, the boost measurements being usable with the strain measurement and the position measurement to determine a cavitation threshold of each pump of the plurality of pressure pumps. 
     Example 2 
     The monitoring system of example 1 may also include a computing device communicatively couplable to the plurality of strain gauges, the plurality of position sensors, and the plurality of pressure transducers to transmit a control signal to a pump of the plurality of pressure pumps operating beyond the cavitation threshold, the control signal corresponding to a first instruction to adjust a first pump rate of the pump in a first direction. 
     Example 3 
     The monitoring system of examples 1-2 may feature the computing device including a processing device for which instructions are executable by the processor to cause the processing device to maintain a total flow rate of fluid through the plurality of pressure pumps by determining a corresponding adjustment to one or more pumps rates of one or more additional pumps of the plurality of pressure pumps in an opposing direction that is opposite to the first direction. 
     Example 4 
     Example 3: The monitoring system of examples 1-3 may feature a processing device for which instructions are executable by the processor to cause the processing device to identify a second pump of the one or more additional pumps based on the boost measurement of the second pump and adjust a corresponding pump rate of the second pump in the opposing direction to maintain the total flow rate through the plurality of pressure pumps, wherein the boost measurement of the second pump indicates that the second pump is farthest below the cavitation threshold. 
     Example 5 
     Example 3: The monitoring system of examples 1-4 may feature the computing device including a processing device for which instructions are executable by the processor to cause the processing device to, subsequent to transmitting the control signal and determining an undesirable change in response to adjusting the first pump rate in the first direction to an adjusted pump rate, transmit a second control signal to a corresponding processing device of the pump, the second control signal corresponding to a second instruction to adjust the adjusted pump rate of the pump in an opposing direction that is opposite to the first direction. 
     Example 6 
     Example 3: The monitoring system of examples 1-5 may also include one or more computing devices communicatively coupled to a pump of the plurality of pressure pumps. The one or more computing devices may include at least one processing device for which instructions are executable by the processor to cause the at least one processing device to determine the cavitation threshold for the pump by (1) determining actuation points for a valve of a chamber of the pump using the strain measurement for a chamber of the pump, (2) determining a position of a displacement member mechanically coupled to the rotating member of the pump using the position measurement for the rotating member of the pump, (3) determining actuation delays corresponding to the valve by correlating the actuation points of the valve and the position of the displacement member, (4) determining a minimum boost pressure of the pump at an inlet to the chamber of the pump based on the boost measurement of the fluid end of the pump, and (5) determining a cavitation boost pressure corresponding to the minimum boost pressure when cavitation is present in the pump using the actuation delays. 
     Example 7 
     The monitoring system of examples 1-6 may feature the at least one processing device including instructions executable by the processing device for causing the processing device to determine when the cavitation boost pressure by (1) comparing the actuation delays to additional actuation delays corresponding to additional pumps of the plurality of pressure pumps, (2) determining a point of cavitation in the pump by identifying deviations in the actuation delays for the pump from a trend of the additional actuation delays of the additional pumps, and (3) comparing the point of cavitation to the minimum boost pressure to determine the minimum boost pressure of the pump at the point of cavitation. 
     Example 8 
     The monitoring system of examples 1-7 may feature a pressure transducer of the plurality of pressure transducers including an enveloping filter to determine the minimum boost pressure of the pump by tracing lower peaks of a pressure signal corresponding to the boost pressure measurement for the pump. 
     Example 9 
     The monitoring system of examples 1-8 may feature the plurality of pumps positioned in parallel between an intake manifold and an outlet manifold that is fluidly couplable to a wellbore to inject fluid from the plurality of pressure pumps into the wellbore to fracture a subterranean formation positioned adjacent to the wellbore. 
     Example 10 
     A method may include determining, by one or more processors, actuation delays for one or more valves in each pump of a plurality of pressure pumps using strain measurements of strain in the plurality of pressure pumps and position measurements for rotating members of the plurality of pressure pumps. The method may also include determining, by the one or more processors, minimum boost pressures for the plurality of pressure pumps. The method may also include determining, by one or more processors, a cavitation threshold for each pump of the plurality of pressure pumps using the actuation delays and the minimum boost pressures. 
     Example 11 
     The method of example 10 may feature determining the actuation delays for the one or more valves of the plurality of pressure pumps to include, for at least one pump of the plurality of pressure pumps (1) receiving, from a position sensor, a position signal representing the position measurement for the at least one pump, (2) receiving, from a strain gauge, a strain signal representing the strain measurement for a chamber of the at least one pump, (3) determining a position of a displacement member mechanically coupled to the rotating member using the position signal, (4) determining actuation points of a valve of the chamber, and (5) correlating the position of the displacement member and the actuation points of the valve to determine the actuation delays for the at least one pump. 
     Example 12 
     The method of examples 10-11 may feature determining a minimum boost pressure for a pump of the plurality of pumps to include tracing low peaks of a pressure signal generated by a pressure transducer coupled to an inlet of a chamber of the pump. 
     Example 13 
     The method of examples 10-12 may feature determining the cavitation threshold for each pump to include, for at least one pump of the plurality of pressure pumps (1) comparing the actuation delays of the at least one pump with additional actuation delays for additional pumps of the plurality of pumps, (2) determining a point of cavitation in the at least one pump based on the actuation delays, and (3) determining the minimum boost pressure for the at least one pump at the point of cavitation. 
     Example 14 
     The method of examples 10-13 may also include identifying, by the one or more processors, a pump of the plurality of pumps having a boost pressure beyond the cavitation threshold determined for the pump. The method may also include adjusting, by the one or more processors, a pump rate of the pump in a first direction. The method may also include maintaining, by the one or more processors, a total pump rate of the plurality of pressure pumps. The method may also include determining a change in the boost pressure for the pump in response to adjusting the pump rate to an adjusted pump rate. 
     Example 15 
     The method of examples 10-14 may feature maintaining the total pump rate of the plurality of pressure pumps to include adjusting a second pump rate of a second pump of the plurality of pump in a second direction opposite the first direction. 
     Example 16 
     The method of examples 10-15 may feature adjusting the second pump rate of the second pump in a second direction to include identifying the second using a second boost pressure corresponding to the second pump. 
     Example 17 
     The method of examples 10-16 may also include, in response to determining an undesirable change in the boost pressure for the pump at the adjusted pump rate, adjusting, by the one or more processors, the adjusted pump rate in a second direction opposite the first direction. 
     Example 18 
     A system may include a plurality of pressure pumps positioned between an intake manifold and an output manifold, each pump of the plurality of pumps including a fluid chamber positionable in a fluid end of each pump and including a valve to control a flow of fluid through each pump, each pump having a strain in the fluid chamber being measurable by a strain gauge and a boost pressure proximate to the valve being measurable by a pressure transducer. Each pump may also include a rotating member positionable in a power end of each pump to control movement of a displacement member in the fluid chamber, a position of the rotating member being measurable by a position sensor. The system may also include one or more computing devices communicatively coupled to plurality of pressure pumps to identify a cavitation threshold representing a boost pressure measurement indicative of potential cavitation for each pump of the plurality of pumps using a position measurement generated by the position sensor, a strain measurement generated by the strain gauge, and a pressure measurement generated by the pressure transducer. 
     Example 19 
     The system of example 18 may feature the one or more computing devices includes at least one processing device for which instructions are executable by the at least one processing device to cause the at least one processing device to (1) determine, for each pump of the plurality of pumps, actuation delays for the valve using a strain measurement generated by the strain gauge and a position measurement generated by the position sensor, (2) determine, for each pump, a minimum boost pressure proximate to the valve, and (3) determine, for each pump, the cavitation threshold by using the actuation delays and the minimum boost pressure to identify the minimum boost pressure at a point of cavitation for each pump. 
     Example 20 
     The system of examples 18-19 may feature the one or more computing devices including at least one processing device for which instructions are executable by the at least one processing device to cause the at least one processing device to (1) identify a pump of the plurality of pressure pumps having a boost pressure beyond the cavitation threshold, (2) adjust a first pump rate of the pump in a first direction, and (3) adjust a second pump rate of another pump of the plurality of pressure pumps in a second direction that is opposite the first direction to maintain a constant total pump rate for the plurality of pressure pumps into the intake manifold and out of the output manifold. 
     The foregoing description of the examples, including illustrated examples, has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the subject matter to the precise forms disclosed. Numerous modifications, combinations, adaptations, uses, and installations thereof can be apparent to those skilled in the art without departing from the scope of this disclosure. The illustrative examples described above are given to introduce the reader to the general subject matter discussed here and are not intended to limit the scope of the disclosed concepts.