Patent Publication Number: US-2021172435-A1

Title: Flow regulating pump, system, and method

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a divisional of U.S. application Ser. No. 15/727,188 filed Oct. 6, 2017 for “FLOW REGULATING PUMP, SYSTEM, AND METHOD” by T. A. Anderson, V. K. Nguyen and P. F. Boschert, which in turn claims the benefit of U.S. Provisional Application No. 62/414,168 filed Oct. 28, 2016, and entitled “LOW FLOW PLURAL COMPONENT MATERIAL PROPORTIONING,” the disclosures of which are hereby incorporated in their entirety. 
    
    
     BACKGROUND 
     This disclose relates to generally to flow control. More particularly, this disclosure relates to a system and method for isolating a downstream flow from an upstream flow. 
     Materials, such as paint, water, oil, stains, finishes, epoxies, aggregate, coatings, adhesives, sealants, and solvents, among other options, can require low pressures and flow rates for application. Fluid regulating devices, such as control valves and pressure regulators, can be used to alter the upstream fluid pressure to a downstream material flow rate and/or pressure. The downstream pressure and/or flow rate provided by the flow regulating devices are dependent on the upstream pressure. Where the material is a plural component material, the material supply can have a minimum flow rate and pressure much higher than the desired downstream flow rate and pressure. The differential between the desired downstream flow rate and the minimum flow rate from the material supply can affect the accuracy of the mix ratio. 
     SUMMARY 
     According to one aspect of the disclosure, a flow regulating system includes a first regulator pump, a material supply disposed upstream of the first regulator pump, and an applicator disposed downstream of the first regulator pump. The regulator pump includes a first fluid chamber, a first inlet valve configured to control a fluid flow into the first fluid chamber, a first outlet valve configured to control the fluid flow out of the first fluid chamber, a first fluid displacement member at least partially bounding the first fluid chamber, the first fluid displacement member configured to drive a material downstream through the first outlet valve at a first pressure, and a first status sensor connected to the first regulator pump, the first status sensor configured to generate a first fill signal based on the volume of material within the fluid chamber being at a refill volume and to generate a first pump full signal based on the volume of material within the fluid chamber being at a full volume. The material supply is fluidly connected to the first inlet valve and configured to provide the material to the first inlet valve at a second pressure. The applicator is fluidly connected to the first outlet valve. The first regulator pump is configured to fluidly isolate the material supply from the applicator such that the first pressure is independent of and unaffected by the second pressure. 
     According to another aspect of the disclosure, a regulator pump includes a fluid chamber, an inlet valve disposed configured to control a fluid flow into the fluid chamber, an outlet valve configured to control the fluid flow out of the fluid chamber, a fluid displacement member at least partially bounding the fluid chamber, the fluid displacement member configured to drive a material downstream through the outlet valve at a downstream pressure, and a status sensor connected to the regulator pump. The status sensor can be configured to generate a fill signal based on the volume of material within the fluid chamber being at a refill volume and to generate a pump full signal based on the volume of material within the fluid chamber being at a full volume. The outlet valve is configured to be in an open position only when the inlet valve is in a closed position such that the downstream pressure is isolated from and independent of an upstream pressure. 
     According to yet another aspect of the disclosure, a method of flow control includes generating a first fill signal based on an actual material volume in a first fluid chamber of a first regulator pump being at a refill volume; proceeding through a first pump refill cycle based on a first fill command to fill the first regulator pump with material, wherein the first fluid chamber is fluidly isolated from a downstream material flow during the first pump refill cycle and the first fluid chamber is fluidly connected to an upstream material flow during the first pump refill cycle; and proceeding through a first pump dispense cycle based on a first dispense command, wherein the first fluid chamber is fluidly isolated from the upstream material flow during the first pump dispense cycle and the first fluid chamber is fluidly connected to the downstream material flow during the first pump dispense cycle, and wherein the first regulator pump generates a downstream pressure to drive the material downstream out of the first fluid chamber during the first pump dispense cycle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic block diagram of a flow regulating system. 
         FIG. 2  is a schematic block diagram of a flow regulating system. 
         FIG. 3  is a schematic block diagram of a flow regulating system having multiple regulator pumps. 
         FIG. 4  is a schematic block diagram of a flow regulating system having multiple regulator pumps. 
         FIG. 5A  is an isometric view of a regulator pump. 
         FIG. 5B  is a cross-sectional view of the regulator pump of  FIG. 5A  taken along line B-B in  FIG. 5A . 
         FIG. 6A  is an isometric view of a regulator pump. 
         FIG. 6B  is a cross-sectional view of the regulator pump of  FIG. 6A  taken along line B-B in  FIG. 6A . 
         FIG. 6C  is a cross-sectional view of the regulator pump of  FIG. 6A  taken along line C-C in  FIG. 6A . 
         FIG. 6D  is a cross-sectional view of the regulator pump of  FIG. 6A  taken along line D-D in  FIG. 6A . 
         FIG. 7A  is a flow diagram of a regulator pump refill cycle. 
         FIG. 7B  is a flow diagram of a regulator pump dispense cycle. 
         FIG. 8  is a flow diagram depicting a method of dispensing material in a multiple regulator pump system. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a schematic block diagram flow regulating system  10 . Flow regulating system  10  includes controller  12 , material supply  14 , regulator pump  16 , applicators  18 , actuator  20 , low pressure hose  22 , high pressure hose  24 , communication links  26   a  and  26   b,  actuator lines  28   a  and  28   b,  and pressure line  30 . Controller  12  includes memory  32 , processor  34 , and user interface  36 . Regulator pump  16  includes inlet valve  38   a,  outlet valve  38   b,  and status sensor  40 . 
     Inlet valve  38   a  is disposed on regulator pump  16  and controls a flow of material into regulator pump  16 . Outlet valve  38   b  is similarly disposed on regulator pump  16  and controls a flow of material out of regulator pump  16 . Material supply  14  is connected to inlet valve  38   a  by high pressure hose  24 . Material supply  14  provides a flow of material to regulator pump  16  at an upstream pressure. Applicators  18  are connected to outlet valve  38   b  by low pressure hose  22 . Regulator pump  16  drives the material received from material supply  14  downstream to applicators  18  at a downstream pressure, isolated from and independent of the upstream pressure. Applicators  18  are configured to apply the material received from regulator pump  16  at a desired location. 
     Actuator  20  is connected to inlet valve  38   a  by actuator line  28   a  and connected to outlet valve  38   b  by actuator line  28   b.  Actuator  20  is configured to control the positions of inlet valve  38   a  and outlet valve  38   b  between an open position and a closed position. For example, actuator  20  can provide a flow of motive fluid, such as air or a hydraulic fluid, to cause the shift between the open and closed positions. In one example, actuator  20  includes a three-way valve, such as a three-way solenoid valve, to control the flow of motive fluid to one of inlet valve  38   a  and outlet valve  38   b,  while venting motive fluid from the other of inlet valve  38   a  and outlet valve  38   b.  Actuator  20  controls the positions of inlet valve  38   a  and outlet valve  38   b  such that outlet valve  38   b  is open only when inlet valve  38   a  is closed, and inlet valve  38   a  is open when outlet valve  38   b  is closed. As such, the downstream pressure remains isolated from and unaffected by the upstream pressure. While actuator  20  is described as shifting inlet valve  38   a  and outlet valve  38   b  with motive fluid, it is understood that actuator can cause inlet valve  38   a  and outlet valve  38   b  to shift in any desired manner. 
     Actuator  20  is connected to regulator pump  16  by pressure line  30 . Actuator  20  is configured to control regulator pump  16  to cause regulator pump  16  to generate and maintain the downstream pressure in low pressure hose  22 . In some examples, actuator  20  can provide a working fluid, such as air or hydraulic fluid, to regulator pump  16  to drive a fluid displacement member of regulator pump  16 , such as a diaphragm or piston, such that the fluid displacement member drives the material downstream through outlet valve  38   b.  It is understood, however, that actuator  20  can be of any desired configuration for controlling inlet valve  38   a  and outlet valve  38   b,  such as pneumatically controlled, motor controlled, electrically controlled, or of any other desired configuration. 
     Controller  12  communicates with actuator  20  via communication link  26   a.  Controller  12  is configured to provide commands to actuator  20  to control the position of inlet valve  38   a  and outlet valve  38   b,  and to control the downstream pressure generated by regulator pump  16 . 
     Controller  12  communicates with status sensor  40  via communication link  26   b.  Status sensor  40  is configured to monitor regulator pump  16 , such as whether regulator pump  16  should enter a refill cycle, has completed a refill cycle, and/or is ready for a dispense cycle, among others. Status sensor  40  can provide the regulator pump status to controller  12  via communication link  26   b.  For example, status sensor  40  can sense that the volume of material remaining in regulator pump  16  has reached a refill level. In response to status sensor  40  sensing the refill level, status sensor  40  can generate a fill signal indicating that regulator pump  16  needs to be refilled and can communicate the fill signal to controller  12  via communication link  26 b. Status sensor  40  can further sense when regulator pump  16  has been filled and has thus completed the refill cycle. When regulator pump  16  has completed the refill cycle, regulator pump  16  is ready to proceed through a dispense cycle and dispense material downstream to applicators  18 . Status sensor  40  can generate a pump full signal in response to sensing that the regulator pump  16  is full of material, and can communicate the pump full signal to controller  12 . 
     While controller  12  is shown as communicating through communication links  26   a  and  26   b,  it is understood that controller  12  can communicate with actuator  20  and regulator pump  16  in any desired manner, such as wireless networks or wired networks or both. In some examples, actuator  20  can be integrated into controller  12 . User interface  36  allows a user to provide inputs to and receive outputs from controller  12 . User interface  36  can be of any suitable configuration for, such as a keyboard, touchscreen, or other suitable interface device. 
     Memory  32  stores software that, when executed by processor  34 , commands inlet valve  38   a  and outlet valve  38   b  between an open position and a closed position. Memory  32  further stores software that, when executed by processor  34 , provides controls regulator pump  16  to provide a desired downstream pressure and/or flow rate of material. 
     Processor  34 , in one example, is configured to implement functionality and/or process instructions. For instance, processor  34  can be capable of processing instructions stored in memory  32 . Examples of processor  34  can include any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other equivalent discrete or integrated logic circuitry. 
     Memory  32 , in some examples, can be configured to store information during operation. Memory  32 , in some examples, is described as computer-readable storage media. In some examples, a computer-readable storage medium can include a non-transitory medium. The term “non-transitory” can indicate that the storage medium is not embodied in a carrier wave or a propagated signal. In certain examples, a non-transitory storage medium can store data that can, over time, change (e.g., in RAM or cache). In some examples, memory  32  is a temporary memory, meaning that a primary purpose of memory  32  is not long-term storage. Memory  32 , in some examples, is described as volatile memory, meaning that memory  32  does not maintain stored contents when power to controller  12  is turned off. Examples of volatile memories can include random access memories (RAM), dynamic random access memories (DRAM), static random access memories (SRAM), and other forms of volatile memories. In some examples, memory  32  is used to store program instructions for execution by processor  34 . Memory  32 , in one example, is used by software or applications running on controller  12  to temporarily store information during program execution. 
     Memory  32 , in some examples, can also include one or more computer-readable storage media. Memory  32  can be configured to store larger amounts of information than volatile memory. Memory  32  can further be configured for long-term storage of information. In some examples, memory  32  includes non-volatile storage elements. Examples of such non-volatile storage elements can include magnetic hard discs, optical discs, floppy discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories. 
     Regulator pump  16  is configured to isolate the downstream flow of material to applicators  18  from the upstream flow of material provided by material supply  14 . As such, the downstream pressure is independent of and unaffected by the upstream pressure. By way of example, a refill cycle and a dispense cycle of regulator pump  16  will be discussed below. 
     During operation, regulator pump  16  drives the material downstream through outlet valve  38   b  and low pressure hose  22  at a desired downstream pressure. As regulator pump  16  drives the material downstream, inlet valve  38   a  remains in the closed position to ensure that the upstream pressure has no effect on the downstream pressure generated by regulator pump  16 . When status sensor  40  senses that the material in regulator pump  16  reaches the refill volume status sensor  40  can generate the fill signal indicating that regulator pump  16  should enter the refill cycle. Status sensor  40  communicates the fill signal to controller  12 . Controller  12  can generate a fill command based on the fill signal. While controller  12  is described as generating the fill command based on the fill signal, it is understood that controller  12  can generate the fill command based on one or more signals. For example, where flow controlling system  10  includes a single regulator pump  16 , controller  12  can generate the fill command based on receiving the fill signal and an end-of-application signal indicating that the current application cycle at applicators  18  is complete. Generating the fill command based at least in part on the end-of-application signal ensures that regulator pump  16  does not begin the refill cycle while applicators  18  are applying the material. 
     Outlet valve  38   b  shifts to the closed position and inlet valve  38   a  shifts to the open position in response to the fill command. Controller  12  can provide the fill command to actuator  20  to cause actuator  20  to shift outlet valve  38   b  and inlet valve  38   a.  For example, actuator  20  can vent the motive fluid from outlet valve  38   b,  causing outlet valve  38   b  to close, and can supply motive fluid to inlet valve  38   a,  causing inlet valve  38   a  to open. With outlet valve  38   b  in the closed positon, any material within regulator pump  16  is isolated from low pressure hose  22  such that a pressure within regulator pump  16  has no effect on the downstream fluid pressure. With inlet valve  38   a  in the open position, material flows into regulator pump  16  from high pressure hose  24  and material supply  14 . Material supply  14  drives the material through high pressure hose  24  at any upstream pressure required to maintain the integrity and desired material properties of the material being supplied. For example, where material supply  14  provides a multiple component material, the pressure required to accurately provide and maintain the desired mix ratio of the multiple component material can be significantly higher than the desired downstream pressure at applicators  18 , particularly at high mix ratios, such as 30:1 or higher. 
     Material supply  14  continues to drive material into regulator pump  16 . Status sensor  40  can sense when regulator pump  16  is refilled and can generate a pump full signal based on regulator pump  16  being refilled. Status sensor  40  can provide the pump full signal to controller  12 , and controller  12  can generate a command based on the pump full signal. The pump full signal indicates that regulator pump  16  has completed the refill cycle and is primed for the dispense cycle. In some examples, controller  12  can generate a valve close command based on the pump full signal. Inlet valve  38   a  can shift to the closed position in response to the valve close command. In other examples, inlet valve  38   a  can remain open such that the material deadheads within regulator pump  16  until regulator pump  16  enters the dispense cycle. 
     During the dispense cycle, inlet valve  38   a  is closed and outlet valve  38   b  is opened. Regulator pump  16  drives the material downstream through outlet valve  38   b  to generate the downstream pressure and flow rate. Controller  12  can generate a dispense command based on the pump full signal. In some examples, inlet valve  38   a  shifts to the closed position and outlet valve  38   b  shifts to the open position in response to the dispense command. For example, controller  12  can communicate the dispense command to actuator  20 , and actuator  20  can vent the motive fluid from inlet valve  38   a,  causing inlet valve  38   a  to close, and can supply motive fluid to outlet valve  38   b,  causing outlet valve  38   b  to open. With inlet valve  38   a  closed, any material downstream of inlet valve  38   a  is isolated from the upstream pressure. With outlet valve  38   b  open, regulator pump  16  is fluidly connected to low pressure hose  22  and can drive material downstream through outlet valve  38   b.    
     Regulator pump  16  is configured to drive the material downstream through low pressure hose  22  and to applicators  18  in response to the dispense command. In some examples, actuator  20  provides working fluid, such as compressed air or hydraulic fluid, to regulator pump  16  through pressure line  30  to generate a driving pressure within regulator pump  16 . Regulator pump  16  can be configured such that the downstream pressure in low pressure hose  22  has any desired pressure ratio with the working fluid. For example, regulator pump  16  can provide a 1:1 pressure ratio between the working fluid pressure and the downstream pressure. As such, controlling the working fluid pressure controls the downstream pressure. While regulator pump  16  is described as generating the downstream pressure based on the working fluid pressure, it is understood that regulator pump  16  can generate the downstream pressure in any suitable manner. For example, the fluid displacement member of regulator pump  16  can be electronically controlled, such as by a solenoid. Outlet valve  38   b  can remain in the open position throughout the dispense cycle to maintain the downstream pressure within low pressure hose  22 . As such, the material within low pressure hose  22  remains pressurized and ready to dispense when applicators  18  are activated. It is further understood that downstream flow and/or pressure regulators can be utilized to further control the downstream pressure at applicators  18 . 
     Actuator  20  can receive feedback to continuously monitor the working fluid pressure to maintain the desired downstream pressure. For example, a pressure sensor or flow rate sensor can be connected to low pressure hose and/or applicators  18  to provide feedback to actuator  20 . Regulator pump  16  can continue to supply the material to applicators  18  throughout the dispense cycle until status sensor  40  generates the fill signal, thereby indicating that regulator pump  16  should again enter the refill cycle. 
     Fluid regulating system  10  provides significant advantages. Regulator pump  16  fully isolates the downstream pressure within low pressure hose  22  from the upstream pressure within high pressure hose  24  such that the downstream pressure is unaffected by the upstream pressure. Isolating the upstream pressure from the downstream pressure allows the material to be applied from regulator pump  16  at low flow rates, such as about 0.03-0.07 fl. oz/min. (1-2 cc/min.), while being supplied to regulator pump  16  at relatively high flow rates, such as about 0.4 fl.oz/min. (12 cc/min.) or higher. Moreover, isolating the upstream pressure from the downstream pressure increases the consistency of the material provided to applicators  18 . Where the material is a multiple component material, the material may require a high mix ratio, the accuracy of which are difficult to maintain at low flow rates. As such, regulator pump  16  allows the material to be mixed at the high mix ratio and at a high flow rate to ensure that regulator pump  16  receives the mixed material at the desired ratio. Regulator pump  16  provides the mixed material, which is already at the desired mix ratio, to applicators  18  at whatever fluid pressure and flow rate is desired. Moreover, where regulator pump  16 , including inlet valve  38   a  and outlet valve  38   b,  are pneumatically controlled, such as by actuator  20 , flow regulating system  10  can be utilized in Class I, Division I, hazardous locations. 
       FIG. 2  is a schematic block diagram of flow regulating system  10 ′. Flow regulating system  10 ′ includes material supply  14 , regulator pump  16 , applicators  18 , and actuator  20 . Regulator pump  16  includes inlet valve  38   a,  outlet valve  38   b,  and status sensor  40 . Inlet valve  38   a  is disposed on regulator pump  16  and controls a flow of material into regulator pump from material supply  14 . Material supply  14  is fluidly connected to regulator pump  16  by high pressure hose  24 . Outlet valve  38   b  is disposed on regulator pump  16  and controls a flow of material downstream out of regulator pump  16 . Low pressure hose  22  extends between and fluidly connects outlet valve  38   b  and applicators  18 . Actuator  20  is connected to inlet valve  38   a  by actuator line  28   a  and to outlet valve  38   b  by actuator line  28   b.  Actuator  20  is connected to regulator pump  16  by pressure line  30 . Actuator  20  can receive signals from status sensor  40  via communication link  26 , which can be any suitable link for providing signals to actuator  20 , such as a wired, wireless, or pneumatic connection, among others. 
     When regulator pump  16  is ready for a refill cycle, status sensor  40  can generate a fill signal. Status sensor  40  can provide the fill signal to actuator  20  via communication link  26 . The fill signal can function as a fill command, thereby causing the actuator  20  to shift outlet valve  38   b  to a closed position and to shift inlet valve  38   a  to an open position. For example, actuator  20  can include a three-way solenoid valve responsive to signals from status sensor  40 . The fill signal can cause the three-way solenoid to shift positions such that motive fluid, such as compressed air or non-compressible hydraulic fluid, is provided to inlet valve  38   a  and vented from outlet valve  38   b.  With outlet valve  38   b  closed, the downstream pressure is isolated from regulator pump  16  such that any pressure within regulator pump  16  has no effect on the downstream pressure. With inlet valve  38   a  open, regulator pump  16  is fluidly connected to material source  14 , and the upstream pressure within high pressure hose  24  drives the material into regulator pump  16 . 
     Status sensor  40  senses when regulator pump  16  has completed the refill cycle and generates a pump full signal in response thereto. Status sensor  40  can provide the pump full signal to actuator  20  via communication link  26 . The pump full signal can function as a dispense command, causing inlet valve  38   a  to shift to the closed position and outlet valve  38   b  to shift to the open position. In some examples, actuator  20  can include a three-way solenoid valve responsive to signals from status sensor  40 . The pump full signal can cause the three-way solenoid to shift positions such that motive fluid, such as compressed air or non-compressible hydraulic fluid, is provided to outlet valve  38   b  and vented from inlet valve  38   a.  With outlet valve  38   b  open, applicators  18  are fluidly connected to regulator pump  16  such that regulator pump  16  can generate the downstream pressure. With inlet valve  38   a  closed, regulator pump  16  is fluidly isolated from material source  14 , such that the upstream pressure within high pressure hose  24  has no effect on the downstream pressure or the pressure within regulator pump  16 . 
     Further in response to the pump full signal, actuator  20  can provide a working fluid, such as compressed air or a non-compressible hydraulic fluid, to regulator pump  16 . The working fluid can create a pressure within regulator pump  16  to drive the material downstream to applicators  18 . While actuator  20  is described as providing the working fluid, it is understood that the source of the working fluid can be separate from the source of the motive fluid. With the downstream pressure fully isolated from the upstream pressure, regulator pump  16  creates and maintains the downstream pressure. As such, the downstream pressure is controllable regardless of and independent from the upstream pressure. 
     Flow controlling system  10 ′ provides significant advantages. Status sensor  40  can provides signals directly to actuator  20  to cause actuator  20  initiate the refill cycle and the dispense cycle. As such, regulator pump  16  can automatically proceed through refill and dispense cycles. Regulator pump  16  fully isolates the downstream pressure within low pressure hose  22  from the upstream pressure within high pressure hose  24  such that the downstream pressure is unaffected by the upstream pressure. Isolating the upstream pressure from the downstream pressure allows the material to be applied from regulator pump  16  at low flow rates, such as about 0.03-0.07 fl. oz/min. (1-2 cc/min.), while being supplied to regulator pump  16  at relatively high flow rates, such as about 0.4 fl.oz/min. (12 cc/min.) or higher. Moreover, where regulator pump  16 , including inlet valve  38   a  and outlet valve  38   b,  are pneumatically controlled, such as by actuator  20 , flow regulating system  10  can be utilized in Class I, Division I, hazardous locations. 
       FIG. 3  is a schematic of flow regulating system  10 ″ having multiple regulator pumps  16   a  and  16   b.  Flow regulating system  10 ″ includes controller  12 , material supply  14 , regulator pump  16   a,  regulator pump  16   b,  applicators  18 , and actuator  20 . Controller  12  includes memory  32 , processor  34 , and user interface  36 . Regulator pump  16   a  includes inlet valve  38   a,  outlet valve  38   b,  and status sensor  40   a.  Regulator pump  16   b  includes inlet valve  38   c,  outlet valve  38   d,  and status sensor  40   b.    
     Inlet valve  38   a  is disposed on regulator pump  16   a  and controls a flow of material into regulator pump  16   a.  Outlet valve  38   b  is disposed on regulator pump  16   a  and controls a flow of material out of regulator pump  16   a.  High pressure hose  24   a  extends between and connects material supply  14  and inlet valve  38   a,  and high pressure hose  24   a  is configured to provide material to regulator pump  16   a  from material supply  14 . Low pressure hose  22   a  extends between and connects outlet valve  38   b  and applicators  18 , and low pressure hose  22   a  is configured to provide material to applicators  18  from regulator pump  16   a.  Status sensor  40   a  is disposed on regulator pump  16   a  and is configured to monitor regulator pump  16   a.  Status sensor  40   a  is configured to communicate with controller  12  via communication link  26   b,  which can be a wired or wireless connection. 
     Inlet valve  38   c  is disposed on regulator pump  16   b  and controls a flow of material into regulator pump  16   b.  Outlet valve  38   d  is disposed on regulator pump  16   b  and controls a flow of material out of regulator pump  16   b.  High pressure hose  24   b  extends between and connects material supply  14  and inlet valve  38   c,  and high pressure hose  24   b  is configured to provide material to regulator pump  16   b  from material supply  14 . Low pressure hose  22   b  extends between and connects outlet valve  38   d  and applicators  18 , and low pressure hose  22   b  is configured to provide material to applicators  18  from regulator pump  16   b.  Status sensor  40   b  is disposed on regulator pump  16   b  and is configured to monitor regulator pump  16   b.  Status sensor  40   b  is configured to communicate with controller  12  via communication link  26   c,  which can be a wired or wireless connection. 
     Material supply  14  drives material through both high pressure hose  24   a  and high pressure hose  24   b.  The material can be a single component material or a plural component material. Material supply  14  is configured to drive the material at any pressure and flow rate required to maintain the integrity and desired material properties of the material. 
     Actuator  20  is connected to inlet valve  38   a  via actuator line  28   a,  to outlet valve  38   b  via actuator line  28   b,  to inlet valve  38   c  via actuator line  28   c,  and to outlet valve  38   d  via actuator line  28   d.  Actuator  20  is configured to provide motive fluid, such as air or non-compressible hydraulic fluid, to inlet valves  38   a  and  38   c  and to outlet valves  38   b  and  38   d  to cause inlet valves  38   a  and  38   c  and outlet valves  38   b  and  38   d  to shift between a closed position and an open position. For example, actuator  20  can provide the motive fluid to inlet valve  38   a  to cause inlet valve  38   a  to shift from the closed position to the open position, and actuator  20  can simultaneously vent motive fluid from outlet valve  38   b  to cause outlet valve  38   b  to shift from the open position to the closed position, such that material cannot flow through outlet valve  38   b  when inlet valve  38   a  is open. In some examples, actuator  20  can include multiple control valves, with individual control valves dedicated to each regulator pump  16 . For example, actuator  20  can include a first three-way solenoid valve connected to inlet valve  38   a  and outlet valve  38   b  to control the supply of motive fluid to inlet valve  38   a  and outlet valve  38   b.  Actuator  20  can further include a second three-way solenoid valve connected to inlet valve  38   c  and outlet valve  38   d  to control the supply of motive fluid to inlet valve  38   c  and outlet valve  38   d.  It is understood, however, that actuator  20  controls the opening and closing sequences such that inlet valves  38   a  and  38   c  remain closed whenever outlet valves  38   b  and  38   d  are open. As such, the downstream fluid pressure in low pressure hoses  22   a  and  22   b  remains isolated from and unaffected by the upstream fluid pressure in high pressure hoses  24   a  and  24   b.    
     Actuator  20  is connected to regulator pump  16   a  via pressure line  30   a  and to regulator pump  16   b  via pressure line  30   b.  Actuator  20  can provide a working fluid, such as compressed air or a non-compressible hydraulic fluid, to regulator pumps  16   a  and  16   b  during a dispense cycle, to cause regulator pumps  16   a  and  16   b  to drive material downstream and to generate the downstream pressure. 
     Controller  12  can control the opening and closing of inlet valves  38   a  and  38   c  and outlet valves  38   b  and  38   d.  Controller  12  can further control regulator pumps  16   a  and  16   b  to control the downstream pressure. Memory  32  stores software that, when executed by processor  34  is configured to control the opening and closing of inlet valves  38   a  and  38   c  and outlet valves  38   b  and  38   d.  The software stored on memory  32  can be further configured to, when executed by processor  34 , control the flow of working fluid to regulator pump  16   a  and regulator pump  16   b  to thereby control the downstream pressure in low pressure hose  22   a  and low pressure hose  22   b,  respectively. Controller  12  communicates with actuator  20  via communication link  26   a,  with status sensor  40   a  via communication link  26   b,  and with status sensor  40   b  via communication link  26   c.    
     During operation, one of regulator pump  16   a  and regulator pump  16   b  is configured to proceed through a fill cycle while the other of regulator pump  16   a  and regulator pump  16   b  proceeds through a dispense cycle. By way of example, a flow control cycle where outlet valve  38   b  of regulator pump  16   a  is initially open, such that regulator pump  16   a  is providing material to applicators  18 , and outlet valve  38   d  of regulator pump  16   b  is initially closed, such that regulator pump  16   b  is disconnected from applicators  18 , is described below. 
     Regulator pump  16   a  drives the material downstream to applicators  18  until status sensor  40   a  senses when the volume of material in regulator pump  16   a  has reached a refill level, such that regulator pump  16   a  and is ready to be refilled. Status sensor  40   a  generates a first fill signal based on the volume of material within regulator pump  16   a  reaching the refill level. Status sensor  40   a  provides the first fill signal to controller  12  via communication link  26   b.  In response to the first fill signal, controller  12  generates a first dispense command, to cause regulator pump  16   b  to enter the dispense cycle, and a first fill command, to cause regulator pump  16   a  to enter the refill cycle. Controller  12  can communicate the first fill command and the first dispense command to actuator  20 . 
     In response to the first dispense command, actuator  20  causes outlet valve  38   d  to shift to the open position and causes inlet valve  38   c  to shift to the open position. In one example, actuator  20  provides motive fluid, such as air or a non-compressible hydraulic fluid, to outlet valve  38   d  via actuator line  28   d  to cause outlet valve  38   d  to shift to the open position. Simultaneously, actuator  20  can vent motive fluid from inlet valve  38   c  via actuator line  28   c  such that inlet valve  38   c  shifts to the closed positon. With inlet valve  38   c  closed, the material within regulator pump  16   b  is isolated from the upstream fluid pressure in high pressure hose  24   b.  With outlet valve  38   d  open, the material within regulator pump  16   b  is connected to applicators  18  via low pressure hose  22   b.    
     Actuator  20  is further configured to provide working fluid to regulator pump  16   b  in response to the first dispense signal. Actuator  20  provides the working fluid at a pressure required to drive the material out of regulator pump  16   b  at the desired downstream pressure and flow rate. The working fluid drives a fluid displacement member within regulator pump  16   b  through a pressure stroke, and the fluid displacement member drives the material out of regulator pump  16   b.  Regulator pump  16   b  continues through the dispense cycle until status sensor  40   b  senses that a volume of material in regulator pump  16   b  reaches a refill level and generates a second fill signal. 
     As regulator pump  16   b  enters the dispense cycle, regulator pump  16   a  simultaneously enters the refill cycle. By causing one of regulator pump  16   a  and  16   b  to enter the dispense cycle when the other of regulator pump  16   a  and  16   b  enters the refill cycle, flow regulating system  10  ensures a continuous supply of material is available to applicators  18 . 
     In response to the first fill command, actuator  20  causes outlet valve  38   b  to close and causes inlet valve  38   a  to open. In one example, actuator  20  vents motive fluid from outlet valve  38   b  via actuator line  28   b  to cause outlet valve  38   b  to shift to the closed position, and actuator  20  provides motive fluid to inlet valve  38   a  via actuator line  28   a  to cause inlet valve  38   a  to shift to the open positon. With outlet valve  38   b  closed, low pressure hose  22   a  is isolated from regulator pump  16   a  such that any internal pressure within regulator pump  16   a  has no effect on the downstream pressure. With inlet valve  38   a  in the open position, the upstream fluid pressure generated by material supply  14  drives the fluid within high pressure hose  24   a  into regulator pump  16   a  through inlet valve  38   a.    
     Regulator pump  16   a  fills with material from high pressure hose  24   a.  Status sensor  40  can sense when the volume of material in regulator pump  16  has reached the maximum volume, and status sensor  40  can generate a first pump full signal in response thereto. In some examples, inlet valve  38   a  can shift to the closed position in response to the pump full signal. For example, controller  12  can generate a first pump full command based on the first pump full signal and can provide the first pump full command to actuator  20  via communication link  26   a.  Based on the first pump full signal, actuator  20  can cause inlet valve  38   a  to shift to the closed position, thereby isolating the material in regulator pump  16  from the upstream pressure. In other examples, inlet valve  38   a  can remain in the open position until controller  12  generates a second dispense command, such as in response to a second fill signal generated by status sensor  40   b.  The first pump full signal indicates that regulator pump  16   a  has completed the refill cycle and is primed for a dispense cycle. 
     Regulator pump  16   b  continues through the dispense cycle and provides material to applicators  18 . When status sensor  40   b  senses that the volume of material in regulator pump  16   b  reaches the refill volume, status sensor  40   b  generates the second fill signal and provides the second fill signal to controller  12  via communication link  26   c.  In response to the second fill signal, controller  12  generates the second dispense command and a second fill command. Controller  12  can communicate the second dispense command and the second fill command to actuator  20 . It is understood, however, that controller  12  can communicate directly with regulator pump  16   b  and with regulator pump  16   a  to control the opening and closing of inlet valves  38   a  and  38   c  and outlet valves  38   b  and  38   d.    
     Based on the second dispense command, regulator pump  16   a  enters the dispense cycle. Actuator  20  can cause outlet valve  38   b  to shift to an open position and can cause inlet valve  38   a  to shift to a closed position. Closing inlet valve  38   a  isolates the material within regulator pump  16  from the upstream pressure. Actuator  20  can also provide working fluid to regulator pump  16   a  via pressure line  30   a  to drive the material downstream out of regulator pump  16   a.  It is understood that outlet valve  38   b  opens only when inlet valve  38   a  is closed, thereby ensuring that the downstream pressure is independent of and unaffected by the upstream pressure. Regulator pump  16   a  is thus fluidly connected to applicators  18  and can generate and provide the downstream pressure. 
     Based on the second fill command, regulator pump  16   b  enters the refill cycle. Actuator  20  causes outlet valve  38   d  to shift to the closed position, and causes inlet valve  38   c  to shift to the open position. With outlet valve  38   d  closed, regulator pump  16   b  is fluidly disconnected from applicators  18  such that any change in the pressure within regulator pump  16   b  has no effect on the downstream pressure in low pressure hose  22   b  and/or at applicators  18 . With inlet valve  38   c  open, the upstream fluid pressure within high pressure hose  24   b  drives the material into regulator pump  16   b  through inlet valve  38   c.  Regulator pump  16   b  fills with the material and status sensor  40   b  can generate a second pump full signal in response to sensing the volume of material within regulator pump  16   b  reaching a maximum volume. The second pump full signal indicates that regulator pump  16   b  has completed the refill cycle and is primed for another dispense cycle. 
     Regulator pump  16   a  continues to provide material to applicators  18  at the desired downstream pressure until regulator pump  16   a  requires refill. Regulator pump  16   a  is connected to applicators  18  when regulator pump  16   b  becomes empty, and regulator pump  16   b  is connected to applicators  18  when regulator pump  16   a  becomes empty. As regulator pump  16   a  proceeds through the dispense cycle, regulator pump  16   b  proceeds through the refill cycle. As regulator pump  16   b  proceeds through the dispense cycle, regulator pump  16   a  proceeds through the refill cycle. As such, the material is continuously supplied to applicators  18  by at least one of regulator pump  16   a  and regulator pump  16   b,  while the other of regulator pump  16   a  and regulator pump  16   b  is refilled, thereby ensuring a continuous flow of material to applicators  18 . 
     Flow regulating system  10 ″ provides significant advantages. Outlet valves  38   b  and  38   d  are configured to open only when inlet valves  38   a  and  38   c,  respectively, are closed, thereby isolating the downstream fluid pressure from the upstream fluid pressure. As such, the downstream fluid pressure is unaffected by the upstream fluid pressure. Regulator pumps  16   a  and  16   b  are controlled to generate the desired downstream fluid pressure. By isolating the downstream fluid pressure from the upstream fluid pressure, material supply  14  can provide the material through high pressure hoses  24   a  and  24   b  at any pressure and/or flow rate required to maintain the material properties and the desired mix ratio, where the material is a plural component material. Regulator pumps  16   a  and  16   b  individually drive the material downstream and generate the downstream fluid pressure. As such, the material can be provided at any desired downstream pressure, independent of the upstream pressure. Flow regulating system  10 ′ enables material supply  14  to provide material at high flow rates and mix ratios, while the material is provided to applicators  18  at relatively low flow rates and pressures. In addition, controlling regulator pumps  16   a  and  16   b  such that one of regulator pumps  16   a  and  16   b  dispenses the material while the other of regulator pumps  16   a  and  16   b  refills with the material ensures that a continuous supply of the material is provided to applicators  18 , thereby providing for more efficient and cost-effective material application. 
       FIG. 4  is a schematic block diagram of flow regulating system  10 ′″. Flow regulating system  10 ′″ includes material supply  14 , regulator pump  16   a,  regulator pump  16   b,  applicators  18 , and actuator  20 . Regulator pump  16   a  includes inlet valve  38   a,  outlet valve  38   b,  and status sensor  40   a.  Regulator pump  16   b  includes inlet valve  38   c,  outlet valve  38   d,  and status sensor  40   b.    
     Inlet valve  38   a  is disposed on regulator pump  16   a  and controls a flow of material into regulator pump  16   a.  Outlet valve  38   b  is disposed on regulator pump  16   a  and controls a flow of material out of regulator pump  16   a.  High pressure hose  24   a  extends between and connects material supply  14  and inlet valve  38   a.  Low pressure hose  22   a  extends between and connects outlet valve  38   b  and applicators  18 . Status sensor  40   a  is disposed on regulator pump  16   a  and is configured to monitor regulator pump  16   a.  Status sensor  40   a  is configured to communicate with actuator  20  via communication link  26   b.    
     Inlet valve  38   c  is disposed on regulator pump  16   b  and controls a flow of material into regulator pump  16   b.  Outlet valve  38   d  is disposed on regulator pump  16   b  and controls a flow of material out of regulator pump  16   b.  High pressure hose  24   b  extends between and connects material supply  14  and inlet valve  38   c.  Low pressure hose  22   b  extends between and connects outlet valve  38   d  and applicators  18 . Status sensor  40   b  is disposed on regulator pump  16   b  and is configured to monitor regulator pump  16   b.  Status sensor  40   b  is configured to communicate with actuator  20  via communication link  26   c,  which can be any suitable link for providing signals to actuator  20 , such as a wired, wireless, or pneumatic connection, among others. 
     Actuator  20  is connected to inlet valve  38   a  via actuator line  28   a,  to outlet valve  38   b  via actuator line  28   b,  to inlet valve  38   c  via actuator line  28   c,  and to outlet valve  38   d  via actuator line  28   d.  Actuator  20  is configured to provide motive fluid, such as air or non-compressible hydraulic fluid, to inlet valves  38   a  and  38   c  and to outlet valves  38   b  and  38   d  to cause inlet valves  38   a  and  38   c  and outlet valves  38   b  and  38   d  to shift between a closed position and an open position. Actuator  20  is connected to regulator pump  16   a  via pressure line  30   a  and to regulator pump  16   b  via pressure line  30   b.    
     During operation, one of regulator pump  16   a  and regulator pump  16   b  is configured to proceed through a fill cycle while the other of regulator pump  16   a  and regulator pump  16   b  proceeds through a dispense cycle. Status sensor  40   a  senses when regulator pump  16   a  has reached a refill level and generates a first fill signal in response thereto. Status sensor  40   a  provides the first fill signal to actuator  20  via communication link  26   b,  which can be any suitable link for providing signals to actuator  20 , such as a wired, wireless, or pneumatic connection, among others. The first fill signal can function as a first fill command and as a first dispense command. As such, in response to the first fill signal, actuator  20  shifts outlet valve  38   b  to a closed position and shifts inlet valve  38   a  to an open position. With outlet valve  38   b  in the closed position, the material in regulator pump  16   a  is isolated from low pressure hose  22   a  and applicators  18 . With inlet valve  38   a  in the open position, regulator pump  16   a  fills with material from high pressure hose  24   a.  Further in response to the first fill signal, actuator  20  shifts inlet valve  38   c  to the closed position and shifts outlet valve  38   d  to the open position. With inlet valve  38   c  closed, the material within regulator pump  16   b  is isolated from the upstream fluid pressure in high pressure hose  24   b.  With outlet valve  38   d  open, the material within regulator pump  16   b  is connected to applicators  18  via low pressure hose  22   b.  For example, actuator  20  can include valving configured to simultaneously open inlet valve  38   a  and outlet valve  38   d,  and to simultaneously close inlet valve  38   c  and outlet valve  38   b,  such that at least one of regulator pump  16   a  and regulator pump  16   b  is connected to applicators  18 . 
     Actuator  20  also provides working fluid to regulator pump  16   b  at a pressure required to drive the material out of regulator pump  16   b  at the desired downstream pressure and flow rate. The working fluid drives a fluid displacement member within regulator pump  16   b  through a pressure stroke, and the fluid displacement member drives the material out of regulator pump  16   b.  Regulator pump  16   b  continues through the dispense cycle until status sensor  40   b  senses that a volume of material in regulator pump  16   b  reaches a refill level and generates a second fill signal. 
     The second fill signal can function as both a second fill command and a second dispense command. As such, based on the second fill signal, actuator  20  can cause outlet valve  38   b  to shift to the open position, inlet valve  38   a  to shift to the closed position, outlet valve  38   d  to shift to the closed position, and inlet valve  38   c  to shift to the open position. Regulator pump  16   a  is thus fluidly connected to applicators  18 , and can proceed through the dispense cycle, and regulator pump  16   b  is fluidly connected to material supply  14  and can proceed through the refill cycle. 
     Actuator  20  can also provide working fluid to regulator pump  16   a  at a pressure required to drive the material out of regulator pump  16   a  at the desired downstream pressure and flow rate. The working fluid drives a fluid displacement member within regulator pump  16   a  through a pressure stroke, and the fluid displacement member drives the material out of regulator pump  16   a.  Regulator pump  16   a  continues through the dispense cycle until status sensor  40   a  senses that a volume of material in regulator pump  16   a  reaches a refill level and generates the first fill signal. 
     Flow regulating system  10 ′″ provides significant advantages. Status sensors  40   a  and  40   b  can provides signals directly to actuator  20  to cause actuator  20  initiate the refill cycles and the dispense cycles. As such, regulator pumps  16   a  and  16   b  can automatically proceed through refill and dispense cycles. Regulator pumps  16   a  and  16   b  fully isolate the downstream pressure within low pressure hoses  22   a  and  22   b  from the upstream pressure within high pressure hoses  24   a  and  24   b  such that the downstream pressure is unaffected by the upstream pressure. Isolating the upstream pressure from the downstream pressure allows the material to be applied from regulator pumps  16   a  and  16   b  at low flow rates, such as about 0.03-0.07 fl. oz/min. (1-2 cc/min.), while being supplied to regulator pumps  16   a  and  16   b  at relatively high flow rates, such as about 0.4 fl.oz/min. (12 cc/min.) or higher. Moreover, where regulator pumps  16   a  and  16   b,  including inlet valves  38   a  and  38   c  and outlet valves  38   b  and  38   d,  are pneumatically controlled, such as by actuator  20 , flow regulating system  10  can be utilized in Class I, Division I, hazardous locations. Moreover, regulator pump  16   a  is connected to applicators  18  when regulator pump  16   b  becomes empty, and regulator pump  16   b  is connected to applicators  18  when regulator pump  16   a  becomes empty. As regulator pump  16   a  proceeds through the dispense cycle, regulator pump  16   b  proceeds through the refill cycle. As regulator pump  16   b  proceeds through the dispense cycle, regulator pump  16   a  proceeds through the refill cycle. As such, the material is continuously supplied to applicators  18  by at least one of regulator pump  16   a  and regulator pump  16   b,  while the other of regulator pump  16   a  and regulator pump  16   b  is refilled, thereby ensuring a continuous flow of material to applicators  18 . 
     FIG. 5  is an isometric view of regulator pump  16 .  FIG. 5B  is a cross-sectional view of regulator pump  16  taken along line B-B in  FIG. 5A .  FIGS. 5A-5B  will be discussed together. Regulator pump  16  includes inlet valve  38   a,  outlet valve  38   b,  status sensor  40 , fluid displacement member  42 , body  44 , cover plate  46 , material chamber  48 , and working fluid chamber  50 . Inlet valve  38   a  includes wet portion  52   a,  dry portion  54   a,  seat  56   a,  stem  58   a,  sealing member  60   a,  spring  62   a,  and connector  64   a.  Outlet valve  38   b  similarly includes wet portion  52   b,  dry portion  54   b,  seat  56   b,  stem  58   b,  sealing member  60   b,  spring  62   b,  and connector  64   b.  Status sensor  40  includes slide  66 , stop  68 , and port  70 . Fluid displacement member  42  includes shaft  72  and diaphragm  74 . Body  44  includes working fluid inlet  76  and shaft bore  78 . Cover plate  46  includes material inlet  80  and material outlet  82 . 
     Cover plate  46  is attached to body  44 , and diaphragm  74  is disposed between cover plate  46  and body  44 . Material chamber  48  is disposed between and defined by cover plate  46  and diaphragm  74 . Working fluid chamber  50  is disposed between and defined by body  44  and diaphragm  74 . Working fluid inlet  76  extends through body  44  and is connected to working fluid chamber  50 . Pressure line  30  is connected to working fluid inlet  76 . Working fluid inlet  76  is configured to receive a working fluid, such as air or a non-compressible hydraulic fluid, through pressure line  30  from a fluid source, such as actuator  20  (shown in  FIGS. 1-2 ), to drive fluid displacement member  42  in a forward direction towards cover plate  46 . 
     Shaft  72  is attached to and follows diaphragm  74 , and shaft  72  extends through shaft bore  78  in body  44 . Status sensor  40  is attached to body  44  opposite working fluid chamber  50 . Slide  66  is disposed in status sensor  40  and abuts a distal end of shaft  72 . Stop  68  delimits an extent of travel for slide  66 . Port  70  is configured to receive a communication link, such as communication link  26  ( FIGS. 1-2 ), to provide information to controller  12  (shown in  FIGS. 1 and 3 ) and or actuator  20  (shown in  FIGS. 1-4 ) regarding the volume of material in material chamber  48 . Status sensor  40  is configured to provide information regarding the linear displacement of slide  66 , which corresponds to the displacement of fluid displacement member  42 , due to the connection of shaft  72  and slide  66 , and thus to the volume of material in material chamber  48 . As such, status sensor  40  can be a linear transducer. It is understood, however, that status sensor  40  can be any suitable transducer for sensing the position of fluid displacement member  42 . 
     Inlet valve  38   a  is attached to cover plate  46  at material inlet  80 . Seat  56   a  is disposed between wet portion  52   a  and cover plate  46   a.  Stem  58   a  extends from wet portion  52   a  and into dry portion  54   a.  Sealing member  60   a  is attached to stem  58   a  in wet portion  52   a  and is disposed adjacent seat  56   a.  Sealing member  60   a  is configured to engage with seat  56   a  when inlet valve  38   a  is in a closed position and is configured to be displaced from seat  56   a,  creating an inlet flow path, when inlet valve  38   a  is in an open position. Connector  64   a  extends from dry portion  54   a  and is configured to be connected to an actuator line, such as actuator line  28   a  (best seen in  FIG. 1 ). Connector  64   a  receives motive fluid, such as air or a non-compressible hydraulic fluid, and provides the motive fluid to and vents the motive fluid from dry portion  54   a  to drive stem  58   a  and sealing member  60   a  between the closed position and the open position. Spring  62   a  is disposed in dry portion  54   a  and is configured to drive stem  58   a  and sealing member  60   a  to the closed position when a supply of motive fluid is removed from dry portion  54   a.  While inlet valve  38   a  is shown as a needle valve, it is understood that inlet valve  38   a  can be any desired valve capable of being controlled between the open position and the closed position. 
     Outlet valve  38   b  is attached to cover plate  46  at material outlet  82 . Seat  56   b  is disposed between wet portion  52   b  and cover plate  46   b.  Stem  58   b  extends from wet portion  52   b  and into dry portion  54   b,  and sealing member  60   b  is attached to stem  58   b  and disposed adjacent seat  56   b.  Sealing member  60   b  is configured to engage with seat  56   b  when outlet valve  38   b  is in a closed position and is configured to be displaced from seat  56   b  when outlet valve  38   b  is in an open position. Connector  64   b  extends from dry portion  54   b  and is configured to be connected to an actuator line, such as actuator line  28   b  (best seen in  FIG. 1 ). Connector  64   b  can provide motive fluid to dry portion  54   b  to drive stem  58   b  and sealing member  60   b  to the open position. Spring  62   b  is disposed in dry portion  54   b  and can drive stem  58   b  and sealing member  60   b  to the closed position when the motive fluid is vented from dry portion  54   b.  While outlet valve  38   b  is shown as a needle valve, it is understood that inlet valve  38   a  can be any desired valve capable of being specifically controlled between the open position and the closed position. 
     In some examples, outlet valve  38   b  is identical to inlet valve  38   a,  except outlet valve  38   b  is connected to material outlet  82 , such that wet portion  52   b  receives material from material chamber  48 , and inlet valve  38   a  is connected to material inlet  80 , such that wet portion  52   a  provides material to material chamber  48 . While outlet valve  38   b  and inlet valve  38   a  can be identical, thereby facilitating easy replacement of parts while requiring fewer unique parts, it is understood that each of inlet valve  38   a  and outlet valve  38   b  can be of any desired configuration and can be identical or unique. 
     During a refill cycle, motive fluid can be provided to dry portion  54   a  of inlet valve  38   a,  thereby causing stem  58   a  and sealing member  60   a  to shift away from seat  56 a. Motive fluid can be vented from dry portion  54   b  of outlet valve  38   b  and outlet valve  38   b  shifts to the closed positon. Outlet valve  38   b  remains closed when inlet valve  38   a  is open. The motive fluid shifts stem  58   a  causing sealing member  60   a  to disengage from seat  56   a,  thereby creating the inlet flowpath between sealing member  60   a  and seat  56   a.  An upstream pressure generated by a material supply, such as material supply  14  (shown in  FIGS. 1-4 ), causes material to flow into material chamber  48  through inlet valve  38   a  and material inlet  80 . The material flowing into material chamber  48  causes fluid displacement member  42  to shift rearward as material chamber  48  expands, thereby driving shaft  72  rearward due to the connection of shaft  72  and diaphragm. Shaft  72  simultaneously drives slide  66  rearward. Shaft  72  and slide  66  continue to shift until slide  66  abuts stop  68 , which delimits an extent of travel for slide  66  in the rearward direction. Status sensor  40  can be configured to generate the pump full signal in response to slide  66  abutting stop  68 . Status sensor  40  can provide the pump full signal to the controller to indicate the regulator pump  16  has completed the refill cycle and is primed to for a dispense cycle. Regulator pump  16  can remain in the primed state until a dispense command is received. 
     Based on the dispense command, regulator pump  16  can enter a dispense cycle. Inlet valve  38   a  shifts to the closed position and the outlet valve  38   b  shifts to the open position. For example, the actuator can provide a supply of motive fluid to dry portion  54   b  of outlet valve  38   b,  causing stem  58   b  and sealing member  60   b  to shift to an open position. In the open position sealing member  60   b  is displaced from seat  56   b  such that material can flow out of material chamber  48  between sealing member  60   b  and seat  56   b.  The actuator can also vent motive fluid from dry portion  54   a  of inlet valve  38   a,  and spring  62   a  can thus drive stem  58   a  and sealing member  60   a  to the closed position. With inlet valve  38   a  closed, the internal pressure in material chamber  48  and the downstream pressure are isolated from the upstream pressure. 
     To generate a desired downstream pressure working fluid is provided to working fluid chamber  50  through working fluid inlet  76 . Pressure line  30  receives working fluid from a working fluid source, such as actuator  20  (shown in  FIGS. 1-4 ), and provides the working fluid to working fluid chamber  50 . The working fluid drives fluid displacement member  42  in the forward direction through material chamber  48 . The pressure of the working fluid in working fluid chamber  50  is directly related to the material pressure in material chamber  48  and thus to the downstream pressure. As such, the downstream pressure is generated by regulator pump  16  and can be controlled by controlling the working fluid pressure. In the example shown, the working fluid pressure and the downstream pressure have a 1:1 pressure ratio. For example, where the desired downstream fluid pressure is 1034 KPa (148 psi), the working fluid within pressure chamber will be provided at and maintained at 1034 KPa (148 psi). 
     The working fluid drives fluid displacement member  42  in the forward direction. Diaphragm  74  pulls shaft  72  through shaft bore  78  due to the connection of shaft  72  and diaphragm  74 . Shaft  72  simultaneously pulls slide  66  in the forward direction due to the connection of shaft  72  and slide  66 . Status sensor  40  transmits positional information related to fluid displacement member  42  based on the position of slide  66 . When slide reaches a forward extent of travel, indicating that the volume of material in material chamber  48  has reached the refill volume, status sensor  40  can generate the fill signal and transmit the fill signal to controller  12 . While status sensor  40  is described as generating the fill signal when slide  66  reaches the forward extent of travel, it is understood that status sensor  40  can continuously provide positional information to the controller such that the controller provides the fill command based on slide  66  reaching any desired position. For example, the controller can generate the fill command based on slide  66  being at a position indicating that material chamber  48  is 50% empty. The fill signal indicates that regulator pump  16  has is ready to proceed through another refill cycle. 
     Regulator pump  16  provides significant advantages. Outlet valve  38   b  of regulator pump  16  is configured to be in the closed position whenever inlet valve  38   a  of regulator pump is in the open position. As such, the upstream fluid pressure has no effect on the downstream fluid pressure downstream of outlet valve. By isolating the downstream fluid pressure from the upstream fluid pressure, the downstream fluid pressure can be specifically controlled to provide whatever pressure or flow rate is desired. Isolating the downstream fluid pressure from the upstream fluid pressure allows for high flow rates and pressures upstream of regulator pump  16 , which can ensure that the material has desired properties, while providing low flow rates and pressures downstream of regulator pump  16  where the material is applied. 
       FIG. 6A  is an isometric view of regulator pump  16 ′.  FIG. 6B  is a cross-sectional view of regulator pump  16 ′ taken along line B-B in  FIG. 6A .  FIG. 6C  is a cross-sectional view of regulator pump  16 ′ taken along line C-C in  FIG. 6A .  FIG. 6D  is a cross-sectional view of regulator pump  16 ′ taken along line D-D in  FIG. 6A .  FIGS. 6A-6D  will be discussed together. Regulator pump  16 ′ includes inlet valve  38   a,  outlet valve  38   b,  status sensor  40 ′, fluid displacement member  42 , body  44 ′, cover plate  46 ′, material chamber  48 , working fluid chamber  50 , base  84 , pilot valve  86 , and pressure source  88 . Fluid displacement member  42  includes shaft  72 ′, diaphragm  74 , and diaphragm plate  90 . Shaft  72 ′ includes step  92 . Body  44 ′ includes working fluid inlet  76 , shaft bore  78 , signal passage  94 , status sensor port  96 , and pressure port  98 . 
     Cover plate  46 ′ and body  44 ′ are disposed on base  84 . Cover plate  46 ′ is attached to body  44 ′ with diaphragm  74  disposed between and secured between cover plate  46 ′ and body  44 ′. Shaft  72 ′ is attached to and follows diaphragm  74 , and shaft  72 ′ extends rearward from diaphragm  74  through shaft bore  78 . Diaphragm plate  90  is attached to diaphragm  74  and configured to contact and drive pin  100  of pilot valve  86 . O-ring  102  is disposed in shaft bore  78  and provides a seal around shaft  72 ′. Material chamber  48  is disposed between and defined by cover plate  46 ′ and diaphragm  74 . Working fluid chamber  50  is disposed between and defined by body  44 ′ and diaphragm  74 . Working fluid inlet  76  extends through body and is connected to working fluid chamber  50 . Working fluid inlet  76  is configured to receive a working fluid, such as air or a non-compressible hydraulic fluid, through pressure line  30  and to provide the working fluid to working fluid chamber  50 . The working fluid is configured to pressurize working fluid chamber  50  and to drive fluid displacement member  42  through a pressure stroke, during which fluid displacement member  42  is driven towards cover plate  46 ′ to drives material out of material chamber  48  through outlet valve  38   b.  Inlet valve  38   a  is attached to base  84 , and outlet valve  38   b  is similarly attached to base  84 . Inlet valve  38   a  is fluidly connected to material chamber  48  by a material passage (not shown) extending through base  84 , and outlet valve  38   b  is similarly connected to material chamber  48  by a material passage (not shown) extending through base  84 . Inlet valve  38   a  and outlet valve  38   b  can be of any suitable configuration for controlling the flow of material through regulator pump  16  such that the downstream pressure is isolated form and independent of the upstream pressure. 
     Status sensor port  96  extends into body  44 ′ and receives status sensor  40 ′. Status sensor  40 ′ is configured to communicate a status of regulator pump  16 , such as whether regulator pump  16  requires a refill or is ready to dispense material, to a controller, such as controller  12  (shown in  FIGS. 1 and 3 ), and/or an actuator, such as actuator  20  (shown in  FIGS. 1-4 ). Signal passage  94  extends from status sensor port  96  and to shaft bore  78 . Pilot valve  86  is disposed in body  44 ′ between status sensor port  96  and shaft bore  78 , such that signal passage  94  can receive fluid, such as air, through pilot valve  86 . Pin  100  of pilot valve  86  extends through body  44 ′ and into working fluid chamber  50 . Pressure source  88  is disposed in pressure port  98  and is configured to provide pressurized fluid, such as compressed air, to pilot valve  86 . Pressure source  88  is configured to continuously supply pressurized fluid through pressure port  98 . When pilot valve  86  is in a rearward, open position, the pressurized fluid flows through pilot valve  86  and into signal passage  94 . When pilot valve is in a forward, closed position, the pressurized fluid is prevented from flowing through pilot valve  86 , such that the pressurized fluid cannot flow to signal passage  94 . 
     During operation, fluid displacement member  42  is alternatively driven in a forward direction towards cover plate to displace material from material chamber  48  and in a rearward direction away from cover plate by the material as the material flows into material chamber  48  through inlet valve  38   a.  By way of example, a refill cycle and a dispense cycle are discussed below. 
     The controller and/or the actuator can receive a fill signal from status sensor  40 ′ and generate a fill command. Based on the fill command, outlet valve  38   b  shifts to the closed position, preventing material from flowing downstream out of material chamber  48 , and inlet valve  38   a  shifts to the open position, allowing material to flow into material chamber  48  through inlet valve  38   a.  With inlet valve  38   a  in the open position, the upstream fluid pressure generated by a material supply, such as material supply  14  (shown in  FIGS. 1-4 ), drives the material into material chamber  48 . The material flowing into material chamber  48  drives fluid displacement member  42  in the rearward direction. 
     Fluid displacement member  42  continues in the rearward direction and diaphragm plate  90  contacts pin  100  of pilot valve  86 . As fluid displacement member  42  is driven in the rearward direction, step  92  passes o-ring  102  such that o-ring  102  seals against shaft  72 . With o-ring  102  contacting shaft  72 ′, shaft bore  78  is sealed such that signal passage  94  cannot vent through shaft bore  78 . Diaphragm plate  90  drives pin  100  causing the internal components of pilot valve  86  to shift rearward, thereby causing pilot valve  86  to shift to the open position. With pilot valve  86  open, the pressurized fluid provided by pressure source  88  can flow through pilot valve to signal passage  94 . The pressure within signal passage  94  suddenly rises when pilot valve  86  shifts to the open position. Status sensor  40 ′ senses the sudden rise in pressure in signal passage  94  and is configured to generate a pump full signal in response to the sudden rise in pressure and to provide the pump full signal to the controller and/or the actuator. While status sensor  40 ′ is described as a pressure transducer, it is understood that any suitable sensor can be utilized. The pump full signal indicates that regulator pump  16  has completed the refill cycle and is primed for the dispense cycle. 
     When a dispense command is generated, outlet valve  38   b  shifts to the open position and inlet valve  38   a  shifts to the closed position based on the dispense command. Material chamber  48  is thus isolated from the upstream pressure and fluidly connected to the downstream pressure. With outlet valve  38   b  open, working fluid is provided to working fluid chamber  50 , for example by a working fluid source, such as the actuator, to drive fluid displacement member  42  in the forward direction. In some examples, the pressure in working fluid chamber  50  and the downstream pressure generated by fluid displacement member  42  have a 1:1 pressure ratio. As such, the downstream pressure can be controlled by setting the working fluid pressure at the desired downstream pressure. 
     During the dispense cycle, diaphragm  74  pulls shaft  72 ′ in the forward direction as the working fluid drives fluid displacement member  42  in the forward direction. When step  92  of shaft  72 ′ is pulled beyond o-ring  102 , signal passage  94  is unsealed and can vent the pressurized fluid through shaft bore  78 . Step  92  can be disposed at any desired position on shaft  72 ′ to control when signal passage  94  vents through shaft bore  78 . For example, step  92  can be positioned on shaft  72 ′ such that signal passage  94  vents when material chamber  48  is empty. In other examples, step  92  can be positioned to vent signal passage  94  after any desired volume and/or percentage of material has been displaced from material chamber  48 . 
     Venting signal passage  94  causes the pressure within signal passage  94  to drop to the ambient. The drop in pressure causes pilot valve  86  to shift to the closed position such that the pressurized fluid provided through pressure port  98  cannot flow to signal passage  94 . Status sensor  40 ′ senses the drop of pressure within signal passage  94  and generates a fill signal in response to the drop in pressure. The fill signal indicates that regulator pump  16 ′ has completed the dispense cycle and is ready to proceed through another refill cycle. 
     Regulator pump  16 ′ provides significant advantages. Regulator pump  16 ′ generates the fill signal and the pump full signal in a pneumatic-mechanical manner. Regulator pump  16  is thus suitable for use in Class I, Division I hazardous locations. Regulator pump  16 ′ is a self-contained unit that generates the downstream fluid pressure. Regulator pump  16 ′ also fully isolates the downstream fluid pressure from the upstream fluid pressure such that the downstream fluid pressure remains independent from and unaffected by the upstream fluid pressure. As such, regulator pump  16 ′ can provide materials downstream flow rates and pressures well below the minimum flow rates and pressures required at the material supply. Regulator pump  16 ′ thus allows for more and varied materials to be applied at low flow rates and pressures. Inlet valve  38   a  and outlet valve  38   b  can be identical parts, saving costs and maintenance overhead by reducing the amount of part numbers. 
       FIG. 7A  is a flow chart depicting refill cycle  104 .  FIG. 7B  is a flow chart depicting dispense cycle  106 .  FIGS. 7A and 7B  will be discussed together. In step  108 , a fill signal is generated. The fill signal can be generated based on a volume of material displaced from a regulator pump, such as regulator pump  16  ( FIGS. 1-4 ). In some examples, a sensor, such as status sensor  40  (best seen in  FIGS. 1-4 ), can sense when the regulator pump is ready to begin a refill cycle. For example, the status sensor can sense when the volume of material in the regulator pump reaches a minimum volume, and can generate the fill signal in response to the volume of material reaching the minimum volume. Any suitable sensor can be utilized for sensing when regulator pump requires a refill, such as linear, pressure, temperature, and/or flow rate transducers. In some examples, the fill signal can be provided to a controller, such as controller  12  (shown in  FIGS. 1 and 3 ), and the controller can generate a fill command based on the fill signal. In other examples, the fill signal can be provided to an actuator, such as actuator  20  (shown in  FIGS. 2 and 4 ), to cause the actuator to initiate the refill cycle. In such a case, the fill signal is the fill command. 
     In step  110 , a downstream material is fluidly isolated from the regulator pump. To isolate the downstream material an outlet valve, such as outlet valve  38   b  ( FIGS. 1-6A ), is shifted to a closed position. In some examples, the controller can cause the outlet valve to shift to the closed position. For example, the controller can generate the fill command based on the fill signal and can provide the fill command to an actuator. The actuator can actuate the outlet valve to the closed position by venting or providing motive fluid to the outlet valve, for example. In other examples, where the fill signal is provided directly to the actuator, the fill signal can function as the fill command and can cause the actuator to shift the outlet valve to the closed position. For example, the fill signal can cause a three-way valve connected to the outlet valve and to an inlet valve, such as inlet valve  38   a  ( FIGS. 1-6A ), to cause the three-way valve to shift positions, thereby causing the outlet valve to shift closed. 
     In step  112 , an upstream material is fluidly connected to the regulator pump. The inlet valve is shifted to an open position in response to the fill command. It is understood, however, that the inlet valve opens only when the outlet valve closes. As such, the downstream material remains isolated from the upstream material such that the upstream pressure has no effect on the downstream pressure. In some examples, the controller can generate the fill command based on the fill signal and can provide the fill command to an actuator. The actuator can actuate the inlet valve to the open position. For example, the actuator can provide motive fluid, such as compressed air or hydraulic fluid, to or vent motive fluid from the inlet valve. In other examples, where the fill signal is provided directly to the actuator, the fill signal can function as the fill command, such that the actuator actuates the inlet valve to the open position based on the fill signal. For example, the fill signal can cause a three-way valve connected to the outlet valve and to an inlet valve to shift positions, thereby causing the inlet valve to actuate from the closed position to the open position. 
     In step  114 , a pump full signal is generated. The status sensor can sense when the volume of material in fluid chamber has reached a material capacity and can generate the pump full signal in response to the material in fluid chamber reaching the material capacity. The pump full signal can be provided to the controller, and the pump full signal indicates that the regulator pump has completed the refill cycle and is primed for a dispense cycle. 
     In step  116 , of  FIG. 7B , a dispense command is generated. The dispense command causes the regulator pump to enter the dispense cycle, where the regulator pump is fluidly connected to the downstream material and fluidly disconnected from the upstream material. 
     In some examples, such as flow regulating systems with multiple regulator pumps, such as flow regulating system  10 ″ ( FIG. 3 ) and flow regulating system  10 ′″ ( FIG. 4 ), the dispense command can be generated based on a first fill signal from a first regulator pump. The controller can generate a first dispense command based on the first fill signal, and the first dispense command can cause a second regulator pump, which has already completed a fill cycle, to enter the dispense cycle. As such, one of the regulator pumps is fluidly connected downstream and providing material downstream while the other of the regulator pumps is fluidly connected upstream and refilling with material for the next dispense cycle. The flow regulating system is configured such that at least one of the regulator pumps is fluidly connected downstream to ensure a continuous downstream supply of material. 
     In other examples, the controller can generate the dispense command based on the pump full signal. For example, the regulator pump can enter the refill cycle when the material is deadheaded, such as where downstream applicators are between application cycles, and can begin the dispense cycle immediately after completing the refill cycle based on the pump full command, such that the regulator pump is fluidly connected to the applicators before the next application cycle. In additional examples, the pump full signal can function as the dispense command, such as where the pump full signal is provided directly to the actuator to cause the actuator to actuate the inlet valve and the outlet valve. 
     In step  118 , the upstream material is fluidly isolated from the regulator pump. For example, the inlet valve can shift to the closed position based on the dispense command. In some examples, the controller can provide the dispense command to the actuator to cause the actuator to provide motive fluid to or vent motive fluid from the inlet valve to cause the inlet valve to shift to the closed position. In other examples, such as where the pump full signal is provided directly to the actuator, the pump full signal can function as the dispense command, such that the actuator shifts the inlet valve to the closed position based on the pump full signal. For example, the fill signal can cause a three-way valve connected to the outlet valve and to an inlet valve to shift positions, thereby causing the inlet valve to shift from the open position to the closed position. 
     In step  120 , the downstream material is fluidly connected to the regulator pump. For example, the outlet valve can shift to the open position in response to the dispense command. In some examples, the controller can provide the dispense command to the actuator to cause the actuator to provide motive fluid to or vent motive fluid from the outlet valve to cause the outlet valve to shift to the open position. In other examples, such as where the pump full signal is provided directly to the actuator, the pump full signal can function as the dispense command, such that the actuator shifts the outlet valve to the open position based on the pump full signal. For example, the fill signal can cause a three-way valve connected to the outlet valve and to an inlet valve to shift positions, thereby causing the outlet valve to shift from the closed position to the open position. The downstream material is fluidly connected to the regulator pump only where the upstream material is fluidly isolated from the regulator pump, such that the upstream pressure has no effect on the downstream pressure 
     In step  122 , the regulator pump drives the material downstream at a desired downstream pressure. For example, a fluid displacement member, such as fluid displacement member  42  (best seen in  FIGS. 5B and 6C ), can be driven through a pressure stroke to drive the material downstream from the regulator pump. In some examples, the controller and/or the actuator can electrically drive the fluid displacement member, such as by powering a solenoid attached to and driving the fluid displacement member. In other examples, the actuator can provide a working fluid, such as compressed air or a non-compressible hydraulic fluid, to the regulator pump to drive the fluid displacement member. The regulator pump is controlled to produce a desired downstream pressure and/or flow rate. In some examples, the regulator pump is configured to provide a 1:1 pressure ratio between the working fluid and the downstream pressure. As such, the downstream pressure can be controlled by controlling the working fluid pressure driving the fluid displacement member. The regulator pump continues to dispense the material until the regulator pump requires a refill, at which point the regulator pump is ready for another refill cycle and the process proceeds back to step  108 . 
     The outlet valve of the regulator pump is configured to be in the closed position whenever the inlet valve is in the open position. As such, the upstream pressure has no effect on the downstream pressure. By isolating the downstream pressure from the upstream pressure, the downstream pressure can be specifically controlled to provide whatever pressure and/or flow rate is desired. The regulator pump generates the downstream pressure by driving the material out of the fluid chamber, such that the upstream pressure has no effect on the downstream pressure. As such, the material can be provided to the regulator pump at high flow rates and pressures while leaving the downstream pressure unaffected. 
       FIG. 8A  is a flow diagram depicting method  124  of dispensing material in a multiple regulator pump system. In step  126 , a first fill signal is generated. The first fill signal can be generated based on a volume of material displaced from a first regulator pump, such as regulator pump  16   a  ( FIGS. 2 and 4 ). In some examples, a sensor, such as status sensor  40   a  ( FIGS. 2 and 4 ), can sense when the first regulator pump is ready to begin a refill cycle. For example, the status sensor can sense when the volume of material in the first regulator pump reaches a minimum volume, and can generate the first fill signal in response to the volume of material reaching the minimum volume. Any suitable sensor can be utilized for sensing when the first regulator pump requires a refill, such as linear, pressure, temperature, and/or flow rate transducers. In some examples, the first fill signal can be provided to a controller, such as controller  12  (shown in  FIGS. 1 and 3 ), and the controller can generate a first fill command based on the first fill signal. In other examples, the first fill signal can be provided to an actuator, such as actuator  20  (shown in  FIGS. 2 and 4 ), to cause the actuator to initiate the refill cycle. Based on the first fill signal generated in step  126 , method  124  proceeds to steps  128  and  130 . 
     In step  128 , a second regulator pump, such as regulator pump  16   b  ( FIGS. 2 and 4 ) proceeds through a dispense cycle based on the first fill signal. In step  130 , a first regulator pump proceeds through a refill cycle based on the first fill signal. The second regulator pump enters the dispense cycle prior to the first regulator pump entering the refill cycle, thereby preventing any loss in pressure and/or flow to a downstream applicators. 
     In step  128 , the downstream material applicator is fluidly connected to the second regulator pump and the upstream material supply is fluidly isolated from the second regulator pump. To connect the downstream material, a second outlet valve, such as outlet valve  38   d  ( FIGS. 2 and 4 ), is shifted to an open position. To isolate the upstream material, a second inlet valve, such as inlet valve  38   c  ( FIGS. 2 and 4 ), is shifted to a closed position. It is understood, that the second inlet valve can shift to the closed position at the beginning of a dispense cycle or can shift to the closed position at the end of a previous refill cycle. The second outlet valve opens only when the second inlet valve is closed, ensuring that the upstream fluid pressure has no effect on the downstream fluid pressure. In some examples, the controller can provide a first dispense command to the actuator to cause the actuator to shift the second inlet valve to the closed position and to shift the second outlet valve to the open position. In other examples, the first fill signal can function as the first dispense command such that the actuator shifts the second inlet valve to the closed position and shifts the second outlet valve to the open position in response to the first fill signal. 
     With the second outlet valve in the open position and the second inlet valve in the closed position, the second regulator pump drives the material within the second regulator pump downstream through the second outlet valve. For example, a fluid displacement member, such as fluid displacement member  42  (best seen in  FIGS. 5B and 6C ), can be driven through a pressure stroke to drive the material downstream from the second regulator pump. In some examples, the controller and/or the actuator can electrically drive the fluid displacement member, such as by powering a solenoid attached to and driving the fluid displacement member. In other examples, the actuator can provide a working fluid, such as compressed air or a non-compressible hydraulic fluid, to the second regulator pump to drive the fluid displacement member. The second regulator pump is controlled to produce a desired downstream pressure and/or flow rate. In some examples, the second regulator pump is configured to provide a 1:1 pressure ratio between the working fluid and the downstream pressure. As such, the downstream pressure can be controlled by controlling the working fluid pressure driving the fluid displacement member. The second regulator pump continues to dispense the material until the second regulator pump requires a refill. 
     In step  130 , the downstream material applicator is fluidly isolated from the first regulator pump and an upstream material supply is fluidly connected to the first regulator pump. To isolate the downstream material, a first outlet valve, such as outlet valve  36   b  ( FIGS. 1-6A ), is shifted to a closed position. The first outlet valve can shift to the closed position after or simultaneous to the second outlet valve shifting to the open position. As such, the downstream pressure and flow are maintained because at least one of the first outlet valve and the second outlet valve is in the open position. To connect the upstream material, a first inlet valve, such as inlet valve  38   a  ( FIGS. 1-6A ) can shift to an open position. The first inlet valve opens only when the first outlet valve is closed, ensuring that the upstream fluid pressure has no effect on the downstream fluid pressure. In some examples, the controller can provide a first fill command to the actuator to cause the actuator to shift the first outlet valve to the closed position and to shift the first inlet valve to the open position. In other examples, the first fill signal can function as the first fill command such that the actuator shifts the first outlet valve to the closed position and shifts the first inlet valve to the open position in response to the first fill signal. 
     With the first inlet valve open, the upstream pressure drives the material into the first regulator pump to fill a fluid chamber of the first regulator pump. Opening the inlet valve and closing the outlet valve fully isolates the upstream material form the downstream material such that the upstream pressure has no effect on the downstream pressure. In some examples, the first inlet valve shifts to the closed position at the end of the first regulator pump refill cycle. For example, the first regulator pump can generate a first pump full signal when full, and the actuator can cause the first inlet valve to shift to the closed position based on the first pump full signal. As such, the first regulator pump can be isolated from the upstream material at the end of the first regulator pump refill cycle. The first regulator pump is thus primed for a first regulator pump dispense cycle. 
     In step  132 , a second fill signal is generated. The second fill signal can be generated based on a volume of material displaced from a second regulator pump. In some examples, a sensor, such as status sensor  40   b  ( FIGS. 2 and 4 ), can sense when the second regulator pump is ready to begin a refill cycle. For example, the status sensor can sense when the volume of material in the second regulator pump reaches a minimum volume, and can generate the first fill signal in response to the volume of material reaching the minimum volume. The second fill signal can be provided to the controller and/or to the actuator. Based on the second fill signal generated in step  132 , method  124  proceeds to steps  134  and  136 . 
     In step  134 , the first regulator pump proceeds through a dispense cycle based on the second fill signal. In step  136 , the second regulator pump proceeds through a refill cycle based on the second fill signal. The first regulator pump enters the dispense cycle prior to the second regulator pump entering the refill cycle, thereby preventing any loss in pressure and/or flow to a downstream applicators. 
     In step  134 , the first regulator pump proceeds through a dispense cycle based on the second fill signal. The actuator causes the first inlet valve to shift to the closed position, fluidly isolating the upstream material from the first regulator pump. In some examples, the first inlet valve is closed at the end of the first regulator pump refill cycle, such as in response to the first pump full signal, for example. The actuator causes the first outlet valve to shift to the open position, fluidly connecting the downstream material and the first regulator pump. With the first outlet valve in the open position and the first inlet valve in the closed position, the first regulator pump drives the material within the first regulator pump downstream through the first outlet valve. In some examples, the controller and/or the actuator can electrically drive the fluid displacement member, such as by powering a solenoid attached to and driving the fluid displacement member. In other examples, the actuator can provide a working fluid, such as compressed air or a non-compressible hydraulic fluid, to the first regulator pump to drive the fluid displacement member. The first regulator pump continues to dispense the material until the first regulator pump requires a refill. When the first regulator pump requires a refill, method  124  proceeds back to step  126 , and the first fill signal is generated. 
     In step  136 , the second regulator pump proceeds through a refill cycle based on the second fill signal. The actuator causes the second outlet valve to shift to the closed position, fluidly isolating the downstream material from the second regulator pump. The second outlet valve can shift to the closed position after or simultaneous to the first outlet valve shifting to the open position, ensuring that the downstream pressure and flow are maintained because at least one of the first outlet valve and the second outlet valve is in the open position. The actuator further causes the second inlet valve to shift to the open position, fluidly connecting the upstream material and the second regulator pump. The material flows into the second regulator pump through the second inlet valve to refill the second regulator pump with the material. In some examples, the second inlet valve shifts to the closed position at the end of the second regulator pump refill cycle. For example, the second regulator pump can generate a second pump full signal when full, and the actuator can cause the second inlet valve to shift to the closed position based on the second pump full signal. As such, the second regulator pump can be isolated from the upstream material at the end of the second regulator pump refill cycle. The second regulator pump is thus primed for a second regulator pump dispense cycle. 
     One of the first regulator pump and the second regulator pump dispenses material downstream at a desired flow rate and pressure as the other of the first regulator pump and the second regulator pump refills with the material. As such, a constant supply of the material is supplied downstream at the desired flow rate and pressure. In addition, each outlet valve is configured to be in the closed position whenever the associated inlet valve is in the open position. As such, the upstream pressure has no effect on the downstream pressure. By isolating the downstream pressure from the upstream pressure, the downstream pressure can be specifically controlled to provide whatever pressure and/or flow rate is desired. The regulator pumps generate the downstream pressure by driving the material downstream with a fluid displacement member. As such, the material can be provided to the regulator pump at high flow rates and pressures while leaving the downstream pressure unaffected. 
     While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.