Note: Descriptions are shown in the official language in which they were submitted.
CA 02882163 2015-02-18
SYSTEM FOR REGULATION AND CONTROL OF WATER PRESSURE AND
FLOW RATE IN A HIGH PRESSURE WATER APPLICATION
BACKGROUND
[0001] High pressure water applications include, but are not limited to,
operations such as
high pressure power washing and excavation. In the soil excavation process,
high pressure
water is used to loosen and excavate soil and other components while
industrial strength
vacuum is used to evacuate the debris. This process is favored when excavating
around
existing buried pipes, cables, and the like. However, it is also utilized in
potholing, slot
trenching, and other non-destructive excavations.
[0002] Because of the numerous variations of high pressure water applications,
wide ranges
of operating parameters (such as water pressure and flow rates) are required.
Operators need
to have the ability to adjust water pressure and flow rate as dictated by the
job type and job
conditions. However, water pumps currently utilized in most high pressure
water
applications have lubrication systems that require a minimum speed (e.g., rpm)
to properly
lubricate the internal components of the high pressure water pump. Further,
water flow is
proportional to the speed of the water pump.
[0003] With previous systems, if only a portion of the water flow resulting
from a particular
pump speed is utilized, a back pressure may be created and excess flow may be
returned to
the water supply tank, as necessary, via a standard safety pressure relief
valve if the back
pressure exceeds the design pressure of the safety relief valve. Thus, for a
given water pump,
this operating feature of previous systems may prevent an operator from
operating over a
wide range of flow rates at a pressure less than the system relief setting,
regardless of what a
particular job or application may require.
SUMMARY
[0004] Some embodiments of a system as described herein may provide a control
system
that senses the required flow needed (at a given pressure) for a particular
job and regulates
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excess water to flow back to the water supply tank without going through the
standard system
relief valve. Some embodiments of the present invention may allow an operator
to select the
water flow and water pressure required for a given situation over a much wider
range than
has previously been possible.
[0005] As described herein, an operator may regulate water flow from about 25
gpm (gallons
per minute) to 0 gpm, for example, at a selected pressure with one size water
pump. In the
past, the maximum/minimum flows possible were completely dependent on the
particular
size water pump utilized. For example, a 25 gpm water pump, due to minimum
speed
requirements, may have a minimum flow rate of approximately 10 gpm, for
instance. In
order to get flows down to a lower amount, such as 3-5 gpm, for instance, at
the same
pressure, a smaller water pump (e.g., a 10 gpm pump) may have been required.
Thus, in
situations where the high pressure water system is mounted on a mobile chassis
or trailer, for
example, the operator would have to change out the water pump. Embodiments of
the
present inventive system and apparatus may allow an operator with a given
water pump to
operate in multiple job conditions, because one pump can provide a wider range
of flow rates.
[0006] In some embodiments of the present inventive system, the operator may
select an
appropriate operational pressure setting and the water system may be
controlled by a
computer processor (e.g., a microprocessor) that receives pressure data from a
pressure
transducer in the high pressure water discharge line and a speed sensor at the
water pump
drive motor. A unique electro-hydraulic water (EHW) bypass valve controlled by
the
microprocessor may regulate excess water flowing back to the water supply
tank, allowing
the standard safety relief valve to remain closed during a wider range of
operating conditions.
[0007] In some embodiments, a system for regulation and control of water
pressure and flow
rate in high pressure water applications may include: a variable speed water
pump
configured for receiving water from a water reservoir; a discharge conduit
configured for
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passing water from the water pump to a nozzle; a relief valve in fluid
communication with the
discharge conduit, the relief valve having a pressure limit, wherein the
relief valve is
configured to divert water from the discharge conduit to the water reservoir
if a water
pressure in the discharge conduit exceeds the pressure limit; a variable flow
bypass valve in
fluid communication with the discharge conduit, the bypass valve being
controllable between
a closed position and a fully open position, the bypass valve being configured
to divert water
from the discharge conduit to the water reservoir when the bypass valve is in
an open
position; a speed sensor configured for sensing a speed of the water pump; a
pressure
transducer configured for sensing a pressure in the discharge conduit; and a
computer
configured for setting a preselected water pressure via an operator interface,
the preselected
water pressure being less than the pressure limit; receiving a speed input
signal from the
speed sensor; receiving a pressure input signal from the pressure transducer;
and in response
to the input signals, controlling the speed of the water pump within a range
of speeds and
controlling the bypass valve in a manner that tends to maintain the pressure
in the discharge
conduit at the preselected water pressure.
[0008] In some embodiments, the system may further include a hydraulic control
system
having: a hydraulic drive pump configured for engagement with a power takeoff
of a
vehicle; a hydraulic drive motor operatively connected to the hydraulic drive
pump, the
hydraulic drive motor being operatively engaged with the water pump; a
hydraulic controller
configured for receiving a first output signal from the computer, the
hydraulic controller
being operatively engaged with the hydraulic drive pump; and a proportional
hydraulic
pressure control valve configured for receiving a second output signal from
the computer, the
proportional hydraulic pressure control valve being operatively engaged with
the bypass
valve; wherein the hydraulic controller is configured for controlling the
speed of the water
pump via the hydraulic drive pump and the hydraulic drive motor in response to
the first
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output signal; and wherein the proportional hydraulic pressure control valve
is configured for
controlling the bypass valve in response to the second output signal. The
hydraulic control
system may further include a hydraulic charge pump operatively engaged with
the hydraulic
drive pump and in fluid communication with the hydraulic controller and the
proportional
hydraulic pressure control valve.
[0009] In some embodiments, the water pump may have a minimum speed, and the
computer may be further configured to reduce the speed of the water pump if
the pressure in
the discharge conduit is greater than the preselected water pressure and the
speed of the water
pump is greater than the minimum speed.
[00010] In some embodiments, the computer may be further configured to divert
water from
the discharge conduit through the bypass valve if the pressure in the
discharge conduit is
greater than the preselected water pressure and the speed of the water pump is
less than or
equal to the minimum speed.
[00011] In some embodiments, an electro-hydraulic water bypass valve may be
provided for
use in a system having a water pressure safety relief valve for regulation and
control of water
pressure applications. The system may include an operator interface for
setting a preselected
water pressure, a computer receiving input from a water pump speed sensor and
a water
pressure transducer, wherein output from the computer regulates a variable
displacement
hydraulic drive pump and a proportional pressure control valve. A hydrostatic
drive motor
may be operatively connected to the variable displacement hydraulic drive pump
and a high
pressure water pump, the high pressure water pump being in fluid communication
with a
water intake conduit extending from a water supply tank. A discharge conduit
may extend
from an output side of the high pressure water pump to a discharge nozzle, the
discharge
conduit being in fluid communication with the water pressure safety relief
valve. A fixed
displacement charge pump may be engaged with the variable displacement
hydraulic drive
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pump and in fluid communication with the proportional pressure control valve.
The electro-
hydraulic water bypass valve may include: a needle valve having an inlet in
fluid
communication with the discharge conduit, an outlet in fluid communication
with the water
supply tank, and a valve stem; a valve spring configured for urging the valve
stem in a first
direction; and a hydraulic cylinder having a cylinder output shaft configured
for urging the
valve stem in a second direction opposite the first direction, thereby moving
the needle valve
between an open position and a closed position; wherein the proportional
pressure control
valve is in fluid communication with and adapted for controlling the hydraulic
cylinder,
thereby regulating bypass water from the discharge conduit to the water supply
tank in
response to output from the computer. In some embodiments, the needle valve
may be biased
toward the open position by the valve spring. In some embodiments, the valve
spring may be
compressed by a spring plate, the valve stem may include a threaded portion
having a nut
threaded thereon, the nut may be engaged with the spring plate, and the valve
stem may be
slidably disposed through the spring plate.
[00012] In some embodiments, a method of controlling a pressurized water
system may be
provided. The system may have a variable speed water pump in fluid
communication with a
water reservoir and a discharge conduit, a nozzle in fluid communication with
the discharge
conduit, a safety relief valve in fluid communication with the discharge
conduit, the safety
relief valve having a pressure limit and being configured to divert water from
the discharge
conduit to the water reservoir if a pressure in the discharge conduit exceeds
the pressure limit,
a bypass valve in fluid communication with the discharge conduit, a hydraulic
pressure
control valve configured for controlling the bypass valve, a hydraulic
controller configured
for controlling a hydraulic motor, the hydraulic motor being configured for
driving the water
pump, and a computer in communication with the hydraulic controller and the
hydraulic
pressure control valve. The method may include: setting a preselected water
pressure for the
CA 02882163 2015-02-18
system in the computer via an operator interface, the preselected water
pressure being less
than the pressure limit; activating the water pump; sensing a pressure in the
discharge conduit
using a pressure transducer; sending a first signal representative of the
pressure as a first
input to the computer; sensing a speed of the water pump using a speed sensor;
sending a
second signal representative of the speed as a second input to the computer;
and in response
to the first and second signals, sending a first output signal from the
computer to the
hydraulic controller thereby controlling the speed of the water pump within a
range of speeds
and sending a second output signal from the computer to the hydraulic pressure
control valve
thereby controlling the bypass valve in a manner that tends to maintain the
pressure in the
discharge conduit at the preselected water pressure.
[00013] In some embodiments, the water pump may have a minimum speed, and the
method
may further include reducing the speed of the water pump if the pressure in
the discharge
conduit is greater than the preselected water pressure and the speed of the
water pump is
greater than the minimum speed.
[00014] In some embodiments, the method may further include diverting water
from the
discharge conduit through the bypass valve if the pressure in the discharge
conduit is greater
than the preselected water pressure and the speed of the water pump is less
than or equal to
the minimum speed.
BRIEF DESCRIPTION OF THE DRAWINGS
[00015] An example of a system for regulation and control of water pressure
and flow rate in
a high pressure water application is shown in the accompanying drawings in
which:
[00016] Fig. 1 is a schematic diagram of a water control and regulation
system.
[00017] Fig. 2 is a front elevation view in partial cross-section of the EHW
bypass valve of
the system of Fig. 1.
[00018] Fig. 3 is a side elevation view of the EHW bypass valve of the system
of Fig. 1.
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[00019] Fig. 4 is a top front perspective view of the EHW bypass valve of the
system of Fig.
1.
[00020] Fig. 5 is a top back perspective view of the EHW bypass valve of the
system of Fig.
1.
DETAILED DESCRIPTION
[00021] The following terms as used herein should be understood to have the
indicated
meanings unless the context requires otherwise.
[00022] When an item is introduced by "a" or "an," it should be understood to
mean one or
more of that item.
[00023] "Communication" means the transmission of one or more signals from one
point to
another point. Communication between two objects may be direct, or it may be
indirect
through one or more intermediate objects. Communication in and among
computers, 1/0
devices and network devices may be accomplished using a variety of protocols.
Protocols
may include, for example, signaling, error detection and correction, data
formatting and
address mapping. For example, protocols may be provided according to the seven-
layer
Open Systems Interconnection model (OSI model), the TCP/IP model, or any other
suitable
model.
[00024] "Comprises" means includes but is not limited to.
[00025] "Comprising" means including but not limited to.
[00026] "Computer" means any programmable machine capable of executing machine-
readable instructions. A computer may include but is not limited to a general
purpose
computer, mainframe computer, microprocessor, computer server, digital signal
processor,
personal computer (PC), personal digital assistant (PDA), laptop computer,
desktop
computer, notebook computer, smartphone (such as Apple's iPhoneTM, Motorola's
AtrixTM
4G, and Research In Motion's BlackberryTM devices, for example), tablet
computer, netbook
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computer, portable computer, portable media player with network communication
capabilities (such as Microsoft's Zune HDTM and Apple's iPod TouchTm devices,
for
example), camera with network communication capability, wearable computer,
point of sale
device, or a combination thereof. A computer may comprise one or more
processors, which
may comprise part of a single machine or multiple machines.
[00027] "Computer readable medium" means an article of manufacture having a
capacity for
storing one or more computer programs, one or more pieces of data, or a
combination thereof
A computer readable medium may include but is not limited to a computer
memory, hard
disk, memory stick, magnetic tape, floppy disk, optical disk (such as a CD or
DVD), zip
drive, or combination thereof.
[00028] "GUI" means graphical user interface.
[00029] "Having" means including but not limited to.
[00030] "Interface" means a portion of a computer processing system that
serves as a point
of interaction between or among two or more other components. An interface may
be
embodied in hardware, software, firmware, or a combination thereof.
[00031] "I/0 device" may comprise any hardware that can be used to provide
information to
and/or receive information from a computer. Exemplary I/O devices may include
disk drives,
keyboards, video display screens, mouse pointers, joysticks, trackballs,
printers, card readers,
scanners (such as barcode, fingerprint, iris, QR code, and other types of
scanners), RFID
devices, tape drives, touch screens, cameras, movement sensors, network cards,
storage
devices, microphones, audio speakers, styli and transducers, and associated
interfaces and
drivers.
[00032] "Memory" may comprise any computer readable medium in which
information can
be temporarily or permanently stored and retrieved. Examples of memory include
various
types of RAM and ROM, such as SRAM, DRAM, Z-RAM, flash, optical disks,
magnetic
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tape, punch cards, EEPROM, and combinations thereof Memory may be virtualized,
and
may be provided in or across one or more devices and/or geographic locations,
such as RAID
technology, for example.
[00033] "Module" means a portion of a prop-am.
[00034] "Program" may comprise any sequence of instructions, such as an
algorithm, for
example, whether in a form that can be executed by a computer (object code),
in a form that
can be read by humans (source code), or otherwise. A program may comprise or
call one or
more data structures and variables. A program may be embodied in hardware,
software,
firmware, or a combination thereof A program may be created using any suitable
programming language, such as C, C++, Java, Pen, PHP, Ruby, SQL, other
languages, and
combinations thereof Computer software may comprise one or more programs and
related
data. Examples of computer software may include system software (such as
operating system
software, device drivers and utilities), middleware (such as web servers, data
access software
and enterprise messaging software), application software (such as databases,
video games and
media players), firmware (such as software installed on calculators, keyboards
and mobile
phones), and programming tools (such as debuggers, compilers and text
editors).
[00035] "Signal" means a detectable physical phenomenon that is capable of
conveying
information. A signal may include but is not limited to an electrical signal,
an
electromagnetic signal, an optical signal, an acoustic signal, or a
combination thereof
[00036] For exemplary purposes only, an embodiment of the present invention is
described
as associated with a mobile, highway speed, hydroexcavating machine. One such
machine is
the VacAll Industries unit identified as the VacAll AllExcavate TM machine. In
a particular
environment, the excavating system may derive its power from any source
adapted to drive a
hydrostatic drive pump. In some embodiments described herein, the power may be
derived
from a power takeoff connected to the transmission of a truck which transports
the chassis-
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mounted machine.
[00037] Turning to Fig. 1, a schematic of a water pressure and flow control
system 10 is
illustrated. Broadly described, a high pressure water pump 12 may draw water
from a water
supply tank or reservoir 14 and deliver the water via a discharge conduit 16
to a lance or
handgun 21 having a discharge nozzle 18. The operator may control the water
discharge by
activation of a trigger or controller at the lance 21.
[00038] System 10 may have a water pressure safety relief valve 20 in fluid
communication
at an upstream location 15 of the discharge conduit 16 to allow water to flow
back to the
water supply tank 14 in situations where the water pressure in the discharge
conduit 16
exceeds a prescribed, high pressure limit. Without EHW bypass valve 22 as
described below,
if the operator were to reduce the water flow from the nozzle 18 below a
certain threshold, a
back pressure may be created in the output conduit 16 because the speed of the
water pump
12 may not be able to be reduced sufficiently due to pump lubrication
requirements. When
the back pressure exceeds the safety limit set on relief valve 20, the excess
water flow would
be dumped back to the water supply tank 14 via safety relief conduit 19. Thus,
without EHW
bypass valve 22, it would be difficult to control the water discharge flow
over a broad range
of pump speeds.
[00039] In light of that, the system 10, as shown in Fig. 1, may incorporate a
unique EHW
bypass valve 22 disposed at a downstream location 17 of the discharge conduit
16. This
bypass valve 22 may open and close in response to water pressure sensed in
discharge
conduit 16 and the speed of the high pressure water pump 12. As described
further below,
this bypass valve 22 may allow the operator to reduce the flow rate from the
nozzle 18 over a
broad range of pump speeds.
[00040] As shown in Fig. 1, an operator interface device 24 may allow the
operator to enter a
prescribed or preselected water discharge pressure setting. A microprocessor
or other
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suitable computer 26, well known and understood in the art, may receive input
from a water
pump speed sensor 28 operatively disposed at the pump input shaft 30.
Interface device 24
may be part of or separate from computer 26. The computer 26 may also receive
data from a
water pressure transducer 32 operatively disposed in fluid communication with
an upstream
location 15 of discharge conduit 16. The computer 26 may utilize the data
received from
both sensor 28 and transducer 32 to control and regulate a variable
displacement pump 34
and a proportional pressure control valve 36 which operatively controls the
EHW bypass
valve 22, as will be described further below. Thus, by utilizing data from the
sensor 28 and
transducer 32, the speed of the water pump 12 may be varied and water pressure
in the
discharge conduit 16 (and, ultimately the nozzle 18) may be controlled via the
EHW bypass
valve 22, thereby controlling and regulating the water flow rate over a wide
range of values.
[00041] As will be appreciated by persons of ordinary skill in the art,
computer 26 may have
one or more memories programmed with one or more programs on one or more
computer
readable media configured for carrying out the control processes described
herein. Computer
26 may also have one or more I/O devices (such as interface device 24) and one
or more
GUI's or other user interfaces configured for allowing a user to operate
computer 26 as
described herein. Although only one computer 26 is shown, two or more such
computers
may be employed, depending on the needs of the particular application.
[00042] Operation of the present system 10 may be achieved when, based on the
required
water flow, the operator installs a nozzle 18 into a water handgun or lance
21, selects the
pressure required at the operator interface 24 for the specific application,
and activates the
high pressure water pump 12. A signal is sent to a hydraulic controller 35
which controls
variable displacement hydraulic pump 34 (driven by the power take off 13 on
the truck). The
hydraulic pump 34 may power a hydraulic motor 40 with an output shaft 30 which
in turn
drives the high pressure water pump 12.
11
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[00043] It should be understood that various hydraulic reservoirs 99 may be
used to supply
the system with hydraulic fluid. The water pump 12 may be driven to the
required speed for
the desired operation. The speed range of water pump 12 may vary depending on
operating
conditions. The computer 26 may receive pump speed data from sensor 28 and
water
pressure data from pressure transducer 32 and may adjust the water pump speed
to ensure the
most efficient operation for the selected pressure. If the speed for the
output flow rate
(controlled by the operator at the lance or handgun 21) is within the
operating parameter of
the water pump 12 (as dictated by the pump lubrication system), and the
pressure is at the
operator's preselected setting, then no further action may be required.
[00044] If, however, the pressure noted at the transducer 32 is higher than
the preselected
pressure and less than the safety relief set point limit of relief valve 20,
the computer 26 may
adjust the displacement of the variable displacement hydraulic drive pump 34
via the
hydraulic controller 35 to reduce the speed of the motor 40 and high pressure
water pump 12
to a minimum speed recommended by the water pump manufacturer. After the water
pump
12 reaches the minimum allowable speed and the preselected pressure (via
interface device
24) is not achieved, the EHW bypass valve 22 may activate and divert excess
water back to
the water supply tank 14. Once the preselected pressure is reached, the EHW
bypass valve
22 may maintain this pressure and water flow rate until the condition is no
longer valid. As
the operator increases or decreases the discharge of water through the nozzle
18, as
conditions change, based on data from the pressure transducer 32 and speed
sensor 28, the
computer 26 may send a signal to the EHW bypass valve 22 to increase or
decrease the
bypass water flow, as needed, in order to maintain the desired pressure and
flow rate in line
16.
[00045] The operation of the EHW bypass valve 22 may be controlled by a
proportional
pressure control valve 36. Hydraulic pressure may be supplied to the
proportional control
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valve 36 from the control pressure circuit 41 of the hydraulic drive pump 34.
The control
circuit 41 for the hydraulic drive pump 35 may be supplied by a charge pump 42
that is
integral to the hydraulic drive pump 34, as shown in Fig. 1. Alternatively,
charge pump 42
may be separate from drive pump 34.
000461 Figs. 2-5 illustrate an exemplary structural configuration of the EHW
bypass valve
22. The valve 22 may include a ball tip stem needle valve 60 or other suitable
valve that is
biased toward an open position by a spring 52 and forced closed by a hydraulic
cylinder 54.
The pressure to cylinder 54 may be supplied via an input line 53 by the charge
pump 42 and
controlled by an electro-proportional valve 36 which receives a control signal
from output 80
of computer 26. As would be understood by one skilled in the art, hydraulic
cylinder 54 may
urge valve stem 56 downwardly against the opposing compression force of the
spring 52. As
the stem 56 moves upwardly or downwardly, needle valve 60 may open and close
thereby
controlling water flow from the water inlet side 62 to the water outlet side
64 of valve 60.
The water passing through valve 60 may be dumped back to the water supply tank
14 as
described above.
[00047] Figs. 2 and 3 further illustrate an exemplary construction of EHW
bypass valve 22.
Hydraulic cylinder 54 may be mounted on a plate 63 with an inlet hydraulic
tube 53
connected to the cylinder 54 by an adapter 55. A pair of hex nut and jam nut
70 may be
attached to the cylinder output shaft 69 to interact with (e.g., bear downward
on) a similar
hex nut and jam nut pair 71, which may be attached to a threaded portion of
valve stem 56 in
order to capture the spring plate 72. The valve stem 56 may slidingly pass
through the spring
plate 72, with spring 52 urging the spring plate 72 upwardly by compressive
forces. The
movement of spring plate 72 may result in the movement of the valve stem 56
within the
needle valve 60. Needle valve 60 may be mounted to the EHW bypass valve 22 on
a water
valve mounting plate 61. When the hydraulic cylinder 54 urges shaft 69
downwardly, the
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spring plate 72 may move downwardly, compressing the spring 52, and the valve
60 may be
closed. Thus, in response to the control signals from computer 26, valve 60
may be placed in
any desired state, from fully closed, to partially open, to fully open,
depending on how much
excess water needs to be diverted to the tank 14 in order to maintain the
desired flow rate and
pressure at nozzle 18.
[00048] As noted above, hydraulic cylinder 54 may be operated by proportional
control
valve 36. Hydraulic fluid pressure may be supplied to a manifold 37 (see Fig.
5) of the
control valve 36 from the control pressure circuit 41 from a charge pump 42
(see Fig. 1) of
the hydraulic pump 34. The proportional control valve 36 may receive an output
signal 80
from the computer 26 in response to data received from the pressure transducer
32 in the
discharge conduit 16. Fig. 3 shows a side elevation view of the EHW bypass
valve 22 with
the manifold 37 and the proportional control valve 36 mounted on hydraulic
mounting plate
63. Mounting plate 63 may be held in a rigid, space-apart relationship with
needle valve
mounting plate 61 by spacer tubes 65. Needle valve 60 may be mounted on
mounting plate
61.
[00049] The EHW bypass valve 22 of the present system may allow the operator
to regulate
water flow through nozzle 18 from 25 gpm to 0 gpm, for example, at a preset
pressure with a
single (one size) water pump 12.
As noted above, in previous systems, the
maximum/minimum flows were completely dependent on the size of the water pump
mounted on the chassis of the truck or trailer. For example, a 25 gpm-sized
high pressure
water pump, due to minimum speed requirements set by the manufacturer because
of pump
lubrication limits, may have a minimum flow rate of approximately 10 gpm. To
obtain flow
rates below 10 gpm, such as down to the 3-5 gpm range, for example, a smaller
sized pump,
perhaps a 10 gpm pump, would be required. Thus, a 25 gpm sized pump included
in an
embodiment of the present inventive system can do the job of several machines
based on
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jobsite requirements. For example, when using a hydroexcavator system around
fiber optics,
the water flow and pressure is often dictated by the municipality or
telecommunications
provider. With a hydroexcavator equipped with an embodiment of the present EHW
bypass
valve 22, there are fewer limitations preventing the machine from adapting to
the particular
jobsite conditions.
[00050] The embodiments described herein are some examples of the current
invention.
Various modifications and changes of the current invention will be apparent to
persons of
ordinary skill in the art. Among other things, any feature described for one
embodiment may
be used in any other embodiment. The scope of the claims should not be limited
by the
preferred embodiments set forth in the Description, but should be given the
broadest
interpretation consistent with the Description as a whole.
