Note: Descriptions are shown in the official language in which they were submitted.
CA 02520345 2005-09-21
APPARATUS, SYSTEM, AND MEANS FOR
A MODULAR BACKPRESSURE SENSOR
BACKGROUND OF THE INVENTION
HELD OF THE INVENTION
[0001] This invention relates to a removable pressure calibration
module
installed in a pressure sensitive fluid delivery nozzle. One embodiment
relates to a
system for fueling large vehicles.
DESCRIPTION OF THE RELATED ART
[0002] Large construction and mining vehicles are often equipped with a
fueling system that allows the fuel tank to be filled from the bottom. This
enables the
fueling of the vehicle to take place from ground level as many of the vehicles
of this
type are extremely large. There are two types of fueling systems that allow
fueling from
the bottom of the tank. They both incorporate three common components: 1) a
fueling
nozzle that senses a pressure change in order to shut off, 2) a fueling
receiver that is
permanently attached to the fuel tank to which the nozzle attaches, and 3) a
fuel vent
that can sense when the fuel tank is filled and provide a pressure change that
can be
sensed by the nozzle. One system uses a vent that closes an exhaust port when
the fuel
tank is full allowing the tank itself to become pressurized by the incoming
fuel. The fuel
nozzle senses this pressure and shuts off at a pre-determined pressure level.
The second
type of system uses a vent that is attached by one or more hoses to the fuel
receiver.
When the tank is full, the vent provides a pressure change to one or more of
the hoses
which causes a valve in the fuel receiver to change position which in turn
causes the fuel
nozzle to shut off. In some systems, the same fuel nozzle can be used in
conjunction
with different combinations of vents and receivers to provide either a
pressure operated
system (tank is pressurized) or a non-pressurized system (the tank is not
pressurized).
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[0003] Most fuel nozzles of this type incorporate a pressure sensing
device.
Most fuel nozzles, in current use, incorporate either a spring biased piston
or diaphragm
to sense the change in back pressure of the fuel flowing through the nozzle.
The change
in back pressure causes the nozzle to shut off when the pressure reaches a pre-
set
pressure. The pressure is typically calibrated and pre-set by mounting the
entire nozzle
on specialized equipment in a repair shop. Moreover, the nature of its
function subjects
the pressure sensing component to a significantly greater rate of wear than
the other
parts of the nozzle.
[0004] Due to the extreme conditions of use, the nozzles typically require
frequent rebuilding¨often after every few months or even after every few weeks
of
operation. The entire nozzle must be returned to a rebuild center to be
completely
disassembled, reassembled with certain potentially new components, and tested
as a unit
on a fairly complex test stand. Only a few fully equipped rebuild sites exist.
This
requires that complete back up sets of these expensive nozzles be kept on hand
at the
mining and construction sites for use while a first set of nozzles is being
rebuilt.
[0005] Additionally, some fueling systems physically restrict the
diameter of
the delivery end of the fueling nozzle. At one time, most nozzles incorporated
a rubber
bumper on the end of the fuel nozzle to provide physical protection from
incidental
damage when the nozzle was not in use. Because of the new diameter
restrictions, many
users remove the rubber bumpers in order to fit on the newer fuel receivers,
thus
removing an important damage prevention feature of the nozzles.
[0006] From the foregoing discussion, it should be apparent that a need exists
for an apparatus, system, and method that allows the pressure sensing
component to be
removed and replaced modularly on site. Beneficially, such an apparatus,
system, and
method would also allow the end user to repair, set, and calibrate the module,
obviating
the need for use of a rebuild center. A need also exists for a related
apparatus, system,
and method to protect the end of the nozzle when the nozzle is not in use.
Beneficially,
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such an apparatus, system, and method, would be adaptable to various diameter
restrictions of the fuel receiver.
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4%
SUMMARY OF THE INVENTION
[0007] The present invention has been developed in response to the present
state of the art, and in particular, in response to the problems and needs in
the art that
have not yet been fully solved by currently available fuel nozzles.
Accordingly, the
present invention has been developed to provide an apparatus, system, and
method for a
pressure sensing component that can be removed and repaired on site, and that
thus
overcomes many or all of the above-discussed shortcomings in the art.
[0008] This allows an end user, for example a mine site, to quickly rebuild
worn nozzles without sending the entire unit to a dedicated rebuild center.
This not only
saves direct costs associated with shipping and handling but also provides an
increased
safety margin in that a fuel soaked nozzle is not shipped to another facility.
End users
see a significant savings in rebuild costs by rebuilding the nozzles so
quickly within
their own facilities and without the need for specialized tools or calibration
devices.
[0009] The modular backpressure sensor essentially comprises a pressure
sensing chamber defined by a modular housing. The pressure sensing chamber is
configured to communicate with the fluid flow channel of the fluid delivery
nozzle and
is equipped with a pressure sensing device or material. The pressure response
member
responds to pressure within the fluid flow channel of the nozzle by activating
the shut-
off valve within the fluid delivery nozzle. A biasing member reacts to
pressure on the
pressure response member. A retainer retains either or both of the biasing
member and
the pressure response member within the modular housing.
[0010] The modular backpressure sensor is configured to removably engage a
fluid delivery nozzle having a body with an outlet configured to engage a
fluid storage
tank connector and an inlet configured to engage a fluid delivery hose. A flow
channel
within the fluid delivery nozzle permits fluid flow from the inlet to the
outlet and is
configured to accommodate a shut-off valve. The shut-off valve is configured
to
cooperate with a stopper configured to block the flow of fluid through the
valve. The
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,
fluid delivery nozzle comprises an interface configured to engage the modular
backpressure sensor and to communicate backpressure to the modular
backpressure
sensor.
[0011] Together the modular backpressure sensor and associated fluid
delivery nozzle comprise a system for delivering fluid to a receptacle. The
fluid
delivery nozzle is configured to removably engage the modular backpressure
sensor.
The fluid delivery nozzle body has an outlet configured to engage a fluid
receiving tank
connection and an inlet configured to engage a fluid conductor such as a hose.
A flow
channel in the fluid delivery nozzle body permits fluid flow from the inlet to
the outlet.
The flow channel includes a shut-off valve configured to block the flow of
fluid through
the flow channel. The fluid delivery system also includes a fluid receiving
tank
connection which may engage the fluid outlet of the fluid delivery nozzle and
a fluid
conductor with a nozzle connection which may engage the fluid inlet of the
fluid
delivery nozzle.
[0012] The present
invention also includes a modular backpressure sensor kit
for maintaining a fluid delivery nozzle having a modular backpressure sensor.
The kit
may include at least one modular backpressure sensor calibrated to operate in
cooperation with the fluid delivery nozzle and optionally may include other
maintenance
and repair elements such as tools, replacement sealing rings, replacement
bushings, and
replacement snap rings.
[0013] A means for a sensing fluid backpressure from a fluid receptacle is
disclosed. The means comprises modular means for sensing fluid backpressure,
means
for removably connecting the modular means for sensing fluid backpressure to a
fluid
delivery nozzle, means for communicating fluid back pressure within a fluid
flow
channel of the fluid delivery nozzle to the modular means for sensing fluid
backpressure, means for generating a backpressure response within the modular
means
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for sensing fluid backpressure and means for communicating the generated
backpressure
response to a shut-off valve within the fluid flow channel.
[0014] Reference throughout this specification to features, advantages, or
similar language does not imply that all of the features and advantages that
may be
realized with the present invention should be or are in any single embodiment
of the
invention. Rather, language referring to the features and advantages is
understood to
mean that a specific feature, advantage, or characteristic described in
connection with an
embodiment is included in at least one embodiment of the present invention.
Thus,
discussion of the features and advantages, and similar language, throughout
this
specification may, but do not necessarily, refer to the same embodiment.
[0015] Furthermore,
the described features, advantages, and characteristics of
the invention may be combined in any suitable manner in one or more
embodiments.
One skilled in the relevant art will recognize that the invention may be
practiced without
one or more of the specific features or advantages of a particular embodiment.
In other
instances, additional features and advantages may be recognized in certain
embodiments
that may not be present in all embodiments of the invention.
[0016] These features and advantages of the present invention will become
more fully apparent from the following description and appended claims, or may
be
learned by the practice of the invention as set forth hereinafter.
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,
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order that the advantages of the invention will be readily
understood, a more particular description of the invention briefly described
above will
be rendered by reference to specific embodiments that are illustrated in the
appended
drawings. Understanding that these drawings depict only typical embodiments of
the
invention and are not therefore to be considered to be limiting of its scope,
the invention
will be described and explained with additional specificity and detail through
the use of
the accompanying drawings, in which:
[0018] Figure 1 is a cross-section diagram illustrating a lateral
section of one
embodiment of an assembled modular backpressure sensor;
[0019] Figure 2 is an exploded view of one embodiment of a modular
backpressure sensor;
[0020] Figure 3 is a perspective cross-section diagram illustrating a
fluid
delivery nozzle with a modular backpressure sensor installed in accordance
with one
embodiment of the present invention;
[0021] Figure 4 is a schematic cross-section diagram illustrating a
fluid
delivery nozzle with a modular backpressure sensor installed in accordance
with one
embodiment of the present invention;
[0022] Figure 5 is a schematic block diagram illustrating one embodiment
of
a system for fluid delivery using a modular backpressure sensor; and
[0023] Figure 6 is a schematic block diagram illustrating one embodiment
of
a modular backpressure sensor kit.
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. ,
DETAILED DESCRIPTION OF THE INVENTION
[0024] Many of the functional units described in this specification have
been
labeled as modules, in order to more particularly emphasize their
implementation
independence.
[0025] Furthermore, the described features, structures, or
characteristics of
the invention may be combined in any suitable manner in one or more
embodiments. In
the following description, numerous specific details are provided to
facilitate a thorough
understanding of embodiments of the invention. One skilled in the relevant art
will
recognize, however, that the invention may be practiced without one or more of
the
specific details, or with other methods, components, materials, and so forth.
In other
instances, well-known structures, materials, or operations are not shown or
described in
detail to avoid obscuring aspects of the invention.
[0026] Figure 1 is a cross-section diagram of one embodiment of an
assembled modular backpressure sensor 100. As depicted, the modular
backpressure
sensor 100 comprises a modular housing 102, a backpressure piston 104, a
piston spring
106, a piston spring retainer 108, a housing head 110, a fluid pressure
chamber 112, a
piston rod 114, a longitudinal bore 116, a forward radial bore 118, a fluid
pressure
chamber radial bore 120, a backpressure piston extension 122, a lateral groove
124, a
housing head aperture 126, and a bushing 128.
[0027] The modular housing 102 contains the backpressure piston 104 and
the piston spring 106. The backpressure piston 104 forms a fluid impermeable
seal with
the walls of the modular housing 102. The piston spring retainer 108 confines
the piston
spring 106 within the modular housing 102. The housing head 110 seals the
forward
end of the modular housing 102 and cooperates with a wall of the modular
housing 102
and the piston 104 to define the fluid pressure chamber 112 between the
backpressure
piston 104 and the housing head 110. As depicted, the modular housing 102 has
a
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CA 02520345 2005-09-21
circular cross-section. In alternative embodiments, the modular housing 102
may have
an elliptical or other non-circular cross-section.
[0028] In the
illustrated embodiment the piston rod 114 passes through the
cylinder head aperture 126 and connects to the backpressure piston 104. The
bushing
128 aligns the piston rod 114 with a longitudinal axis 115 of the modular
housing 102.
Fluid enters the piston rod 114 through the forward radial bore 118 and flows
through
the longitudinal bore 116 and enters the fluid pressure chamber 112 through
the fluid
pressure chamber radial bore 120. The flowing fluid fills the fluid pressure
chamber
112 and the pressure moving the fluid begins to build in the fluid pressure
chamber.
Alternatively, a flexible diaphragm in the housing head 110 may transfer
pressure from
a fluid in the piston rod 114 to a fluid such as a gas within the fluid
pressure chamber
112. In yet another embodiment, the pressure of the fluid in the piston rod
114 is
registered by an electronic pressure sensor in communication with the fluid
flowing in
the piston rod 114.
[0029] Increasing pressure within the fluid pressure chamber 112 drives the
backpressure piston 104 back against the resistance of the piston spring 106.
In a further
embodiment, a compressible solid, gas, liquid, or other resilient material may
be used in
place of the piston spring 106 to provide resistance.
[0030] The movement of the backpressure piston 104 retracts the piston rod
114 in direction 130. The piston extension 122, with its lateral groove 124
serves as an
attachment site for an activation handle (See Fig. 3).
[0031] Figure 2 is an exploded view of the modular backpressure sensor 100
illustrated in Figure 1. As depicted, in addition to the parts identified in
Figure 1, the
modular backpressure sensor 100 comprises snap rings 202 and 204, 0-ring
channels
206, 0-rings 208, bushing snap ring 210, and backpressure piston seal 212.
[0032] In the depicted embodiment snap ring 202 engages an interior channel
in the modular housing 102 and secures the piston spring retainer 108. Snap
ring 204
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engages an interior channel in the modular housing 102 and secures the housing
head
110. The snap rings 202,204 prevent internal components within the housing 102
from
escaping in response to the forces imposed by the spring 106 and fluid force
within the
fluid pressure chamber 112. The 0-ring channels 206 receive and retain the 0-
rings
208. The 0-rings 208 retain the modular housing 102 within an opening within a
fluid
nozzle. The bushing snap ring 210 engages a channel 127 in the bushing 128.
The
bushing snap ring 210 secures the bushing 128 to the housing head 110. The
backpressure piston 104 incorporates an annular channel to accept a
backpressure piston
seal 212 that forms a fluid impermeable seal with the interior wall of the
modular
housing 102 such that fluid is retained within the fluid pressure chamber 112.
[0033] In an alternative embodiment, the housing head 110 may be formed as
an integral part of the modular housing 102. Additionally, the housing head
110 may be
formed as a cap that attaches to the modular housing body by means of threads,
grooves,
flanges, clips, or other fastening means. In another embodiment, the piston
spring
retainer 108 may be formed as an integral part of the modular housing 110. The
piston
spring 106 may be removed from the modular housing 110 through an opening
configured to accommodate a removable housing head 110. The piston spring
retainer
108 may also be formed as a cap that attaches to the modular housing body by
means of
threads, grooves, flanges, clips, or other fastening means. In embodiments
with an
integrated housing head 110 or piston spring retainer 108, snap rings 202 or
204 may not
be required.
[0034] Figure 3 is a cross-section diagram illustrating one embodiment of a
combined fluid delivery apparatus 300 comprising a fluid delivery nozzle 301
configured to receive a modular backpressure sensor 100. As depicted, the
combined
apparatus 300 comprises a modular backpressure sensor 100, an actuator handle
302, a
nozzle body 304, a removable back plate 306, a piston rod 114, a sealing
poppet 308, a
fluid intake port 310, a fluid flow channel 312, a fluid outlet port 314, a
pull-back
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,
handle 318, a carry handle 320, a fluid shut-off valve 322 and a nozzle
pressure cavity
324.
[0035] In operation, the fluid intake port 310 connects to a fluid
conductor
hose. The pull back handle 318 cocks the fluid outlet port 314 for connection
to a
receptacle connector. The carry handle 320 facilitates transport of the nozzle
301.
[0036] The activator handle 302 cooperates with the modular backpressure
sensor 100 to extend the piston rod 114, pushing the sealing poppet 308
forward to open
the fluid shut-off valve 322. The removable back plate 306 detaches to allow
withdrawal of the modular backpressure sensor 100 from the nozzle pressure
cavity 324.
[0037] The back plate 306 may be removed with standard tools, permitting
access to the modular backpressure sensor 100. Preferably, the back plate 306
is
secured to the nozzle 301 by way of common fasteners such as screws, nuts,
thumb-
screws, thumb-nuts, or the like.
[0038] The sealing poppet 308 may also be removed using standard tools
such as needle nose pliers, a screw driver, or, alternatively, a poppet
spanner wrench.
When the back plate 306 and poppet 308 have been removed, the modular
backpressure
sensor 100 can be withdrawn from the rear of the nozzle body 301. The modular
housing 102, the housing head 110, and the piston spring retainer 108 are
preferably
made of rigid, fluid insoluble, materials of sufficient size and thickness to
withstand the
pressure exerted by the piston spring 106 and by fluid within the pressure
sensing
chamber 112. In one embodiment, the modular housing 102, the housing head 110,
and
the piston spring retainer 108 are made of hard plastic, aluminum, stainless
steel, or the
like.
[0039] The robust nature of the modular housing 102, the housing head
110
and the piston spring retainer 108 facilitate the modular nature of the
modular
backpressure sensor 100. Moreover, the modular backpressure sensor 100 can be
safely
and conveniently removed and replaced. In standard existing fluid delivery
nozzles, the
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= ,
piston spring sits directly within the nozzle backpressure chamber and is
retained by a
back plate. However, the back plate must be removed using specialized tools.
Due to
the bias forces within the spring of conventional fluid delivery nozzles,
removal of the
back plate without the special tools can cause the piston spring to violently
ejects from
the nozzle body creating a risk of potentially serious injury, especially to
the eyes and
face of a user.
[0040] Alternatively, the fluid delivery nozzle 301 may lack a nozzle pressure
cavity 324 and the modular backpressure sensor 100 may engage the fluid
delivery
nozzle 301 directly, with the modular housing 102 exposed. Additionally, the
modular
backpressure sensor 100 may be connected to substantially any external surface
of the
fluid delivery nozzle 301.
[0041] In a further embodiment the modular backpressure sensor 100 may
incorporate electronic, digital, or analog elements to supplement or replace
the
mechanical elements. In such an embodiment the modular backpressure sensor 100
may
interact with the fluid delivery nozzle 301 through a sensing and
communication
element and may directly connect to the fluid delivery nozzle 301 or reside in
a remote
location. Such an embodiment would include a power source, an electronic
modular
backpressure sensor, and a shut-off switch. The shut-off switch may be
configured to
trigger an electronic or mechanical shut-off mechanism within the fluid
delivery nozzle.
[0042] Figure 4 is a cross-section diagram illustrating a lateral
section of one
embodiment of a combined fluid delivery apparatus 300. As depicted, the
combined
apparatus 300 comprises a fluid delivery nozzle 301, a modular backpressure
sensor
100, a cam 402, a piston pin 404, a cam cavity 406, a valve spring 408, a pull-
back
spring 410, a release dog 412, a sleeve spring 414, a pull-back sleeve 416, a
dog ring
418, an axle 422, a nub 426, and a tooth 428.
[0043] The pull-back handle 318 cocks the nozzle 301 for attachment to a
receptacle connector (not shown). Cocking the nozzle 301 prepares the nozzle
301 for
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CA 02520345 2005-09-21
engaging the receptacle connector. Pulling back on the pull-back handle 318
moves the
attached pullback sleeve 416 toward the rear of the nozzle 301. Backward
movement of
the pullback sleeve 416 releases the release dogs 412 that extend around the
inner
circumference of the fluid outlet port 314 of the nozzle body. A nub 426 on
the inside
wall of the pullback sleeve 416 slides along a release dog 412 and forces the
release dog
412 to pivot and extend a tooth 428 of the release dog 412. The release dogs
412 open
to increase the effective diameter between release dogs 412. The pull-back
motion of
the pullback sleeve 416 biases the sleeve spring 414 which facilitates return
of the pull-
back sleeve 416.
[0044] Once, the
nozzle 301 is inserted into a receptacle connector, the pull-
back handle 318 is moved forward with assistance from the pull-back spring
410. The
nub 428 forces the release dogs 412 to close causing the release dogs 412 to
clamp
down on the receptacle connector and engage the receptacle connector. The dog
ring
418 locates the release dogs 412 in either an open when the pull-back handle
318 is
moved backward and in a closed position when the pull-back handle 318 is moved
forward. Cocking the pull-back handle 318 locks the release dogs 412 in open
position,
allowing the nozzle 300 to be attached to or removed from a receptacle
connector.
[0045] The activator handle 302 turns on axle 422 which in turn actuates cam
402 within cam chamber 406, exerting pressure on the piston pin 404 and on the
backpressure piston extension 122. Moving the activator handle 302 to pivot in
a
counter-clockwise direction about the cam 402 allows the piston spring 106 to
move the
backpressure piston extension 122, the backpressure piston 104, the piston rod
114 and
associated poppet 308 forward, opening the fluid shut-off valve 322. The fluid
shut-off
valve 322 is pressed against the valve spring 408 into a retracted position by
the
receptacle connector to which the nozzle 301 is attached for operation.
Therefore,
removal of the receptacle connector closes the valve spring 408.
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CA 02520345 2005-09-21
[0046] Downward pressure on the activator handle 302 retracts the piston
extension 122 and its associated structures including the poppet 308. This
allows the
poppet 308 to seal against the fluid shut-off valve 322 which in turn stops
fluid flow
through the nozzle. Such downward pressure causes the activator handle 302 to
pivot in
a counter-clockwise direction about the cam 402 and retracts the piston
extension 122
and the poppet 308 to close the fluid shut-off valve 322.
[0047] Downward pressure on the activator handle 302 retracts the piston
extension 122 and its associated structures including the poppet 308. Figure 4
also
illustrates the cross-section shape of the piston pin 404. In particular the
piston pin 404
includes two opposing flattened edges 430. These edges 430, together with
linkage 432
translate the rotational movement of the handle 302 about the cam 402 into
lateral
movement to move the poppet 308.
[0048] Figure 5 is a schematic block diagram illustrating one embodiment
of
a system 500 for fluid delivery using a modular backpressure sensor. As
depicted, the
system 500 comprises a fluid source 502, a fluid conductor 504, a nozzle
connection
506, a fluid delivery nozzle 301, a modular backpressure sensor 100, a
receiver
connection 508, a fluid receiver 510, and a replacement modular backpressure
sensor
512.
[0049] The fluid source 502 may be a fuel, oil, water, or other fluid
storage
tank. In addition, the fluid in the fluid source 502 may comprise a material
in a liquid,
gas, or semi-solid state. The fluid conductor 504 transfers the fluid from the
fluid
source 502 to the nozzle connection 506. The fluid conductor 504 may be a
hose,
conduit, pipe, or other conducting apparatus.
[0050] The fluid delivery nozzle 301 and associated modular backpressure
sensor 100 (discussed above) are removably connected or coupled to the fluid
conductor
504 by way of the nozzle connection 506. The nozzle connection 506 may be
fixed to
the fluid conductor 504.
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=
[0051] The receiver connection 508 may be fixed or removably connected to
the fluid receiver 510. The fluid delivery nozzle 301 starts and stops fluid
delivery to
the fluid receiver 510. The modular backpressure sensor 100 cooperates with
the fluid
delivery nozzle 301 to automatically shut-off fluid flow in response to
detected back
pressure in the fluid delivery nozzle 301. Consequently, the modular
backpressure
sensor 100 is in fluid communication with the fluid flow path 514 such that
the
backpressure is detectable. Preferably, the modular backpressure sensor 100 is
removably connectable to the fluid flow path 514. In certain embodiments, the
modular
backpressure sensor 100 is in mechanical communication with the fluid delivery
nozzle
301 in order to activate a mechanical shut-off valve 322. Alternatively, the
modular
backpressure sensor 100 may send an electrical signal that activates an
electronic shut-
off valve in the fluid delivery nozzle 301.
[0052] Advantageously, the modular backpressure sensor 100 can be
readily
removed using common tools including a Phillips screw driver, a crescent
wrench, or
the like. Consequently, when an operator determines that the modular
backpressure
sensor 100 should be rebuilt due to wear of the spring 106, a certain number
of uses, or
passage of a certain amount of time, the modular backpressure sensor 100 can
be readily
replaced by the replacement modular backpressure sensor 512. Alternatively,
the
modular backpressure sensor 100 may be removed, rebuilt on site, and
reinstalled. On
site rebuilding of the modular backpressure sensor 100 may be accomplished
using
additional tools such as snap-ring pliers, needle nose pliers.
[0053] The piston spring 106, 0-rings 208, and the piston ring 212
comprise
the principle points of wear on the modular backpressure sensor. Pre-
calibrated springs
are available for various levels of shut-off pressure. Therefore, rebuilding
of the
depicted embodiment of the modular backpressure sensor 100 would usually
comprise
removal of the snap ring 202, the piston spring retainer 208, and the piston
spring 106,
and replacement of the piston spring 106 with a new, pre-calibrated spring
106. New
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snap rings 202, 204 may be installed. The snap rings 202, 204 may serve as a
replacement fastener. Additionally, the piston 104 may be removed for seating
of a new
sealing ring within the piston channel 212 and the external modular housing 0-
rings 208
may be replaced.
[0054] The piston spring retainer 108 and snap ring 202 would then be
reinserted into the modular housing 110 and the modular backpressure sensor
100
reengaged with the nozzle body 301. The poppet 308 would be reinstalled on the
piston
rod 114, the activation handle 302 reengaged with the piston extension 122 by
means of
the piston pin 404 and the back plate 306 reattached.
[0055] Figure 6 is a block diagram illustrating one embodiment of modular
backpressure sensor kit 600. A typical kit 600 could include a pre-calibrated
modular
backpressure sensor unit 100 and associated seals 208 required for
installation of the
modular backpressure unit. The associated seals 208 may comprise rubber or
plastic 0-
rings or may comprise the piston seal 212. In another embodiment, the kit 600
may
include several pre-calibrated modular backpressure sensor units 100 each
calibrated for
different backpressure levels.
[0056] The scope of
the claims should not be limited to the preferred em-
bodiments set forth above, but should be given the broadest interpretation
consistent
with the description as a whole.
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