Note: Descriptions are shown in the official language in which they were submitted.
2082683
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PRESSURE EOUALIZING SYSTEM AND VALVE
Field of the Invention
The present invention relates to the containment and
measurement of fluid pressures within a closed loop system. More
particularly, the invention provides a liquid/pressure system
utilizing a novel safety differential valve in connection with
cryogenic liquid tanks, fuel tanks, air conditioning systems for
buildings and flow systems which operate under elevated
pressures.
Background of the Invention
The prior art discloses patents for valves of the packed
spool, lap spool or proportional flow version and valves which
employ cartridge units that may be assembled outside of the valve
body and moved into the bore in the body of the unit, for
example, U.S. Patent No. 4,096,880 to Lemon et al and U.S. Patent
No. 4,220,174. Such prior art constructions do not provide a
valve which can be used in connection with various activating
means such as solenoids, levers, pedals and the like.
U.S. Patent No. 4,877,057 to Chirstensen discloses a
pressure equalizing valve with a spool disposed in a valve body
to regulate fluid communication from an inlet port to outlet
ports in response to a pressure differential between first and
second port disposed on first and second end faces of the valve
body. ~owever, the valve does not provide a means for
differentiating pressures.
Prior to the present invention cryogenic tanks were commonly
equipped with a differential pressure gauge so that an operator
could gauge the amount of liquid in the tank. One side of the
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gauge was connected to the top of the tank and the other side of
the gauge was connected to the bottom. The amount of liquid in
the tank was then determined by inference by the difference of
gauge pressure. In the system, the gauge was protected by an
equalizer valve which was connected to two lines which ran on
both sides of the gauge.
In operation, the operator must open the equalizer valve to
allow the gauge to come to an equilibrium on both sides of the
gauge. After the equalizer is opened, the blocking valves may
be closed. This will permit the gauge to be calibrated or
removed from the system. To reverse the operation and place the
gauge in service requires the blocking valves to be opened and
then the equalizer valve to be closed. If this is not performed
in proper sequence in either operation, an inadvertent high
pressure may occur on one side of the gauge and inactivate the
gauge.
It should be understood that the term "liquid" as used
herein can also refer to a gas which is the result of the liquid
being heated to ambient temperature as is the case with cryogenic
fluids.
Summary of the Invention
According to the present invention there is provided a
closed loop system for measuring an amount of liquid under
pressure in a container. The system comprises a container
holding a liquid under pressure, a novel differential valve
connected by a line to the liquid holding portion of the
container and a line to the gas holding portion of the container,
a differential gauge associated with said differential valve, and
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a means for activating the differential valve.
The differential valve used in the invention is capable of
providing a zero differential pressure. The differential valve
comprises a primary valve body closed at one end and open at the
other end. The valve body has an inlet port for a gas, an inlet
port for a liquid, and an outlet port for the gas and an outlet
port for the liquid (gas) at diametrically opposed positions
relative to inlet ports.
A valve plunger or spool is mounted for longitudinal
movement within a bore in the primary valve body. The plunger
has a pair of reduced diameter portions and ramps forming valving
surfaces. A circumferential notch is formed at each end of the
plunger and a intermediate circumferential notch spaced between
said reduced portions.
O-rings are mounted in each of said notches. The O-rings
at each end cooperate with the inside of the valve body to
prevent escape of gas from inside of the valve body. The O-ring
in the intermediate notch cooperates with the valve body to
separate pressures which come through the inlet ports. There is
provided check valves which are associated with each inlet.
The check valves comprise a valve body having a bore, and
stop means at upper and lower ends of the bore. A plunger is
provided within each of said check valve bores. Each plunger is
associated with the ramp on the primary valve plunger. An O-ring
is placed on the check valve plunger for forming a seal with the
stop means at the upper end of the bore. A spring means is
provided for normally urging the check valve plunger forward in
contact with the ramp.
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The means for activating the plunger of the primary valve
to change direction and move longitudinally within the bore may
be a manual means, a solenoid or a pneumatic device. That is,
any device which can provide linear motion to the plunger to
achieve zero differential can be used so as to have a fully
automated system.
In accordance with an embodiment of the invention a remote
operated closed loop system is provided wherein there is included
an electronic multi-valved means. The electronic multi-valved
means has a solenoid which is connected to a computer, and a
normally closed valve operated by the solenoid. The normally
closed valve has a gas inlet connected to the gas source which
leads to the gas inlet of the primary valve body and a gas outlet
which is connected to an enlarged chamber in the primary valve
body. Upon activation of the solenoid, the normally closed valve
of the electronic multi-valved means opens and gas enters the
enlarged chamber whereby the plunger in the primary valve is
shifted and the differential gauge is calibrated.
It is therefore a feature of the invention to provide a
system for measuring an amount of liquid under pressure.
It is a further feature of the invention to provide a system
for measuring an amount of liquid in a cryogenic container.
It is a still further feature of the invention to provide
a novel valve which can be used in the system of the invention.
It is yet another feature of the invention to provide a
system which can be controlled by operation of the valve by
remote means.
Other features and a fuller understanding of the invention
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will be had by referring to the following description and claims
taken in conjunction with the accompanying drawings.
Brief Description of the Drawings
Fig. 1 illustrates a prior art system for determining the
amount of liquid in a cryogenic tank;
Fig. 2A is a cross-sectional view of the novel differential
valve of the invention in the "spool in" position;
Fig. 2B is a cross-sectional view of the valve of Fig. 2A
in the "spool out" position;
Fig. 3 illustrates the system of the present invention for
determining the amount of liquid in a cryogenic tank using manual
controls,
Fig. 4 illustrates as system of the invention which is
automated, and
Fig. 5 illustrates an automated system of the invention
which is actuated from a remote source.
Description of the Preferred Embodiments
Although specific terms are used in the following
description for the sake of clarity, these terms are intended to
refer only to the particular structure of the invention selected
for illustration in the drawings, and are not intended to define
or limit the scope of the invention.
Fig. 1 illustrates the prior art system for an operator to
gauge the amount of liquid in a cryogenic tank. A cryogenic tank
10 having therein a liquid portion 11 and a gaseous portion 12
is provided with a line 13 at the top of the tank 10 and a line
17 at the bottom of the tank. The line 13 leads to one side of
a differential gauge 15 and the line 17 leads to the other side
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of the gauge 15 so that the amount of liquid can be determined
by the difference of pressure on the gauge 15.
The gauge 15 is protected by a blocking valve 14 in line 13
and a blocking valve 14' in line 17. An equalizing valve 19 is
connected to lines 13 and 17 through line 18 intermediate the
gauge 15 and the blocking valves 14,14'.
In operation the operator must open the equalizer valve 19
to allow the gauge 15 to come to equilibrium on both sides of the
gauge 15. After the equalizing valve 19 is opened, the blocking
valves 14, 14' are closed. This will allow the operator to
adjust, calibrate or remove the gauge from the system.
To reverse the operation and place the gauge 15 in service,
the blocking valves 14, 14' must be opened and then the
equalizing valve 19 closed. If this is not performed in proper
sequence in either operation, an inadvertent high pressure will
be seen on one side of the gauge 15 and injure the gauge 15.
As seen in Figs. 2A and 2B, the novel differential valve 20
of the invention comprises a housing 21 having a longitudinal
bore 30 in which a spool or plunger 40 is mounted for
longitudinal movement.
On the upper portion of the housing 21 are a pair of bores
22 in which are placed connectors 23, 23' that form outlets for
the pressurized gases and liquids. The liquid and gases from
bore 30 pass through the openings 36, 36' into chambers 35, 35'
which are associated with the bores 34, 34' of the connectors 23,
23'.
On the lower portion of the valve 20 is the gas inlet
chamber 22' in which there is mounted a check valve 24' with a
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connector 45'. The check valve 24' has a plunger 25' mounted
therein which is normally urged forward against the plunger 40
by a spring 27' which is mounted on lower stop means 32'. An 0-
ring 26' is mounted on the plunger 25' so as to form a seal with
an upper stop means 33' when the plunger 25' is in the most
forward position as shown in Fig. 2B. The gas enters the chamber
30 of the valve 20 through opening 29' when the plunger 25' is
in the position shown in Fig. 2A.
Adjacent to the gas inlet chamber 22' is liquid inlet
chamber 22. Mounted in chamber 22 is a check valve 24 with a
connector 45. The check valve 24 has mounted therein a plunger
25 which is normally urged forward by a spring 27 that is mounted
on lower stop means 32. An 0-ring 26 is mounted on plunger 25
so as to form a seal with an upper stop means 33 when the plunger
25 is in its most forward position as shown in Fig. 2B. The
liquid enters through check valve 24 into the chamber 30 of the
valve 20 by means of opening 29 when the plunger 25 is in the
position shown in Fig. 2A.
The spool or plunger 40 which is located within the bore 30
of the valve body or housing 21 contains a stem 41 which can be
attached for automatic or manual control to move the plunger 40
within the bore 30. The portion of the plunger 40 extending into
the bore 30 is formed to provide two valving areas walls 47b and
47c which cooperate with the 0-rings 42a, 42b, 42c that separate
the pressures and maintain them within the valve bore 30. There
is provided reduced portions 50 and 50' in each valving area and
ramps 46, 46' on which check valve plungers 25, 25' ride
respectively. The cylindrical portions 48, 48' form the surfaces
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on which the plungers 25, 25' ride respectively when the plungers
25, 25' are in the open position as shown in Fig. 2A.
The front of the plunger 40 has a wall 49 which together
with wall 47C forms a notch for the O-ring 42C. The wall 49
abuts a plate 43' which is fasted to the valve body 21 with bolts
44. The wall 49 may be apertured to release any escaped
pressures. The wall 49 abuts the plate 43' when the plunger 40
is in the "spool in" position shown in Fig. 2A.
At the rear of the valve 20 is an apertured plate 43
fastened by bolts 44 through which the stem 41 of the plunger 40
extends. The plunger 40 is provided with a wall 47C form a notch
with the cylindrical portion 48 for O-ring 42A. The wall 47A
abuts the plate 43 when the plunger 40 is in the "spool out"
position shown in Fig. 2B.
Operation of Valve
In operation in a system containing a tank with fluid under
pressure and a gauge as shown in Fig. 3, the valve 20 controls
the operation of the check valves 24, 24'. The spool or plunger
40 has two outside O-rings 42a and 42c which control the escape
of internal gases from inside the valve body. The center O-ring
42b separates the pressures between the two sides of a
differential gauge in the system it is employed (as shown in Fig.
3). Thus, pressure from a liquid or gas which comes through
check valve 24 will proceed through one side of the valve 20.
The outlets of the gas and liquid (gas) are connected to their
respective sides of a differential pressure gauge or transducer.
In the operating condition, the spool or plunger 40 also hold the
two check valves 24, 24' in the open condition as shown in Fig.
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2A.
As the plunger 40 moves to the "spool out" position shown
in Fig. 2B, the center O-ring 42b is moved over opening 36 going
to one side of a gauge. Now both sides of a gauge to which the
outlets are connected are between two of the O-rings 42b, 42c.
This effectively equalizes the pressures to both sides of the
gauge. That is, one side of the tank containing the pressurized
liquid and both sides of the gauge are now connected. As the
plunger 40 is moved from the position shown in Fig. 2A, the check
valves 24, 24' are now being forced by the springs 27, 27' and
the pressures from the tank to the closed position shown in Fig.
2B as the plungers 25, 25' slide down the ramps 46, 46' the
plungers 25, 25' will close before bottoming out on the minimum
cut surfaces 47, 47' of the plunger 40. In the completely closed
positions, the gauge can be removed from the system without any
leakage of gas from the tank.
The gauges can be removed from the system due to
malfunctions of gauge, leaks in the gauge, and for calibration.
There are also new devices which may be incorporated into the
system such as liquid level electronic units and telemetry units
which can replace the older gauges. There must be a means of
replacing one unit for another without draining the entire tank,
or allowing high pressure gas to escape. The present systems
provides such a means.
Moving the plunger 40 in the reverse direction, the plunger
40 will first open the check valves 24, 24' and allow the gases
from the tank to pressurize both sides of the gauge from only one
of the tank lines. The center O-ring 42b is so positioned that
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both sides of the gauge will see the same pressure. As the
plunger 40 is further moved, the O-ring 42b will again cross the
opening 36 and again place the gauge in an operating condition.
Thus, the valve 20 can never be out of sequence and the check
valves 25, 25' stop escaping gas.
A system according to the present invention is illustrated
in Fig. 3 in connection with a cryogenic tank 10 which contains
a cryogenic liquid under pressure. A line 13 leads from the
gaseous portion 12 of the gas inlet connector 45 of the
differential valve 20 shown in Figs. 2A and 2B. A line 17 is
connected from the bottom of the tank 10 to the valve 20 through
connector 45. The liquid outlet of the valve 20 is through
connector 23' which is connected to one side of a differential
gauge 15. The gaseous outlet of the valve 20 is through
connector 23 which is connected to the other side of the
differential gauge 15. A manual means 20a connected to the spool
or plunger 40 of valve 20 through stem 41 controls the position
of the plunger 40.
In the system illustrated in Fig. 3, when the valve 20 is
at zero differential and the plunger or spool 40 is in the "spool
out"
position as illustrated in Fig. 2B, the gauge 15 may be removed.
Fig. 4 illustrates an automated system of the invention.
A tank 50 which contains a liquid 51 under pressure is connected
through line 53 from the gas 52 containing portion of the tank
50 to valve 20 of the invention through the gas inlet 45'. The
bottom of the tank 50 is connected through line 57 to the liquid
connector of the valve 20. The gas outlet 34' of the valve is
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connected through line 53 to one side of a differential
transducer 55. The liquid outlet 34 is connected through line
57 to the other side of the transducer 55. An on/off purge means
62 may be connected to line 57 and through lines 65, 65' to a
computer 68 for pressure calibration. The transducer 55 can also
be connected to the computer 68 through lines 60, 60a. A control
63 for the spool or plunger 40 of the valve 20 may be manual or
connected to computer 68 for remote control.
As shown in Fig. 5, a differential valve 70 is provided
which can be employed in a remote operated closed loop system.
Similar to the valve of Figs. 2A and 2B, the differential
valve 70 comprises a housing 71 having a longitudinal bore 112
in which a spool or plunger 80 is mounted for longitudinal
movement. On the upper portion of the housing 71 are a pair
of bores 72 in which are placed connectors 73, 73' that form
outlets for the pressurized gases and liquids. The liquid and
gases from bore 112 pass through openings into chambers 98, 98'
which are associated with the bores 74, 74' of the connectors 73,
73'.
On the lower portion of the valve 70 is the gas inlet
chamber 72' in which there is mounted a check valve 94' with a
connector 85'. The check valve 94' has a plunger 75' mounted
therein which is normally urged forward against the plunger 80
by a spring 77' which is mounted on lower stop means 72'. An O-
ring 96' is mounted on the plunger 75' so as to form a seal with
an upper stop means 93' when the plunger 75' is in the most
forward position as shown in Fig. 5. The gas enters the chamber
112 of the valve 70 through opening when the plunger 75' is in
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the same position shown in Fig. 2A.
Adjacent to the gas inlet chamber 85' is liquid inlet
chamber 72. Mounted in chamber 72 is a check valve 94 with a
connector 85. The check valve 94 has mounted therein a plunger
75 which is normally urged forward by a spring 77 that is mounted
on lower stop means 72. An 0-ring 96 is mounted on plunger 75
so as to form a seal with an upper stop means 93 when the plunger
75 is in its most forward position as shown in Fig. 5. The
liquid enters through check valve 74 into the chamber 112 of the
valve 70 by means of an opening when the plunger 75 is in the
position shown in Fig. 5.
The spool or plunger 80 which is located within the bore 112
of the valve body or housing 71 contains a stem 81 which is
automatically or manually controlled to move the plunger 80
within the bore 112. The portion of the plunger 80 extending
into the bore 112 is formed to provide two valving area walls 87b
and 87c which cooperate with the O-rings 82a, 82b, 82c that
separate the pressures and maintain them within the valve bore
112. There is provided reduced portions 114 and 114' in each
valving area and ramps 86,86' on which check valve plungers 75,
75' ride respectively. The cylindrical portions 88, 88' form the
surfaces on which the plungers 75, 75' ride respectively when the
plungers 75, 75' are in the open position as shown in Fig. 5.
The front of the plunger 80 has a wall 89 which together
with wall 87C forms a notch for the O-ring 82C. The wall 89
abuts a plate 83' which is fasted to the valve body 71 with bolts
84. The wall 89 contains an aperature 76 and a connector 100
that is connected to gas line 101. The wall 89 abuts the plate
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83' when the plunger 80 is in the "spool in" position shown in
Fig. 5 and is within an enlarged chamber 115 which contains o-
ring 90'.
At the rear of the valve 80 is an aperatured plate 83
fastened by bolts 84 through which the stem 81 extends. Plate
83 has an opening 103 which is connected to a line 102 through
which a gas enters into chamber 118 which contains O-rings 90 and
urges the plunger 80 into the forward position. An 0-ring 82d
in chamber 120 of the plate 83 prevents the escape of gas.
The line 101 is connected to an electronic three-way valve
104. The electronic valve 104 has an exhaust port 106, pressure
port 105, and a solenoid 107. The valve 105 is a three-way
normally closed valve with an inlet 121 from line 102 and an
outlet to line 101.
Gas line 102 is connected to a gas source 109, for example,
a nitrogen tank, through a regulator 108.
The solenoid 107 is connected to receive a signal from a
computer or microprocessor 110 which will process signals from
a telephone or other electronic means 111 to activate the
solenoid 107. When there are no signals, the normally closed
valve 106 will be in the state shown in Fig. 5 and exhaust the
spool chamber 115 to the atmosphere through line 101. When the
solenoid 107 is energized, the pressure of the gas entering
through inlet 121 will then shift the valve 105 so that the gas
passes through line 101 and into chamber 115. An inbalance
occurs since there is now placed the same pressure on the spool
head 89 as found on the other end from the gas pressure entering
aperature 103. This inbalance will operate against the pressure
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on the left of the plunger 80 but because of the larger area it
will overcome that force and cause the plunger 80 to shift to the
left. This shift allows the gauge to be calibrated since there
is now a zero differential pressure on the gauge. Releasing the
signal on the solenoid 107 causes the introduced valve to shift
back to the rest position and exhaust the chamber 115. The
plunger 80 will then be shifted back to the right due to the
original inbalance.
An electronic valve which can be used in the invention is
the Clippard Minimatic valves and manifolds of Clippard Corp.
which are 2-position 3-way control valve model numbers ETO-3M-12-
VDC.
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