Automatic shut off for gravity filling system for liquid storage tanks

In a liquid loading system for the gravity loading of a liquid storage tank from a tank truck the present invention provides an improved mechanism for interrupting the flow of liquid when the level of liquid in a tank rises above a predetermined level. The structure includes a valve in the fill line which is moveable between an open position and closed position. A pressure responsive latch means is provided for releasably locking the valve in the open position. A vent passage communicates between the pressure responsive latch means and a predetermined level below the upper end of the underground storage tank. A vacuum passage communicates between the vent passage and a vacuum source in the fill line. The flow of liquid through the liquid fill line generates the vacuum in the fill line in the area of the vacuum passage. Until the level of liquid in the underground tank rises above the end of the vent passage, atmosphere from within the tank is drawn into the vacuum passage from the vent passage. When the level of liquid in the tank rises above the end of the vent passage the vacuum pressure is applied to the pressure responsive latch means to release the valve which moves automatically to the closed position to interrupt the flow of liquid.

FIELD OF INVENTION 
This invention relates to a system for the gravity filling of liquid 
storage tanks from tank trucks. In particular this invention relates to a 
tank truck storage system incorporating an automatic shut-off mechanism 
which prevents over-filling of storage tanks such as underground storage 
tanks. 
PRIOR ART 
Considerable difficulty has been experienced in attempting to prevent 
over-filling of underground storage tanks at gasoline service stations 
with the result that spillage is common during the loading of the 
underground storage tank. This spillage is wasteful, hazardous and causes 
environmental pollution. 
Numerous attempts have been made to overcome this difficulty. However, in 
most of the prior structures which have been proposed, extensive 
modification of existing equipment is required. 
For a number of years an automatic shut-off nozzle has been used in 
gasoline service stations for automatically shutting off the supply of 
gasoline from a gasoline pump to a vehicle when the level of liquid rises 
above a predetermined level within the tank. This type of nozzle is 
described in U.S. Pat. No. 3,196,908. In this device a vacuum pressure is 
established by means of a venturi section within the nozzle. In this 
apparatus, however, the liquid passes through the nozzle under the 
pressure of the delivery pump so that no difficulty is experienced in 
drawing a sufficient vacuum at the venturi to activate the pressure 
sensitive latching mechanism to release the closure valve when the level 
of liquid rises above the end of the vent line which is located within the 
vehicle gasoline storage tank. Although it has been known that this device 
has operated successfully for some considerable time, it is not possible 
to employ this system when gravity filling a liquid storage tank such as 
an underground storage tank because of the low velocities involved. 
However, it has been discovered that the line extending from the tank 
truck of the vehicle to the underground storage tank is a syphon in which 
at certain locations there is a sufficient negative pressure to draw a 
vacuum sufficient to activate the latching mechanism. This vacuum has been 
utilized by extending a vent line through the fill line, one end of which 
opens into the underground storage tank at a predetermined level within 
the tank and the other end of which communicates with a pressure sensitive 
latching mechanism. A vacuum passage extends between the vent line and the 
fill line in order to draw a vacuum in the vent line. The vacuum will 
normally be vented from within the tank until the level of liquid in the 
tank rises above the lower end of the vent line whereupon the vacuum will 
be drawn on the pressure sensitive latching mechanism to release the 
latching mechanism, thereby causing the shut-off valve to move to the 
closed position interrupting the flow of liquid into the storage tank. 
SUMMARY OF INVENTION 
According to one aspect of the present invention, there is provided, in a 
liquid loading system for the gravity loading of a liquid storage tank 
from a tank truck having at least one liquid shipping compartment, a 
liquid fill line opening from the shipping compartment and connected to a 
liquid input passage of the liquid storage tank, the improvement of; valve 
means in said line movable between an open position in which the line is 
open and a closed position in which the line is closed to interrupt the 
flow of liquid to the storage tank; pressure responsive latch means 
associated with the valve means for releasably locking the valve in the 
open position; vent passage means having a first end communicating with 
said pressure responsive latch means and a second end opening into the 
storage tank at a predetermined level below the upper end of the tank, and 
vacuum passage means communicating between the vent passage means and the 
interior of the flow line whereby the flow of liquid through the fill line 
during the filling of the storage tank draws a vacuum in the vent line 
which is insufficient to activate the pressure responsive latch means 
until the level of liquid in the storage tank rises to close the other end 
of the vent line whereupon the full vacuum is applied to the pressure 
response latch means to release the valve which then moves to the closed 
position. 
According to a further aspect of the present invention, the first vent 
means of the liquid loading system described above comprises a vacuum 
probe receiver tube mounted coaxially within the upper end of the drop 
tube by means of at least one rib extending radially inwardly from the 
drop tube, the vacuum probe receiver tube opening upwardly, a liner tube 
extending downwardly from the adapter coaxially outwardly of the drop tube 
to form a passage therebetween which terminates at said predetermined 
level within the tank, the first vent passage extending longitudinally 
downwardly from the upper end of the drop tube and radially outwardly 
through the radially extending arm and opening into the passage formed 
between the liner tube and the drop tube to terminate at a predetermined 
level within the tank, the second vent passage means including a vacuum 
probe mounted at its upper end in a coupler and projecting coaxially with 
respect to the coupler and adapter to fit within the open end of the 
vacuum probe receiver tube.

With reference to FIG. 1 of the drawings, the reference numeral 10 refers 
generally to a liquid loading system according to an embodiment of the 
present invention. In this system, liquid from a shipping compartment 12 
of a tank truck 14 is discharged through the valve 16, filling hose 18, 
coupler 20, adapter 24 and fill pipe or drop tube 26 to underground 
storage tank 28. The underground storage tank 28 is provided with a 
conventional vent line 30 which communicates between the tank 28 and 
atmosphere. 
The system described above is the conventional filling system wherein the 
operator must remain in attendance during the filling operation and must 
close the valve 16 immediately on receipt of a signal that the underground 
storage tank 28 is full or substantially full. Systems have previously 
been developed in which the rising level of liquid in the tank serves to 
signal the fact that the tank is substantially full and in some known 
systems there is provided an automatic control for stopping the flow of 
liquid when the level rises above the maximum required fill height. The 
present invention achieves the required automatic shut-off by providing a 
valve member generally identified by the reference numeral 32, a pressure 
responsive latching mechanism generally identified by the reference 
numeral 34, and a vent passage 36 together with a vacuum passage 38. 
In use, liquid flowing through the coupler 20 and fill pipe 26 draws a 
vacuum in the vacuum passage 38. Atmosphere from within the underground 
storage tank 28 is drawn upwardly through the vent passage 36 and into the 
vacuum passage 38. This condition will continue to exist until the level 
of liquid in the tank rises above the lower end of the passage 36 
whereupon the vacuum pressure in the line 38 will be transmitted through 
the passage 40 to the pressure responsive latch mechanism to release the 
latch mechanism to cause the latch mechanism to release the valve member 
32, whereupon the valve member 32 will move to a position closing the 
through passage of the coupler 20 thereby stopping the flow of liquid. 
The structure of the adapter 24, drop tube 26 and the first vent means 
which forms the lower portion of the vent passage 36 is illustrated in 
FIGS. 2, 6 and 7 of the drawings. As shown in FIG. 7, the adapter member 
24 is threadably mounted in the upper end of the riser pipe 42 which is 
secured with respect to the underground storage tank 28 by means of a 
collar 44. A liner tube 46 has a narrow flange at the upper end thereof 
which projects radially outwardly over the upper end of the riser pipe 42. 
The liner 46 extends downwardly into the storage tank 28 to a 
predetermined level below the upper end of the tank 28. The liner 46 has a 
plurality of dimples 48 located about the periphery thereof and projecting 
inwardly therefrom. The dimples 48 serve to center the drop tube 26. The 
drop tube 26 has a narrow flange at the upper end thereof which projects 
radially outwardly to a position overlying the flange of the liner tube 
46. The flange at the upper end of the drop tube 26 is formed with a 
plurality of passages 50 which open therethrough. A resilient annular 
sealing ring 52 is located above the flange of the drop tube and has 
passages 54 located therein which are aligned with the passages 50 of the 
drop tube 26. 
A vacuum probe receiver generally identified by the reference numeral 56 is 
located in the adapter and is clamped between the shoulder 58 of the 
adapter and resilient sealing ring 52. The vacuum probe receiver consists 
of a receiver tube 60, three radially extending support arms 62 and a 
circumferentially extending ring 64. The vacuum probe receiver tube 60 is 
located on the central axis 66 of the adapter and is supported in this 
position by means of the arms 62 which radiate inwardly from the ring 64. 
Vent passages 68 extend through the vacuum probe receiver tube 60 and each 
of the arms 62 and communicate with a circumferentially extending passage 
70 in the lower face of the ring 64. The drop tube 26 is spaced inwardly 
from the liner tube 46 to provide a vent passage 72 therebetween. As will 
be apparent from FIG. 2 of the drawings, the vent passage 72 communicates 
with the passage 50 in the upper flange of the drop tube, the passage 54 
in the resilient ring 52, and the passages 70 and 68 of the vacuum probe 
receiver member 56. These passages together form the first vent passage 
means which forms a permanent fixture at the underground storage tank. It 
will be apparent that atmosphere from within the underground storage tank 
can be drawn through this first vent passage means until the level of 
liquid in the storage tank rises above the lower end of the liner tube 46 
to close the lower end of the vent passage 72. 
The vent passages which extend through the coupler are best illustrated 
with reference to FIGS. 2 and 3 of the drawings. As shown in FIG. 2 of the 
drawings, the coupler member 20 consists of a body portion 73 and a head 
portion 74 connected to one another at an interface 76. The coupler 20 is 
adapted to be releasably secured with respect to the adapter 24 by means 
of a conventional locking mechanism 78. A vacuum probe tube 80 has its 
upper end secured in the body portions 73 and extends downwardly therefrom 
in alignment with the vacuum probe receiver 56. The lower end of the probe 
80 is centered with respect to the lower end of the coupler by means of a 
plurality of circumferentially spaced arms 82 which extend radially 
inwardly from the side walls of the coupler. As shown in FIG. 3 of the 
drawings, the upper end of the probe tube 80 is located in a recess 86 
within which a manually operated valve mechanism 88 is located. The valve 
mechanism 88 includes a mounting collar 90 and a valve member 92 slidably 
mounted therein. The valve member 92 is urged upwardly away from the upper 
end of the tube 80 by means of a spring 94. The valve member 92 has a seal 
96 at the lower end thereof. The valve member 92 is slidable with respect 
to the collar 90 for movement towards and away from engagement with the 
upper end of the probe tube 80 to close the upper end of the probe tube 80 
as required in use. The vacuum probe 80 has a passage 98 extending 
therethrough which may be closed by the valve member 92 as previously 
described. A further passage 100 opens from the passage 86 to a passage 
102 located at the interface 76. A vacuum passage 104 opens from the 
passage 102 directly into the through passage 106 of the coupler member 
20. The vacuum passage 104 has a portion of reduced diameter at the outer 
end thereof. 
The vent passage 40 of the head portion 74 of the coupler communicates with 
the passage 102 and is therefore in communication with the passage 100 and 
the vacuum passage 104. 
The pressure responsive latch mechanism 34 is illustrated in FIG. 3 of the 
drawings. As shown in FIG. 3 of the drawings, the head portion 74 of the 
coupler has a latching chamber 108 located therein, the upper end of which 
is closed by a head plate 110. A resilient diaphragm 112 is clamped 
between the head plate 110 and the upper end of the latching chamber 108. 
The diaphragm 112 has a passage 114 located therein which communicates 
with the passage 40 in the head. The passage 114 communicates with the 
upper diaphragm chamber 116 by means of a passage 118. 
The latching mechanism includes a ball support member 120 which has a 
plurality of ball receiving passages 124 extending therethrough. A ball 
126 is located in each of the passages 124. A ball retainer member 128 is 
slidably mounted on the outer face of the support member 120 and has a 
stem portion 130 projecting upwardly therefrom. A latch supporting housing 
132 is located outwardly from the retainer member 128. The releasable 
latch assembly is secured with respect to the bottom wall of the latching 
chamber 108 by means of a plurality of mounting screws 134. The ball 
retainer member 128 has a portion 136 of increased diameter at the lower 
end thereof. A ball spacer member 138 is slidably mounted within the bore 
of the ball mounting member 124 and is urged downwardly therein by means 
of a compression spring 140. A peripheral flange at the upper end of the 
ball spacer member 138 serves to limit the downward movement of the ball 
spacer member. The stem 130 of the ball retainer 128 is secured to the 
flexible diaphragm 112 for movement therewith by means of a locking nut 
142. A spring base plate 144 is secured with respect to the stem 130 by 
the nut 142 and a compressing spring 146 bears against the spring base 
plate 144 and the head 110 to urge the flexible diaphragm 112 and the ball 
retainer member 128 downwardly. 
The valve member 32 is in the form of a circular disc having an annular 
sealing member 150 mounted at the edge thereof for engagement with the 
valve seat 152 formed at the interface 76 between the body portion 73 and 
the head portion 74 of the coupler. When the valve member 32 is in the 
position shown in broken lines in FIG. 3, the through passage 106 of the 
coupler is closed to prevent the flow of liquid therethrough. The valve 
member is pivotably mounted by means of a pair of pivot arms 154 (only one 
of which is shown) on a pivot shaft 156 which is mounted to rotate in the 
head 74. The valve member 32 has a valve stem 160 projecting upwardly 
therefrom. The valve stem 160 has a neck portion of reduced diameter 162 
formed with tapering shoulders at opposite ends thereof and a head portion 
164 at the upper end thereof. When the valve is in the open position shown 
in FIG. 3, the valve stem is locked within the latching mechanism by the 
balls 126 which project into the neck portion 162. The balls are prevented 
from moving outwardly by means of the ball retaining member 128. When the 
full force of the vacuum is drawn in the line 40 and transmitted to the 
chamber 116 above the diaphragm 112, the reduction in pressure in the 
chamber 116 causes the diaphragm 112 to move upwardly to compress the 
spring 146. 
The upward movement of the diaphragm 122 raises the stem 130 and the ball 
retainer member 128 so that the enlarged end portion 136 of the ball 
retainer is aligned with the balls 126. The tapered shoulder of the valve 
stem 160 forces the balls 126 radially outwardly into the enlarged portion 
136, thereby permitting the head 164 of the valve stem to drop to permit 
the valve 32 to move to a closed position. As the head portion 164 moves 
downwardly past the balls 126, the ball spacer member 138 follows it and 
serves to prevent the balls 126 from moving inwardly after the head 164 
has passed downwardly therebetween. In order to return the valve member 32 
to the open position, it is manually moved towards the open position, as 
will be described hereinafter, and the valve stem 160 reenters the central 
passage formed in the latching mechanism. The head 164 of the stem engages 
the ball spacer member 138 and forces it upwardly by compressing the 
spring 140. When the neck portion of the stem is aligned with the balls 
126, the balls 126 will be driven inwardly towards the neck 160 when the 
pressure in the vacuum chamber 116 is relieved to the extent that the 
spring 146 pushes the ball retainer member downwardly to force the balls 
126 inwardly towards the neck 162. When the balls 126 are located in this 
position, the valve member 32 will once again be locked in the open 
position. 
The manual resetting of the valve member 32 to the latched position is 
achieved by movement of the reset handle 170 (FIGS. 4, 5). The handle 170 
has a boss portion 172 at the upper end thereof which is pinned by means 
of a pin 174 to the end of the shaft 156. A coil spring 176 has one end 
pinned to the head 74 by means of a pin 178 and the other end 180 is 
secured to the shaft 156. Rotation of the handle 170 in the direction of 
the arrow A in FIG. 4 to the chain line position shown in FIG. 4 tightens 
the coil spring 176. A pin 182 (FIG. 3) projects radially outwardly from 
the shaft 156 and is secured thereto. A plate 184 projects laterally from 
the arm 154 of the valve member 32. As indicated in FIG. 4 of the 
drawings, the handle 170 will rest in the solid line position and will be 
returned automatically to the solid line position by the spring means 
after the resetting of the valve member in the latched position. When the 
valve member 32 is in the closed position shown in broken lines in FIG. 3, 
rotation of the shaft 156 in response to movement of the handle 170 in the 
direction of the arrow A will cause the pin 182 to engage the plate 184 so 
that the valve member 32 will be moved to the latching position in 
response to rotation of the handle 170. 
In use, the operator arrives at a drop location and he connects the coupler 
to the adapter and thereby locates the vacuum probe 36 in the vacuum 
receiver 56. The operator then moves the handle 170 from the position 
shown in solid lines in FIG. 4 to the position shown in chain lines in 
FIG. 4, thereby ensuring that the valve member 32 is located in the 
latched position. The operator then opens the valve 16 (FIG. 1) and liquid 
flows from the compartment 12 of the tank truck to the underground storage 
tank. The passage of liquid through the through passage 106 in the coupler 
draws a vacuum in the line 104. Atmosphere from within the underground 
storage tank is drawn into the vacuum passage 104 through the first vent 
passage means which consists of the passages 102 and 100 formed in the 
head and the passage 98 formed in the vent probe 36, the passages 68,70 
and 52 formed in the probe receiver and its associated sealing ring and 
the passages 50 formed in the upper end of the drop tube and the passage 
72 formed between the drop tube 26 and the liner tube 46. Atmosphere will 
continue to be supplied to the vacuum passage 104 through this system of 
passages until the level of liquid in the storage tank rises above the 
lower end of the inner tube 46. As a routine in the delivery, the operator 
is able to determine whether or not the automatic release of the latching 
mechanism is functioning properly by manually depressing the valve member 
92. This closes the upper end of the vacuum probe member 80 and thereby 
interrupts the venting communication between the vacuum passage 104 and 
the storage tank. As a result of the closing of the passage 98, the vacuum 
drawn in the line 104 is transmitted through the passage 40 of the head to 
the diaphragm chamber 116 and the latching mechanism is thereby activated 
as previously described to release the valve member to permit it to fall 
to the closed position. The valve member 32 will then be located in a 
position bearing against the valve seat 152, thereby interrupting the flow 
of liquid through the passage 104. Having determined that the latching 
mechanism is operating satisfactorily, the operator may release the valve 
92 which will move to the open position under the influence of the spring 
94 and then manually reset the valve 32 to the latched position by moving 
the handle 170 as previously described. This gives the operator an 
indication that the latching mechanism is operating satisfactorily. After 
the valve 32 has been reset in the open position, liquid will continue to 
flow into the tank 28 until the level rises above the lower end of the 
liner tube 46 whereupon the lower end of the passage 72 will be closed to 
prevent atmosphere being drawn from the underground storage tank to the 
vacuum passage 104. This will again activate the latching mechanism in the 
same manner as that described when the valve 92 is closed to release the 
valve member to permit the valve member 32 to move to the closed position 
shown in broken lines in FIG. 3. Consequently, when the level of liquid in 
the underground storage tank rises above the lower end of the liner 46, 
the valve member 32 will be automatically released and will fall to 
automatically close the through passage 106 and thereby stop the flow of 
liquid into the storage tank. 
It has been found that an adequate vacuum is drawn in the vacuum line 104 
of the coupler in response to the passage of liquid unloading from the 
tank truck under the influence of gravity into the underground storage 
tank. 
Various modifications of the present invention will be apparent to those 
skilled in the art without departing from the scope of the invention. For 
example, it may be possible to dispense with the vacuum passage 104 which 
is formed in the body and to communicate directly with the interior of the 
coupler by means of an orifice opening through the wall of the vacuum 
probe member 36. This would have the disadvantage of locating the vacuum 
line downstream of the valve mechanism 88 so that it would not be possible 
to test the system in the manner previously described. These and other 
modifications of the present invention will be apparent to those skilled 
in the art.