CLAIM OF PRIORITY

The present application includes subject matter disclosed in and claims priority to a provisional application entitled "Line Pressure Isolation Valve" filed October 13, 2016 and assigned Serial Number 62/408,000 herein incorporated by reference describing an invention made by the present inventor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to line leak detectors positioned in the pump head of an underground storage tank for fuel dispensation. The present invention is more particularly directed to leak detection and pressure detection along the fuel dispensation system.

2. Description of Prior Art

In typical fuel vending stations, such as a gasoline and diesel vending station, underground storage tanks are used to store hydrocarbon fuels that can then be pumped through the dispensation system via dispensation lines to nozzles/dispensers into a vehicle onboard tank. Underground storage tanks typically have a submersible pump that is activated to provide pressurized force to draw liquid fuel from the underground storage tank, into a pump head past a pump head check valve. Once fuel is in the head (and past the check valve), fuel may then pass into the dispensation lines. An emergency pressure relief top vent may be included in the head to prevent pressures exceeding a certain predetermined threshold, such as above 50 psi. Along the opening for fuel to enter the line, a line leak detector (LLD) may be included in some systems whereby fuel passes from the head, to the line leak detector, into the dispenser line (such as a two inch or lower line) and onto the nozzle.

In a typical gasoline station, submersible pumps in tanks are used in conjunction with an air eliminator valve that opens to allow fluid into the line for dispensation. When a nozzle is closed, the check valve in the dispensation line (such as the pump head check valve) will close to prevent fuel from returning from dispensation line back into the tank system.

Furthermore, by preventing flowback through the dispensation line, fuel, recovered hydrocarbon vapor, and other substances, are prevented from entering the tank system. A column of fuel will remain in the dispensation line from the pump to the nozzle. Given that fuel is typically incompressible in its liquid form, the pressure in the dispensation line will prevent vaporization from occurring assuming no change to the environmental conditions. However, cooling or otherwise lowering the pressure, along the dispensation line can cause the liquid to separate, or components in the line to contract, thus lowering the pressure within the line, and allowing vapor to form. In a high resilient line (not preferred), the amount of contraction of the dispensation line can be great. Preferably, the dispensation line will have low resiliency, meaning that the flexibility volume and size changes are minimized.

Line leak detectors such as the 99 LD-2000 leak detectors provided by Vaporless Manufacturing, Inc. of 8700 East Long Mesa Drive, Prescott Valley, Arizona 86314 solve this problem. Line leak detectors are known in the art, such as the Check valve for a leak detector described in U.S. Patent No. 4,966,190 to Geisinger, Penrod C, incorporated herein by reference, can solve this problem. The mechanical line leak detectors known in the art provide a useful second leak detection point in the fuel dispensation system. Abnormal field conditions such as high line resiliency (high bleed-back), pump pressures over 30 PSI and high head pressures affect line leak detection sensitivity. Additionally, wear affects performance of leak detection over time. These provide the ability of field technicians to adjust line leak detector to compensate for field variables and normal wear.

Certain piping conditions may affect the ability of any leak detector to find a leak. They include high head pressures and high bleed-backs. High bleed-back may occur due to dips in the lines, stubbing for future dispensers, long pipe runs, and extremely flexible pipe. Bleed- back can be interpreted as energy coming back on the leak detector and trying to force the leak detector open. When a leak detector initially is installed and the line pressure is zero psi, the leak detector is in the reset position. When the pump starts, the leak detector allows approximately 1.5 gallons per minute to pass through. In this position, the line is being filled with product and the pressure in the line is slowly rising.

With the line filled with product, the pump still running, the line starts to expand as a balloon might. The expansion of the line is creating energy that is being forced back onto the leak detector piston. Naturally, steel pipe has less expansion than fiberglass pipe, and much less expansion than flexible pipe. Air pockets in the line also raise the bleed-back level, so every effort should be made to eliminate those air pockets by purging the line.

There however exists the issue of being able to determine the pressure on the dispensation line in isolation of the system pressure which may be affected by pump head valves, or other items in the head, or tank system.

It is therefore a primary object of the present invention to provide a means to hold pressure along the line that is independent of a pump check valve for other parts of the pump.

It is a further object of the present invention to isolate downstream pressure from the pump to the line.

It is another object of the present invention to prevent fluid downstream of a pump from draining back into the vessel from which it came.

It is yet a further object of the present invention to retain pressure in a line downstream of a pump and allow the pump head check valve to be free from unwanted pressures.

It is an as yet further object of the present invention to relieve the pressure in a line while preventing pressure against the pump at certain times such as during setup or manual inspection.

It is a further object of the present invention to provide a means to measure the volume of liquid line resiliency and bulk modulus of a line on the dispensation line.

It is a further object of the present invention to reduce line detection false alarms.

It is another object of the present invention to increase the accuracy of line leak detection by decreasing the probability of small leaks signaling an alarm via a separate check valve independent of a pump check valve that can raise the inline pressure and reduce the effects of vapor entrapment.

It is another object of the present invention to provide a check valve to hold pressure independent of a submersible pump.

These and other objects of the present invention will be made clear in light of the further discussion below.

SUMMARY OF THE INVENTION

The present invention is directed to a hydrocarbon fuel dispensation line pressure isolation valve. The valve may be attached to a line leak detector. Preferably the line leak detector includes a narrow longitudinal channel to provide access to line pressure through the narrow channel to be tested from a location outside of line without requirement of opening tank or tank cover to check pressure in line. The system may include an electronic pressure sensor or mechanical pressure switch coupled with the line leak detector preferably on the opposite side of the line leak detector from the dispensation line. The line leak detector preferably also includes shaft providing fluid communication with the dispensation line through the valve. A fastener or cap may be provided at a lower end of the LLD or hydrocarbon fuel dispensation line pressure isolation valve. The fastener preferably includes an aperture allowing fluid communication through the shaft to the pressure sensitive devices. In some embodiments, an upper chamber may be provided in the LLD in fluid communication with the dispensation line, and a diaphragm or other disc or piston may be provided that can communicate pressure to a pressure sensitive device. A pressure switch may be employed on the pressure sensitive device, or a membrane may be provided to measure the pressure.

The present invention further comprises the method of testing the pressure, and determining the dispensation line pressure on a hydrocarbon discharge system. An initialization may occur where an amount of fluid is bled from the system to determine the volume of liquid fluid required to be lost through system to pass pressure from a first (high) threshold) to a second (low) threshold. This may be between 22psi and 14 psi, or otherwise as known in the art or further described below. Once the system is up and running, a pressure test will be run by sensing the pressure on a dispensation line upstream of a vending nozzle. The system will measure the time taken to drop pressure along a dispensation line between two predetermined thresholds. The measuring can be repeated, whereby the pressure is again brought up, as by an upstream supply pump, the pressure in the dispensation line is stabilized and then the system measures the time to drop between the two pressure thresholds. This can be repeated immediately, or over the course of a day, or otherwise, to better reflect the cause of the pressure drop, as between a leak in the dispensation line / system, or other event. By initializing the line, the volume of loss can be determined. The pressure is preferably taken and measured via an isolation valve that closes off the dispensation line form the pump head or other upstream items, and the isolation valve preferably includes a channel in fluid, or other pressure, communication with the dispensation line to provide a reading of dispensation line pressure. The measurement can be taken at the far end of a line leak detector.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described with greater specificity and clarity with reference to the following drawings, in which:

Figure 1 demonstrates a model of a submersible pump and dispensation line of the prior art.

Figure 2 demonstrates a cross-section of a leak detector of the prior art in a reset position.

Figure 3 demonstrates a cross-section of a leak detector of the prior art in a leak sense position.

Figure 4 represents a cross-section of a leak detector of the prior art in a full flow position.

Figure 5 demonstrates an exploded view of an embodiment of the present invention.

Figure 6 demonstrates an exploded view of another embodiment of the present invention.

Figure 7 demonstrates a cross-section of a leak detector of an embodiment of the present invention in a leak sense position.

Figures 8 A and 8B demonstrate a screw fastener of a preferred embodiment of the present invention top view and cross-sectional side view. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to a line pressure isolation valve. The present invention allows read of line pressure through an orifice or channel in the leak detector through a valve via a tube and/or longitudinal hole that may be provided in a screw, or other fastener, or other portion of the bottom of the leak detector, to provide small access to the line pressure for reading pressure either mechanically or electronically. This will allow pressure to be monitored without the need to open the system to ambient pressure or air and allow identification of leaks in dispensation line with constant monitoring, rather than regular checking by opening head, etc.

Referring to Figure 1 , a typical fuel dispensation system at a fuel vending station would include an underground storage tank, such as tank 100. Submersible pump 2 is present toward the lower end of tank, but not typically at the very bottom of tank, to avoid picking up phase separated water or other liquids at bottom of tank. Fuel in liquid form flows up pump line 4 into pump head 10. Submersible pump 2 is powered by electrical line 6 that is supplied power through power supply 12. Power supply 12 may be a typical 220V alternating current voltage from the building or any other supply of power. A starter and capacitor will typically be used in this system. Pump head 10 includes pressure relief valve 14 as well as a check valve 16.

Optional pressure relief may be provided at top or via pressure emergency relief 14a.The pressure relief is often set at around 20 psi within the head and prevents pressures from exceeding 50 psi. The check valve prevents flow back into the tank from the head or dispensation lines. Once fuel enters the head, fuel then passes through leak detector 20 through an opening for fuel to line 24 passing by a boss seal ring 22 into dispensation line 30. Typical dispensation lines known in the art are approximately two inches, and may be half an inch to one and a half inches to three inches as needed. Nozzles and dispensers not shown. The pump line 4 could also be a two inch pipe while the electrical conduit therein may be one and a half inches with wiring for electrical supply to submersible pump. Shaft 8 may be a four inch wide shaft which may be threadedly engaged into the top of the tank.

Line leak detectors (LLD), such as the improved leak detector of the present invention, replace the necessity of, or reinforce/provide redundancy, the use of the pump head check valve, or may be used in conjunction with the check valve. The LLD may provide backup, and/or otherwise further support to prevent backflow into tank. Pumps typically produce upwards of 30 psi, and main check valves are often set around 20 psi. A leak detector in the prior art and of the present invention may open at about one quarter psi differential against back sealing pressure. Pressure is held on the dispensation line via the leak detector check valve and the leak detector check valve typically responds by opening only to pump pressure within the head. The present invention provides for continuous line leak detection by keeping the line pressurized to avoid vapor pockets providing a differential pressure in the line system. Prior art systems can test for leaks after each dispensation, or when all pumps are turned off. Generators known in the art may be tested on a monthly basis, whereas other systems, such as boiler tanks, may only be tested once or twice a year. Certain intermittent pressure sensing for leak detection may take hours or even up to days. The leak detectors of the present invention maintain fluid in the dispensation line and prevent vapor buildup in the dispensation line which may desensitize the line.

Preferably, at least 5 psi is kept in line at all times, as 5 psi is known as a vapor pressure of hydrocarbons under certain conditions. However, in certain circumstances, the pressure on the line will necessarily need to be held above the vapor pressure to avoid gassing out of

hydrocarbons and therefore leading to false alarm leak detections. Reid vapor pressure may be set from 1 to 2 psi or, depending on time of year, vapor pressure may be set as high as 14 psi or other pressures known in the art.

The typical pump head includes a bowl to receive incoming fuel from tank. Bowl may include a check valve that may open at a differential of very low 1 to 2 psi and a pressure relief over 20 to 30 psi to allow fuel to flow back into tank from dispenser. When check valves fail, the pump head check valve may be left open and head pressure from pump will reduce and cause flow back into tank. The check valve in the line detector provides a way of keeping pressure in the dispensation line, and may also prevent hydraulic shocks along the line. Line detectors, as known in the art, may react poorly to shocks along the line as fuel is run down the dispensation line and reflects, or echoes, back through the dispensation line providing a pressure wave shock that may open the leak detector pin, as will be described further below. The One- Way Poppet Flow Path isolates pump turbulence from line leak detection at pump start-up. The hardened stainless steel poppet does not dimensionally change because of thermal conditions encountered during station operation (precision metering change is insignificant down to -20° F). The reduced surface area of the piston significantly reduces the surface area exposed to hydraulic line shock.

The line leak check valve isolates hydraulic shock from the pump components. A primary concern of the present invention is to provide an isolation of the head pressure from the delivery dispensation line pressure. By isolating the dispensation line pressure, leaks or failures of the dispensation line can be identified. This identification of dispensation line issues can be made without respect to leaks elsewhere upstream in the system, such as pump head check valve failures.

Typical leak detection of the prior art, such as the Vaporless Manufacturing Inc. LD-2000 leak detector may be better understood referring to Figures 2-4. As seen in Figure 2, an electric line leak detector is presented, here is reset position. Leak detector 20 includes housing 104 that is connected to the basket 101 via threading 1 1. Pressure from pump via fuel is provided through the side along fuel flow line 1 10. The source may be as high as 30 psi. As shown in Figure 2, the leak detector is in a reset position. When the pressure falls to approximately 3 psi and the pump has been turned on, the piston assembly is forced down, to where the poppet cross hole 125 is aligned halfway with the bottom of the head 144 of the metering pin 124 (as can be better seen in magnification box 130). Fuel passes by pin downwards into outlet 120 to provide supply to dispensation line 30. Line leak check valve here is shown closed 122 and pressure relief 132 is shown. Pressure relief in valve, may be set at 50 psi to allow for thermal expansion and relief of pressure through valve. In the reset position, the leak detector allows approximately three gallons per minute to flow into the line. Pressure causes poppet 116 to move upward in shaft 114 and pressurized chamber 1 12. When chamber is pressurized, poppet moves up providing for sensing in line 102. Check valve 122 includes spring 128 biasing poppet upwards. O-ring boss 126 provides a seal to direct flow into line and isolates the line from pump. The pin and poppet of the present invention are typically made from a hardened stainless steel to provide thermal density and reduce wear. Chamber and piston along line equalize the pressure in the system. Pin 124 may be affixed to the basket.

In the present invention, cylinder piston screws into housing to form isolated chamber. Fluid communication path is provided so that pressure moves the piston up and down, relative to the pin. Alignment shaft moves up and down with pressure differential. Shaft may be affixed to the piston, but free float relative to the spring/guide. When pressure is lower than the threshold pressure (preferably at or above stability pressure) the device will work. Once the pump is shut off, pressure should stabilize in the dispensation line to a lower threshold. This stabilization will give a reading of the pressure loss. A reading is made and can communicate with a controller to restart pump to check consistency of dispensation line pressure loss (e.g. leak). For instance, if there is thermal pressure loss, a single refresh of the pump pressure into the dispensation line will be able to stabilize. A different pressure drop profile can be determined based on time of drop pressure. The invention may also be used to isolate and thereby maintain the pressure in ta dispensation like, regardless of leak detection. The system may also be used to monitor the pressure in the dispensation line from intermittent use of liquid and gas dispensation. The system can also allow for auto-shut off of pump for refill, while maintaining line pressure. The invention also isolates the dispensation line independent of upstream/ head (valve) pressure, and can be used to maintain the priming of dispensation line.

As can be seen in Figure 3, line leak detector 20 is in a leak sense position. When line pressure rises due to pump supply, the piston assembly moves up so that the poppet cross hole

125 is aligned directly with the pin 124 head 144. The leak detector allows approximately two gallons per hour to flow into a line at this leak sense position as system transitions to open for fuel supply. At this point, there is a risk of hydraulic shock against the check valve and poppet, due to the slowdown of supply during leak sense position. By reducing the flow rate to two gallons per hour, the system can automatically sense a leak of two gallons per hour or more. If there is a leak of two gallons per hour (GPH) at this point, there will be pressure buildup in the line that can be sensed. Fuel pressure is provided in the flooded bowl to bias and force poppet upward. When there is a leak over two gallons per hour, the flow will not cause the poppet to move any further, and the leak detector will not open. In this way a failure to deliver fuel to the nozzle indicates a leak upon the line, and the leak detector prevents any further fuel flow into the leaking dispensation line. The leak detector typically takes approximately three seconds to move from reset to leak sense position to full flow position (as later described in with reference to Fig. 4).

As can be seen in Figure 4, leak detector 20 is in full flow position. When the leak detector passes the line, the piston assembly is forced to full open position allowing full pump pressure to flow through the leak detector into the line. Spring typically opens about 1-1/2 pounds. The fuel flow through the basket as shown in cross-section 4a passes through flow through holes that are approximately 1-3/8 inch with 5/8 inch holes. The entire housing 104 will typically be approximately two inches in diameter.

To prevent inflow of ambient air or water vapor into line, with the line filled with product, the pump still running, the line starts to expand as a balloon might. The expansion of the line is creating energy that is being forced back onto the leak detector piston. Naturally, steel pipe has less expansion than fiberglass pipe, and much less expansion than flexible pipe. Air pockets in the line also raise the bleed-back level, so every effort should be made to eliminate those air pockets by purging the line.

Further, a leaking check valve in the turbine, defective submersible pump pressure relief, or a defective bypass valve will allow the line system to depressurize, resetting the leak detector. Drain back into the tank and thermal contraction will cause vapor pockets to form. Vapor pockets increase the length of time it takes for a leak detector to open to full flow. Pump problems such as these result in slow flow and technical support calls. The resulting service costs and customer dissatisfaction are not preferred.

If a leak detector fails to find a two or three GPH leak, the leak detector is not staying at the leak sense position, but instead is going through to full flow. If, when testing the leak detector, the pressure gauge shows a starting pressure of 0 psi and continues to pump operating pressure without hesitating at leak search pressure, the piston assembly may not have completely reset. If this occurs two times in a row; you should (1) turn the pump off, (2) bleed the line pressure to 0 psi, (3) remove the vent line, (4) push the piston assembly down. Turn the pump on and re-test the leak detector to assure it finds a leak.

If, when testing the leak detector, LLD hesitates at leak search pressure but does not hold in leak search position, an adjustment to the piston assembly may be made. The purpose is to make the leak detector more sensitive to a leak. The piston assembly consists of a piston, hollow shaft, spring, and metering poppet. While turning the retaining nut of this assembly, you are turning the whole assembly. The metering poppet is what contacts the metering pin of the leak detector while in the reset position and the leak search position. The metering pin will never move. By changing the position of the metering poppet to the pin, the flow rate will change when adjusting. This also changes the step through time of the leak detector.

Referring now to a preferred embodiment of the present invention as shown in Figure 5, leak detector 20 is shown in exploded form. Leak detector housing 104 is shown to incorporate the various components that are shown in exploded form. A lower boss O-ring 226 fits around the lower end 227 of housing. A basket O-ring 126 is provided to engage the basket. The check valve 304 fits therein and provides for the flow as was shown prior. The pin 124 may be shown. A check valve seal 306 provides a seal around check valve. A check valve piston 308 provides for further function of the check valve. A relief valve 310 may be provided for pressure relief when a high end pressure on dispensation line exceeds some threshold, such as 29 psi coming back from dispensation line over and above the pressure coming from the pump head. Check valve spring 316 is similar to spring 128 from prior figure to hold check valve in place. A retainer 312 such as a check valve spring, as is known in the art, is provided to hold the spring in place. Components of the present invention will typically include a specialized screw 320. In some embodiments, the screw might be one useful in the arts, such as in 8-32 by 3/8 inch screw. The screw will have a bore hole drilled directly and longitudinally through the center to allow communication of the dispensation line pressure through and into a pressure pickup tube 302 that then communicates with a fitting 300 that can sense the pressure downline. When leak detector 20 is assembled, pressure is otherwise sealed and when fuel is not flowing through system, there remains communication through bore hole in screw through pressure pickup tube and to fitting 300 to test line pressure out. Fitting 300 may utilize fasteners known in the art, such as the threaded 1/4 inch NPT threading.

Whereas the prior embodiment shown in Figure 5 can be used with various electronic pressure sensors, the embodiment shown in Figure 6 is more of a mechanical switch pressure sensor. As can be seen in leak detector 20, housing is provided to hold various components therein. Lower boss O-ring 226 fits in a similar fashion to the prior embodiment. Cylindrical seal ring 402 provides a seal for the check valve along with flange nut 404 to fit with piston 406 and provide a piston shaft seal 408. Shaft 410 provides for the fluid communication pressure from downstream fluid dispensation fluid line. A cylindrical piston 412 provides for further housing of parts as described below. Seal shaft 414 fits into upper spring guide 416 which provides for poppet return spring 418. Poppet return spring 418 biases pressure against poppet to allow for leak detection. Lower spring guide 420 provides for further guide to spring and fits around poppet return spring 418 and over guide 416. Alignment shaft 41 OA is in communication with shaft 410 to provide for pressure into upper chamber 401 (Note: that upper chamber 401 is preferably separated and isolated form piston chamber 1 12 of Figs. 2-4). Further spring 424 includes upper spring guide 422 and lower seal guide 426. The lower part of the mechanical line leak detector includes shaft seal 428 fitting within basket O-ring 430 and basket check valve 434. Check valve seal is provided along with a check valve piston 438 and optional pressure relief valve 440. A check valve spring 446 operates in the same manner and is held in place by spring retainer 442. Specialized hole bored screw 450 is also provided. In this embodiment, screw 450 includes a bore hole which screws into alignment shaft 41 OA and provides pressure through screw into alignment shaft 41 OA which is then threadedly attached to shaft 410 and further attached into upper chamber 401. Pressure from dispensation line passes through screw 450 and shafts 41 OA and 410 into upper chamber 401. While there maintains pressure in dispensation line, diaphragm 403 is biased against pressure sensor switch 405 in pressure sensor piston 400. While the pressure is up against the pressure switch, a signal is sent along signal line 407 indicating that the system is properly pressurized, and there are no leaks detected downstream in the dispensation line. When there is a failure in the dispensation line, the dispensation line pressure will drop and the pressure sensed in the upper chamber 401 will drop causing the diaphragm to move downward towards dispensation line and lose mechanical communication with pressure switch 405, often indicating a triggering event such as a leak in dispensation line.

By utilizing a specially bored screw in a leak detector system, the pressure of the dispensation line can be checked from the top of a leak detector and otherwise isolate the pressure from the dispensation line to the pump head and any other portion of the system. The system tests while in reset mode when check valve is closed and there should be a static pressure in the system. The specialized bored screw 450 has a hole bored through it longitudinally from head 452 down threaded shaft 451 to bottom 453. The hole in the burred screw is in

communication with the hollow stem of the basket check valve and communicates with the alignment shaft that is communication through the basket check valve. The channel is preferably approximately 3/32nds of an inch through the screw and may be as high as a l/8ths inch diameter. The pressure is in fluid communication to pass through basket, through tube, to seal. In this way, one can read the line pressure independent of the check valve. Preferred pressure in the line is preferably between 5 and 50 psi, with a minimum psi to prevent vapor gassing out of fuel. Lead vapor pressure to off gas vapor from liquid fuel will depend on fuel additives, fuel blend, and other conditions of the system. The present invention provides for enhancement to line leak detection, particularly with the electronic line leak detector as shown in Figure 5.

Lower boss tightens as O-ring is threaded. O-ring slips on to allow LLD to be screwed in smooth finish for a liquid tight seal. Interior sensor is preferably within the explosion proof housing in direct communication with line pressure. The housing preferably is UL (Underwriters

Laboratories) explosion proof rated via the housing and does not include electronics in communication mechanically directly with the line pressure for any of the liquid fuel.

As can be seen in Fig. 7, system in leak sensing position is shown. Leak detector 520 includes channel 550 bored through the system, passing check valve and piston (possibly through pin) and reaching an upper portion of the LLD. In the embodiment shown and describe din Fig. 6, an upper chamber 401 may be provided. The upper chamber will be isolated from chamber 1 12. Pressure may move a diaphragm up to connect with pressure isolation switch 505. The channel provides for fluid communication of the fuel in dispensation line through a narrow channel in the LLD to allow detection of pressure therein. This channel may provide for fuel to flow and be stored within the channel. Conversely, the channel may provide for pressure communication with a membrane. The pressure sensor may be at bottom, however, it is preferred that the sensor (or sensor switch) is further removed from fuel line for safety (and access) purposes. Alternatively, the channel may be filled with a incompressible substance and lightly connected (but not intermixing) with fuel. This may be a channel filled with water, mercury, etc. and substances known in the art to provide pressure transfer through a channel for sensing. It is preferred that the sensor be at the top of LLD. Electronics can be safely employed at top of LLD, an may be housing in pump head, or outside of pump head, via access of protruding LLD.

As can be seen in Figures 8A-8B, a preferred embodiment of hole bored screw is shown. Screw 551 may be a standard Philips head, but can be any fastener known in the art to be amenable to inclusion in a check valve. This can include bolts, nails, caps, plates, etc. The screw head 552 includes hole 555 bored through. As can be seen in Figure 8B, bore channel 560 is set longitudinally through screw 551 to allow fluid communication of downstream fuel in dispensation line to share pressure information through screw, (through LLD,) and to pressure sensor. Channel 560 mates with channel 550 to provide access to pressure sensing above LLD.

The present invention also includes a method to control pressuring system in housing in directed fluid connection with the line. If high voltage is required, the housing will be explosion proof. If low voltage is used, the voltage will be maintained at a low enough rate so as not to heat or spark or otherwise cause a risk of igniting the fuel. In an alternate, the sensor may be put within the housing a very low voltage. Preferably, the sensor will be screwed to the top of the housing. In some instances, a first fixture will be placed on top of the leak detector leading to an electronic pressure sensor that is either in fluid communication or otherwise leading pressure at the line leak detector top fitting. It may be possible to have a wireless remote sense of line pressure. For instance, fitting may include a protruding antenna that may provide a RP or Wi-Fi signal. In another embodiment, a pressure transducer within the housing can sense a mechanical switch when pressure is present and thereby send some signal to a central processing unit. A digital signal can be sent therefrom, wirelessly or wired to a central processing system. Signals can be sent on a regular basis or a continual basis, such as every second, every 30 seconds, etc.

In order to set up the system, typically the dispensation line is flushed to provide a solid liquid fill of dispensation line. Two pressure points are indicated and stored in the system memory to understand how long a pressure drop in the line takes. For instance, when pressure drops in the line from 20 to 15 psi, possibly due to ambient conditions, the system will give a specific time for the pressure drop. Multiple tests can be conducted to determine whether or not the pressure drop time is faster than expected given ambient conditions.

The present invention includes a method for calculating a leak rate. The volume of fluid loss can be determined between two (pressure) set points. This can be found by timing the amount of time it takes to move between two set points under a constant temperature, pressure, and other ambient conditions. This may be determined manually by bleeding the dispensation line to determine the volume necessary to drop pressure in dispensation line between two set points. The amount of time it takes to drop down to the second set point of pressure will determine the rate of pressure loss. Accounting for variables such as temperature, thermal expansion, coefficients of expansion, time barometric pressures, etc., one can see whether or not the drop between the two set points indicates a leak or other issue with the line. Furthermore, the blend of the fuel will be taken into account.

Typical thermal contraction/expansion will cause dispensation line to drop in pressure, to as low as around 0 to 3 psi. Prior art testing of dispensation line typically occurred whenever an authorization ends. Tests were approximately at three gallons per hour at 10 psi as required by a catastrophic line leak test demanded by the Environmental Protection Agency (EPA). Monthly tests down to 0.2 gallons per hour may be conducted. Such monthly testing typically takes 1-5 hours. An annual test to the sensitivity of 0.1 gallons per hour may have been used to certify the system as tight. The present invention provides for more frequent and more sensitive testing.

The present invention and line leak detectors sense whether pressure falls below a preset pressure, for instance 5 psi, 14 psi, etc., depending on fuel blend and atmospheric conditions. Once the pressure falls below the preset, leak detector initiates a line test. The pump can turn on, the line system will raise the pressure in the dispensation line to 30 psi (or 22 psi, or other preferred stable pressure on dispensation line) and stabilize, and then the system is sealed by the isolation valve and a test is determined to see how long it might take for pressure to drop to a second preset. Such testing can be done continually and can be made on a frequent basis, for instance every minute. A pump is turned on once the lower threshold is reached and the test is repeated. The system can thereby be tested via running pressure into the dispensation line multiple times and determining how long pressure drops take.

In order to initialize system, upon install or setup, the installer will measure the amount of fluid to drop the pressure within line when removed to drop the pressure down to a set point such as 14 psi (or vapor pressure, or above vapor pressure). Dispensation line will be pressurized (typically via pump), and then the installer mechanic will draw out fuel from dispensation line to determine the amount of volume loss from a drop from typical dispensation line pressures down to the preset, such as 14 psi. The preset is set above vapor pressure of the line. A stabilized pressure for the system could be higher such as 22 psi so that the system can determine the pressure loss in a full fuel fluid line. In this manner, the system can know how much fuel, such as how many milliliters of fuel, will be reduced from dispensation line to drop between two set points. For instance, two set points can be 22 psi down to 14 psi. In this way, one can give the time and volume of a leak rate. Depending on ambient conditions, therefore system can differentiate from thermal drops and a leak. Repeated testing allows for determination of leak, and necessarily an estimate of the volume loss over time. A leak will typically be shown by a constant drop in pressure without stabilization, whereas a thermal change in pressure will fluctuate and modulate depending on time of day conditions, etc.

Leaks may take some time to initialize from a first pressure setting to a second pressure setting. The time and volume of the leak will be noted. For instance, a catastrophic first threshold can be set at 3 gallons per hour (at 10 psi). A second pressure threshold up to a continuous leak test can run between 3 gallons per hour down to 2 gallons per hour, 1 gallon per hour, 1/2 gallon per hour, as well as 0.2 gallons per hour or lower and thereby calculate the leak rate.

Continuous testing of the line keeps or maintains dynamic pressure in the line. Method includes turning on pump at 14 psi to test line pressure. The pressure in line is preferably over the Reid vapor pressure to ensure a dynamic vapor pressure does not mess with the volume measurements of inline testing. If hydrocarbon vapor forms, the test may not be useful to determine a leak. The present invention includes a method to prevent formation of a vapor pocket in the line, and to ensure line pressure does not drop below the Reid vapor pressure, by isolating the pressure in the line. The present invention uses an electric line leak detector in conjunction with an isolation valve. The electronic line leak detector can use a pressure sensor.

A typical vending station will include a dispensation line that may be as long as 175 feet with 4-6 dispensers/nozzles. Typical lines are made of fiberglass and steel, and have various connectors which can add resiliency to the line. A "tight" site can include a 125-175 milliliter bleed back for line resilience. Flex connectors, steel tubes on the submersible, lines swelling with pressure, fuel dispenser connectors, etc., provide for unwanted resiliency. Up to 250 milliliters of resiliency is not uncommon due to multiple flex connectors. Further resiliency above this is typically due to trapped vapor at a high resiliency dispensation system with spacing and vacuums forming to provide low pressure to allow vapor to form.

With the electric line leak detector, leak detection rates can be more sensitive to provide more accuracy in a shorter time. Line leak detection can be provided even in high resilient lines. The window of resilience can be narrowed, such as between 22 psi to 14 psi to something more narrow such as a 22 psi to 18 psi and the window can be reduced to a narrow window from 20 to 10 minutes. By maintaining a narrow window, multiple tests can be performed and maintain repeatability of testing to maintain low error in leak detection.

A leak detector node (LDN) can provide data in communication with or without power to determine pressure in port and optional pressure out. The controller allows the pump to turn on additional times and monitor the pressure in dispensation line. By monitoring the pressure on a continuous basis via leak detector isolation valve, the system can monitor changes in pressure in delivery lines at a threshold pressure of approximately 20 psi in line. This is a benefit over pump head detection as it is better to look at the pressure in the discharge side rather than in the leak detector due to the geometry of the fuel flow through the leak detector (corners, turns, etc.). As a higher volume is dispensed through the leak detector becomes more differential and harder to read. By isolating the dispensation line pressure, a direct linear pressure from the line against the bored screw can provide better and more sensitive testing. The present invention includes a device to measure the pressure downstream of a pump isolated from pump head. The invention further includes a method for measuring between two various pressure set points when the pump is turned off through a specific window of two set pressures to provide a leak rate with time and volume noted to understand the leak rate of fuel leaving the line. The invention provides for repetitive testing by restarting pump to measure the same length of time to move between various set points to therefore determine whether leaks are due to thermal expansion/contraction or an actual leak in the line.

The leak detector may have a smaller diameter piston area than the poppet to which it is attached. This smaller piston area keeps the leak detector in the fast fill position (3 GPM) to a higher line pressure while compressing vapor pockets and expanding flexible pipes faster. This means less time to full flow. The leak detector does not have to completely reset (as with competitive leak detectors) for the poppet to be forced into the reset mode at pump start-up. With a reduced piston size, as an example, there is one-fourth the fuel volume to replace when in leak search and one-fourth the fuel volume to return to the line when the pump turns off. This combination makes for a more responsive and faster leak detector. Less volume to leave the line for the leak detector to reset and catch leaks. Less volume to fill and provide full flow for dispensing. By isolating the pump head check valve from the line, the present invention can reduce service calls for diagnostic for false alarms when the pump head is broken. Annual inspections for pump head check valves are inadequate for determining leaks. The present invention will hopefully eliminate the need for service calls for pump head valve failures. The present invention is designed to increase the accuracy by not requiring a submersible check valve to function. By isolating the dispensation line, the test can be done with or without a functioning check valve. The material and design of the system with line pressures moving from wide to narrow allow for the dispensation line to be self-cleaning as fuel flows through and will not otherwise affect the pressure sensed by the burred screw.