Fluid handling – With leakage or drip collecting
Reexamination Certificate
2001-09-13
2004-11-30
Walton, George L. (Department: 3753)
Fluid handling
With leakage or drip collecting
C073S040000, C073S049200, C137S557000, C137S558000, C141S094000, C141S098000, C141S198000, C141S31100A, C220S918000, C340S605000
Reexamination Certificate
active
06823886
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to sumps to contain leakages. In particular the invention is directed to containing leakages of toxic liquids, such as petroleum or other oil based products. A particular application of the technology of the invention relates to protecting the environment from gasoline spills at locations where consumers obtain gasoline at dispensers, pumps and the like.
Current requirements are for periodic testing of leakage around gasoline dispensers at consumer gasoline stations. This means that leakage could occur in between the periods of testing thereby increasing the oil company's potential liabilities. A reason why current dispenser containment designs can not be tested continuously is because the inside of a dispenser containment box or sump can not be filled with liquid. The liquid would most likely rust the many components inside the box, and the regulatory agencies do not allow standing fluid and the manufacturers do not allow for the kind of weight that would expose the dispenser sump.
Visual inspections to see whether the dispenser sump is leaking is impossible. Also it is desirable to change to requiring a higher form of secondary containment and/or monitoring of liquid. A pipe containing the liquid is termed the first form of containment and the wall of the sump is called the second form of containment.
Presently there are no regulations that require a tertiary form of containment or a monitoring of the integrity of the secondary or tertiary form of containment. This may change if a product, method or system is introduced in the industry with a higher degrees of integrity and protection against leakage than the presently known and used systems, methods and products. The present invention is directed to providing that higher degree or level of containment.
Testing in California for gasoline station secondary systems is to be at initial installation, six months later and every 3 years thereafter. The problem that everyone in the industry faces is how to verify that the system is not leaking. If there is leakage, there is a need to easily trouble shoot to identify where the leakage problem is located. At initial installation of a sump with dispenser, testing is easily accomplished by visually inspecting the box from the outside prior to cementing over the entire job-site. The problem now faced by the industry, as a whole is how do you test secondary containment as simply, reliably without major cost to the end user.
The most commonly used method in the industry is to test the dispenser containment with water filling the containment sump up and utilizing very sensitive float sensors to speed up the test. This involves filling a dispenser sump up with as much as 50 to 60 gallons of water. Should a leak be found the most time consuming issue is then locating the leak that can not be viewed from the outside of the sump since the containment unit is buried in under concrete. Finding and repairing a leak is the most time consuming and costly part of the tests. In addition, the water used must then be removed and treated as a hazardous material adding to the cost and complicates the process of testing.
Other methods of testing that have been considered were vacuum and pressure testing of dispenser containment which are not practical in dispenser containment because of the pipe extending upwards through the opening within the dispenser. The only way to pressurize a conventional dispenser sump is to remove the dispenser which costs over $1,000 per dispenser and the shutdown of the station.
Unlike dispenser sumps, tank sumps can be tested under vacuum and pressure because every part contained within a tank sump can be covered without cost. The test is subject to a much more stringent requirement since air can find much smaller leaks involving electrical wiring leaks and smaller cracks in the sump or its accessories. Air testing usually results in finding leaks in areas that are typically not required to tested by regulators.
The present invention is directed to providing a tertiary form of containment and/or providing a simplified means of monitoring substantially easily and/or relatively continuously the second form of containment.
Another issue relating to sumps, revolves around the need for the piping containing electrical lines into a hazardous material area to be buried 24″ below a concrete surface and the pipe must be made of a continuous run or rigid steel conduit. As a result, the electrical fittings are the most commonly damaged fitting. Even flexible fittings are often bent beyond the recommended entry angle 15 degrees maximum.
Typically, the worst situation is when an electrician needs to run conduit to the side closest to inside of a dispenser containment wall. In addition, a typical 90 degrees minimum bend radius may only be 8 inches. To compensate for inability to bring an electrical conduit close to the wall the electrical contractor often over-loops the conduit by 110 degrees and return it back by 20 degrees to align the conduit with the dispenser above the sump. This typically is a very inaccurate method, which then leads the electrical contractor to abuse the penetration fitting to compensate. This leads to failure of a fitting. An easier method would be to bring the conduit through the bottom of the sump as in shallow pans, which alleviate stress to the fittings. However, this also leaves the fitting on a bottom of a sump exposed to fuels that may breakdown the seals leading to an earlier failure.
The invention is also directed to having an improved technique for passing piping and conduits into and through a sump wall and to retain integrity and alignment with a dispenser above the sump.
These objects and other objects of the invention are achieved by the invention in the manner set out below.
SUMMARY OF THE INVENTION
According to the invention, there is provided a sump for inhibiting leakage of liquid contained therein. There is a double wall for at least part of the sump. The sump defines a cavity for containing liquid. There is an interstitial space between the double wall. An indicator liquid is located in the space.
A sensor is in fluid communication with the interstitial space such that a change in the pressure or liquid level in the interstitial space causes the sensor to indicate leakage into or from the interstitial space.
Also according to the invention the sump includes a base, and a wall directed upwardly from the base of the sump towards the top, thereby forming a cavity for liquid.
An angular portion of the upwardly directed wall is directed at an angle from the base greater than 90 degrees and a remote location of that angular portion is connected with an upright wall to the sump.
According to the invention there is provided a system of dispenser containment utilizing a primary, namely an inner, and a secondary, namely an outer, wall. An interstitial space between the two walls traps an interstitial fluid to test the integrity of the dispenser containment and the fittings that pass through the walls.
Preferably a minimized quantity of fluid is located in the interstitial space. This is achieved by retaining the interstitial space as relatively small as possible. This makes the change in the liquid level in the space enhance changes in the level to find small leaks quickly.
In large dispenser sumps {fraction (1/10)} of a gallon change allows one to visually see a change of 1″ in the level of a manometer or electronic sensor associated in fluid connection with liquid in the interstitial space. The interstitial test fluid is permanently left inside the interstitial space thereby eliminating the need and cost to treat hazardous material cost and virtually eliminating the dispenser containment tests.
Preferably, a manometer is employed. The manometer can be used to identify the height at which a leak can occur. This reduces the time to trouble shoot. The manometer can be used to measure small volume changes either visually or through electronic float sensors. The visual inspections are perfor
Bravo Sergio M.
Mukai Don K.
Greenberg & Traurig, LLP
S. Bravo Systems, Inc.
Simpson, Esq. Samuel K.
Walton George L.
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