Leak detection method and system for product lines in fuel dispensing systems
AssigneeMarley Pump
InventorsLarry E. Seitter, Jerry W. Bradshaw
Life of this patent
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Abstract
A leak detection system which operates at relatively high pressures and senses relatively large pressure drops to monitor for leakage in fuel product lines such as those used for dispensing of fuel at gasoline service stations. Leakage tests of various degrees of precision are carried out, and the possible effects of thermally induced expansion and contraction are taken into account. The system also checks for faulty pressure sensors and dry tank conditions. Leak indications are confirmed by a time delay and retesting before a leak alarm is given.
Claims10
In a leak detection apparatus for a fuel product line through which fuel is pumped by a pump for dispensing, the improvement comprising:
- means for sensing a preselected pressure in the product line that is approximately 15 psi below a relief pressure at which the product line is normally maintained when fuel is not being pumped therethrough;
- means for declaring a passed hourly test if said preselected pressure in the product line is not sensed within a first time duration;
- means for declaring a passed monthly test if said preselected pressure in the product line is not sensed within a second time duration longer than said first duration;
- means for declaring a passed annual test if said preselected pressure in the product line is not sensed within a third time duration longer than said second duration;
- means for sensing the presence of thermally induced expansion in the product line;
- means for overriding all of said declaring means and effecting a thermal expansion test mode when thermally induced expansion is present;
- means when in the thermal expansion test mode for declaring a passed monthly test if a predetermined pressure higher than said preselected pressure but below the relief pressure is not sensed within a fourth time duration longer than said second duration;
- and
- means when in the thermal expansion mode for declaring a passed annual test if a predetermined pressure higher than said preselected pressure but below the relief pressure is not sensed within a fifth time duration longer than said third duration.
In a pressure decay leak detection system for a fuel product line of the type that normally detects absence of leakage based on a preselected pressure drop in the product line not occurring during a predetermined time period, the improvement comprising:
- means for sensing the presence of thermally induced expansion in the product line;
- and
- means, operative when thermally induced expansion is present in the product line, for declaring the absence of leakage if a selected pressure drop in the product line less than said preselected pressure drop does not occur during a selected time period greater than said predetermined time period.
Dependencies are inferred from the claim text.