Leak tester
First Claim
1. In a leak tester having means for providing pressurized fluid into a chamber of a fluid receptor, means for isolating said chamber subsequent to provision of the fluid therein, and means for sensing the pressure of the fluid in said isolated receptor, the improvement comprising:
- means for sequentially determining the sensed pressure at at least four different times during a measuring period following the isolation of the chamber during which period the pressure in said isolated chamber changes exponentially due to a stabilization of the pressurized fluid therein toward a substantially constant value;
means for calculating from a first group of at least three successive pressure determinations a first end pressure to which the fluid pressure should stabilize and calculating from a second, subsequent group of at least three successive pressure determinations a second end pressure to which the fluid pressure should stabilize;
means for comparing said first and second calculated end pressures and determining a pressure differential therebetween;
means for determining a characteristic of the exponential curve defining the rate of the pressure drop due to the stabilization of the pressurized fluid; and
means for calculating the leak rate from the value of the determined characteristic and the determined pressure differential.
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Accused Products
Abstract
A method and apparatus for quickly determining leakage in pressurized fluid receptors. Pressure determinations are made substantially immediately following the completion of the filling of the item to be tested with the pressurized fluid without the need for a stabilization period. The complete decay curve is calculated from the pressure determinations. A time constant is determined from the curves defined when no leakage is present and is utilized in determining the leakage rate whenever the two curves defined by the pressure points provide different end pressure values. The determinations may be made by conventional microprocessor-based instrumentation to provide a substantial increase in the rate of conducting fluid leakage tests.
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Citations
16 Claims
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1. In a leak tester having means for providing pressurized fluid into a chamber of a fluid receptor, means for isolating said chamber subsequent to provision of the fluid therein, and means for sensing the pressure of the fluid in said isolated receptor, the improvement comprising:
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means for sequentially determining the sensed pressure at at least four different times during a measuring period following the isolation of the chamber during which period the pressure in said isolated chamber changes exponentially due to a stabilization of the pressurized fluid therein toward a substantially constant value; means for calculating from a first group of at least three successive pressure determinations a first end pressure to which the fluid pressure should stabilize and calculating from a second, subsequent group of at least three successive pressure determinations a second end pressure to which the fluid pressure should stabilize; means for comparing said first and second calculated end pressures and determining a pressure differential therebetween; means for determining a characteristic of the exponential curve defining the rate of the pressure drop due to the stabilization of the pressurized fluid; and means for calculating the leak rate from the value of the determined characteristic and the determined pressure differential. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. The method of testing fluid receptors for leaking comprising the steps of:
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providing pressurized fluid into a chamber of the fluid receptor; isolating said chamber subsequent to provision of the fluid thereinto; sensing the pressure of the fluid in said isolated receptor; sequentially determining the sensed pressure at at least four different times during a stabilization period following the isolation of the chamber during which period the pressure in said isolated chamber changes exponentially due to a stabilization of the pressurized fluid therein toward a substantially constant value; calculating from a first group of at least three successive pressure determinations a first end pressure to which the fluid pressure should change after infinite time and calculating from a second, subsequent group of at least three successive pressure determinations a second end pressure to which the fluid pressure should attain after infinite time; comparing said first and second calculated end pressures and determining a differential therebetween; determining a characteristic of the exponential curve defining the rate of the pressure change due to the stabilization of the pressurized fluid; and calculating the leak rate from the value of the determined characteristic and the determined pressure differential. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification