초록 ▼

A microprocessor is employed to control a test program which operates to cause a component under test to be filled (or evacuated) to a predetermined pressure P2 at which a leak test is to be carried out. The test program is arranged firstly to perform a rapid test at atmospheric pressure P1 to deter

A microprocessor is employed to control a test program which operates to cause a component under test to be filled (or evacuated) to a predetermined pressure P2 at which a leak test is to be carried out. The test program is arranged firstly to perform a rapid test at atmospheric pressure P1 to determine the pressure change dpl′/dt in the component due to the temperature fluctuation. The component is then filled (or evacuated) automatically to the test pressure PT, at which the leak check is carried out. Temperature compensation is achieved by subtracting the value of C dpl′/dt from the pressure change dpt/dt actually measured, i.e. the actual leak rate dPL/dt is given by [Figure] where the constant, C, is generated from an identical proram run, the calibration run, on a known non-leaker with a high temperature fluctuation.

대표청구항 ▼

A method for accurately determining the actual leak rate from a test vessel of unknown leaking characteristics, said method comprising the steps of: providing a calibration vessel known to be substantially free of leaks; filling the calibration vessel with air to prevailing atmospheric pressure, P1;

A method for accurately determining the actual leak rate from a test vessel of unknown leaking characteristics, said method comprising the steps of: providing a calibration vessel known to be substantially free of leaks; filling the calibration vessel with air to prevailing atmospheric pressure, P1; altering the temperature in the calibration vessel from ambient temperature; sealing the calibration vessel; generating and storing a signal corresponding to the rate of change of pressure in the calibration vessel to determine dP1/dt; altering the volume of air in the calibration vessel to achieve a test pressure P2, which is different from P1; sealing the calibration vessel; generating and storing a signal corresponding to the rate of change of pressure in the calibration vessel to determine (dP2/dt); computing a ratio, C, of (dP2/dt) divided by (dP1/dt); filling the test vessel with air to prevailing atmospheric pressure P1; sealing the test vessel; generating and storing a signal corresponding to the rate of change of pressure in the test vessel to determine (dP1/dt)′; altering the volume of air in the test vessel to achieve the test pressure PT; generating and storing a signal corresponding to the rate of change of pressure in the test vessel to determine (dPT/dt); and generating a signal corresponding to the actual leak rate from the test vessel by subtracting from the measured rate of pressure change (dPT/dt) the product of the ratio C multiplied by the measured rate of pressure change (dP1/dt)′.