Apparatus and method for automatic leak detection

An apparatus for automatic leak detection, comprising:

• a chamber to enclose a test specimen, the test specimen having a pressurizable volume that is pressurizable when leaks are smaller than a predetermined threshold;
• a vacuum pump in selectable fluid communication with the chamber;
• an adiabatic noise cancellation valve to selectably open and close the selectable fluid communication between the vacuum pump and the chamber;
• a differential pressure transducer connected to the test specimen and a reference volume for directly determining a pressure difference between a pressure in the test specimen and an other pressure in the reference volume, and for transmitting a signal indicative of the pressure difference to a controller, wherein:
• the apparatus is configured to operate when the test specimen is at least 5 degrees Fahrenheit warmer than the reference volume;
• and
• the reference volume is located:
• outside of the chamber and the reference volume is at ambient temperature, or
• within the chamber and the reference volume is at a chamber temperature;
• and
• the controller to control the adiabatic noise cancellation valve to cause the vacuum pump to draw a vacuum from a space between the test specimen and the chamber thereby creating an adiabatic noise cancelling condition in which a temperature of the test specimen is stabilized, an electronic pressure switch and electronically controlled valve to control a flow of a test gas through parallel ports of the electronically controlled valve into the test specimen and into the reference volume to reach a predetermined test pressure;
• the controller to determine a pressure decay rate from the signal indicative of the pressure difference;
• the controller to determine if the test specimen meets a leak test specification based on the pressure decay rate under the adiabatic noise cancelling condition.