Leak tester and leak testing method

A leak testing method for testing the tightness and outward leakage of a test object provided with a first opening and a second opening and having an internal volume between said first and second openings, where no fluid is allowed to flow from said first opening to said second opening for the case of the non-leaking test object, comprising:

• feeding a fluid of a predetermined pressure to said test object through said first opening;
• feeding said fluid of said predetermined pressure to a master, said master having substantially the same internal volume as said test object;
• measuring a pressure difference between a pressure of said fluid within said test object and that within said master;
• and
• measuring a flow rate of said fluid flowing out of said test object only through said second opening to detect an internal leakage inside the test object,
• wherein said method detects an outward leakage of said fluid from said test object other than that internal leakage through said second opening on a basis of said measured pressure difference and said measured flow rate.

A leak tester for detecting outward leakage other than an internal leakage of a test object having a first opening, a second opening, and a first internal volume provided between the first and second openings, the first internal volume having at least one restrictor therein which restricts a fluid flow from the first opening to the second opening, where no fluid is allowed to flow from said first opening to said second opening for the case of the non-leaking test object, comprising:

• a master having a second internal volume;
• a pressure source which provides pressurized fluid to the test object through the first opening and to said master;
• a first measuring unit which measures a difference between a pressure inside the test object at an upstream side of the restrictor and a pressure inside said master;
• and
• a second measuring unit which measures an amount of said fluid leaking through the restrictor,
• wherein the leak tester detects the outward leakage through the restrictor based on said measured pressure difference and said measured fluid amount.