A number of industries such as suppliers of automotive parts (e.g. engine blocks, air bags, etc.), medical equipment (e.g. catheters) and food packaging rely on various verification tests to ensure that critical parts are leak proof.
In general, there are two ways to measure flow. Either a mass flow meter can be used directly to measure the mass flow of gas (typically industrial air or helium) escaping due to a leak. Or the measurement can be conducted indirectly by measuring the drop of pressure (pressure decay testing) after having filled the tested item. Since leak testing is usually part of the standard quality assurance process in production, quick leak testing cycles are essential. A mass flow meter that possesses a quick reaction time delivers the required efficiency. Additionally, the system or unit being tested needs to reach gas equilibrium (stable conditions) before a reliable leak test can be undertaken. For a quick determination of the stable state, flow measurement in both directions is required.