TEST SYSTEM SELECTION

Unlike most system of units, as for example that measurable or that dimensional, the loss control requires almost necessarily a machinery. The right test method selection depends generally on the following parameters:

• Admissible loss rate value
• Test type: loss location or loss measurement
• Specific list of the tested detail: dimensions, pressure and empty resistance limit, packaging materials, surface finishes etc...
• Utilization and test conditions
• Security and environment parameters

Some of the applicable methods are quoted in the following schedule:

Method	Gas	Test type	Sensitivity [ Pa m3/Sec]
Tracer gases and Spectrometer	Helium	Local./ Pass-No Pass	10-11 … 10-6
« In bell » compliance interception test	Air	Pass-No Pass	10-6
Loss pressure test	Air	Pass-No Pass	10-5
Volume flow rate or mass flow test	Air	Pass-No Pass	10-4
Visual inspection in water tank  and pressure air	Air	Visual	10-4

The Helium method is not tested, as it is not contemplated in our production. It is considered in fact that the system is placed at the height of the sensitivity and the equipment and management costs make it applicable only where it is really necessary, that is to say on the limits of components for refrigerant gases, microelectronics, pace-maker, etc. The immersion test is not mentioned here too, because it has none of the technical abilities, but for the fact that it can really find and identify the loss point.
The short sensitivity level according to the rule must, in fact, be interpreted as method impossibility to give a measurement, and that means a total uncertainty if applied on product line, and a high management cost due to the impossibility to be automated.