Test modes and typical applications
|Test mode||Typical application|
|Pressure decay||Leak tightness of test parts|
|Pressure rise||Leak tightness of combined chambers|
|Dynamic pressure||Continuity test|
|Pressure steps||Opening point of valves|
|Closed component||Leak tightness of sealed test parts|
|Volume measurement||Determination of test part volumes|
|Mass flow||Leak tightness of test parts with large volume and small rates|
|Flow||Flow though pipes|
Overview test data and test ranges
|Test pressure||-1 bar ... 300 bar|
|Measurement range||400 Pa ... 30.000 Pa|
|Test part volume||0,1 ml ... 10.000 ml|
|Leak rate||0,6 ml/min ... 10 ml/min|
|Total test time||1 s ... 100 s (depending on test part volume)|
- Testing for oil-tightness or watertightness
- Leak testing according the requirements of the IP protection classes
- Testing of enclosures (e.g. gear box cover, reservoires, shiners)
- Testing of coolers, gear boxes (inner and outer leak tightness)
- Leak testing of parts with venting elements (e.g. membranes)
- Testing of sensors, clocks, micro electronic devices (closed components)
- Testing of elements with hydraulics (e.g. shock absorbers, servo pumps)
- Continuity test of pipes and valves
- Determination of the opening and closing point of valves
- Flow test of pipes, valves, membranes, exhaust-gas sysytems
Influence of height on air pressure - Barometric height formula
In case of leak tests using negative overpressure, vacuum pumps are normally used for producing negative overpressure. At sea level, it is usually unproblematic to reach the desired negative overpressure in the test part. However, the situation is quite different if the production line and test stand are located in altitude. With the decrease of air pressure due to height, it can happen that the evacuation of the test part to reach the target pressure is not possible any more. The height-dependant decrease of air pressure is quantified by the so-called „barometric height formula“.
For heights up to approx. 100 km, we have:
with p0 = 101.325 Pa (air pressure at sea level at 0°C) h = altitude in m
In the vicinity of the earth surface, we have approximately: For each 8 m gained or lost in altitude, the air pressure decreases or increases by 100 Pa, equivalent to 1 mbar.
Conclusion: In case of leak tests with negative overpressure, the appropriate height-dependant air pressure must be taken into account when choosing the parameters of the test.
Complementary remark: For very accurate calculation of air pressure, please observe that the air temperature decreases with the altitude. This relationship is also quantifiable.