Development, developmental testing and practical application of high-sensitivity tests for total leak rate of pressurized compartments and fluidic subsystems of large scale space vehicles without the use of vacuum chambers

The paper discusses the results of many years of development, developmental testing and practical application of highly-sensitive tests for total leakage without the use of vacuum chambers on pressurized compartments and fluidic subsystems of large scale space vehicles, taking as an example the Russian Docking Compartment DC (1995) and Mini Research Module MRM-1 (2010), Russian systems and the pressurized compartment of the five European Automatic Transfer Vehicle ATV (2005-2014) during ground pre-flight processing at launch sites. The tests are conducted in accordance with an improved accumulation method at atmospheric pressure using Helium as the tracer gas. The minimal detectable leak rate of 100% helium can be as low as 3,27-10-2 mTorr-L/s at air absolute atmospheric pressure in the 100 m3 accumulation volume and one hour of exposure time. The use of helium leak detectors with turbomolecular pumps and procedures improved on the base of test results makes it possible to develop test processes that in certain cases can replace the conventional process of testing of assembled space vehicles and modules in large vacuum chambers if the ones are not available at the launch sites.