Integrity test for a double filter capsule

A system for conducting an integrity test, comprising:

• a double filter capsule with a housing in which a first filter and a second filter are arranged one after the other in the flow direction of a medium to be filtered such that in a filtration process the medium to be filtered flows in its flow direction from an antechamber in the housing through the first filter into an interspace between the first filter and the second filter and onward through the second filter to an outlet, the housing having an antechamber access for supplying a test fluid into the antechamber and an interspace access for supplying the test fluid into the interspace;
• a connecting line between the antechamber access and the interspace access for fluidic connection between the antechamber and the interspace, wherein at least the fluidic connection to the interspace is configured to close;
• and
• an integrity check device designed to conduct the following two test phases and, based thereon, to determine an integrity state of the double filter capsule:
• a first test phase, comprising:
• supplying the test fluid into the antechamber with the fluidic connection of the connecting line to the interspace closed and carrying out a first integrity check;
• and
• a second test phase, comprising:
• simultaneously supplying the test fluid into the antechamber and via the interspace access into the interspace, while the antechamber is fluidically connected to the interspace via the connecting line such that pressure equalization takes place between the antechamber and the interspace, and carrying out a second integrity check.