Apparatus for packaging a pourable product, comprising: - a first housing delimiting therein an isolation chamber configured to contain an atmosphere controlled in a sterile and/or aseptic condition; - a filling machine for filling containers with said pourable product, said machine being housed in the isolation chamber; and - a fluidic circuit comprising a main conduit or duct configured to feed a working fluid into the isolation chamber; wherein the apparatus further comprises a second housing delimiting therein a test chamber, said test chamber being operatively separated from the isolation chamber and configured to contain an atmosphere controlled in sterile and/or aseptic condition; wherein the isolation chamber is external with respect to the test chamber; and wherein the fluidic circuit comprises a branch extending from the main duct to the test chamber for conveying the working fluid therein and allowing a sampling of the working fluid inside the test chamber; wherein the isolation chamber defines a sterile and/or aseptic production area, the filling machine being arranged in the production area; wherein the test chamber defines a test area for the working fluid, said test area being sterile and/or aseptic and operatively separated from the production area, the production area being external to the test area; and wherein the branch is configured to convey the working fluid to the test area, for allowing a sampling of the working fluid inside the test area and externally relative to the production area; characterized in that the branch comprises a terminal arranged in the test area and configured to receive in coupling a test device, for the sampling of the working fluid inside the test area and externally relative to the production area. - a first housing delimiting therein an isolation chamber configured to contain an atmosphere controlled in a sterile and/or aseptic condition; - a filling machine for filling containers with said pourable product, said machine being housed in the isolation chamber; and - a fluidic circuit comprising a main conduit or duct configured to feed a working fluid into the isolation chamber; wherein the apparatus further comprises a second housing delimiting therein a test chamber, said test chamber being operatively separated from the isolation chamber and configured to contain an atmosphere controlled in sterile and/or aseptic condition; wherein the isolation chamber is external with respect to the test chamber; and wherein the fluidic circuit comprises a branch extending from the main duct to the test chamber for conveying the working fluid therein and allowing a sampling of the working fluid inside the test chamber; wherein the isolation chamber defines a sterile and/or aseptic production area, the filling machine being arranged in the production area; wherein the test chamber defines a test area for the working fluid, said test area being sterile and/or aseptic and operatively separated from the production area, the production area being external to the test area; and wherein the branch is configured to convey the working fluid to the test area, for allowing a sampling of the working fluid inside the test area and externally relative to the production area; characterized in that the branch comprises a terminal arranged in the test area and configured to receive in coupling a test device, for the sampling of the working fluid inside the test area and externally relative to the production area.