Abstract: The present invention is embodied in apparatus for the automatic periodic sampling of kinetic fluids wherein means are provided for tapping a conduit in which fluid is flowing to divert the samples of the fluid into a sampling plenum where each sample is accumulated under pressure and thereafter discharged into a collection vessel in which several samples may be accumulated under pressure for eventual testing. The invention contemplates the maintenance of each sample under pressure and isolated from foreign environments including ambient air, electrical discharge and the like, and further provides for a failure sensing means capable for detecting system failure and automatically shutting down the system and optionally signalling the failure so that immediate repairs can be effected, thereby minimizing downtime.