Abstract: An apparatus and procedure is provided for testing and evaluating the sealing effectiveness of dynamic seals of the type having at least one and often at least two dust-excluding seals. Included is a housing having a support wall formed with an opening through which a representative shaft is supported for rotation. An annular gap exists between the shaft and wall opening and is closed by the test seal. A dust chamber is provided on the atmosphere side of the test seal and includes a slow speed dust redistribution device which gathers and transports dust from the bottom of the chamber to the top where it is released and falls back into the chamber. A high speed beater agitation device disperses the released dust to maintain a constant density dust cloud environment within the dust chamber. A dry dust collection chamber is provided on the opposite oil side of the test seal.