Abstract: The preferred form of the present invention is directed to systems and methods used to test objects including but not limited to filters, respirator cartridges and filter media. The object to be tested is subjected to an aerosol challenge while the penetration percentage and resistance at a given flow are monitored to ensure that the object will function as desired. Preferably, the test object is challenged with a salt aerosol. However, any suitable aerosol may be used. A replenishment member is provided for automatically and continuously replenishing the reservoir of an aerosol generator. The replenishment member is configured such that there is no need for an operator to monitor the liquid level in the aerosol generator reservoir either during replenishment or at anytime while the apparatus is operated. The replenishment member of the preferred form of the present invention does not require interruption of the filter testing process to replenish the aerosol generator reservoir.