(under subclass 411) Apparatus having means to cause a backwash liquid, usually filtrate, to traverse the filter medium as a pressure wave, i.e., having pressures varying between two or more peaks, e.g., pistons reciprocating within a cylindrical filter medium or an intermittently actuated pulsator.
SEE OR SEARCH THIS CLASS, SUBCLASS:
349, for a filter having pulsation dampeners or gas trapping means.
356, for a filter constructed to cause flexing of the medium by a fluid.
359, for a filter having mechanical means for flexing the medium.
384, and 388+, for a filter having vibrating means.
748, for processes involving pulsation or oscillation.
