Abstract: The invention relates to the destruction of foams that are produced in various industrial processes, especially in the degassing and/or removal of monomers from plastics dispersions, by the use of porous filter elements without using moving mechanical foam-destroying devices and/or without the addition of chemical foam-destroying agents.

Abstract: This invention relates to a valve for the introduction of a gas into a liquid media comprising a housing, said housing having an exit port at one end, and exit port at the opposite end and a gas entrance port, said housing containing a movable hollow piston in a substantially water-tight connection with said housing, said movable hollow piston being sealed at each end and having gas distribution jets at one end, and a gas entrance port in communication with said housing gas entrance port when said hollow piston is extended, said hollow piston being in a substantially gas-tight connection with said housing when retracted, and means for extending and retracting said movable hollow piston in said housing, whereby when said hollow piston is extended, said gas distribution jets are exposed beyond said housing and a gas path is created from said gas entrance port to and through said gas distribution jets.