A pressure sensor includes an antenna member that is adapted to be resonantly responsive to a desired frequency of electromagnetic radiation. A front-side secondary polygon is selected from the secondary polygons and drawn in a blackish color by rendering and hidden surface removal utilizing Z-buffering. , hydrocarbon solvent, in which the plant comprises means for separating solvent from the polymer including a flash tank and a vacuum devolatilizer. Additionally, when the net filter is mounted at the filter cover, the filter unit becomes modularized to be facilitate a detachable mounting.