... specific surface, Big free volume, Pall Ring, hollow ball, etc. The Water Treatment Media (Plastic Random Rings), with big specific surface ... good filter media for kinds of water treatment. The PP Pall Ring and the Hollow Balls are popular. Now, we have ... in mediums: 60 - 150°C 5) Widely used in the packing towers in petrochemical, chemical, chloro-alkali, gasand environmental protection industry6) ...