... hollow ball, etc. The Water Treatment Media (Plastic Random Rings), with big specific surface, big free volume, are very ... the following series of plastic random packings: 1. Plastic Random Rings (Materials: PP, PVC, CPVC, etc.)a. Pall Ringb. ... CPVC and PVDF.2) Main types: pall rings, polyhedral hollow balls, conjugate rings, teller rosetterings, cascade rings, saddles, VSP, helix rings, hollow balls.3 ...