Atlas Copco ZR350 VSD Oil-Free Rotary Screw Air Compressor — ISO 8573-1 Class 0 The Atlas Copco genuine ZR series variable speed drive (VSD) rotary screw compressor delivers certified 100% oil-free compressed air for demanding, high-capacity industrial production facilities. Certified compliant with ISO 8573-1 Class 0, the water-cooled ZR platform completely eliminates oil contamination risks in precision electronics fabrication, chemical processing, and automotive coating