Ceram valves use ceramic plates to seal against corrosion, dust, dirt, and sand in air lines. One dynamic and one static plate are made of extremely hard aluminum oxide and are ground. They are available in ISO sizes I to IV, with flows from 1.1 to 7.5 CV. ISO standard 5599-1 sub-bases feature 14- to 1-in. NPT or ISO G (BSPP) port options. They are rated for working pressure to150 psi (can be externally piloted for low pressure or vacuum applications) and operate with or without line lubrication.
Bosch Rexroth Corp., Pneumatics