DIN 6663
DIN 6663 Pneumatic tube systems - Workmanship of components for pneumatic tube systems in plastics (PVC-U), ferrous steel and stainless steel
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 06/01/1999
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 06/01/1999