A vial washing machine is an automated device used in pharmaceutical and biotech industries to clean vials before they are filled. These machines use a sequence of washes with various media, such as water for injection (WFI), purified water, and compressed air, to remove contaminants and ensure sterility. They are available in both rotary and linear designs, can handle different vial sizes, and often comply with cGMP standards to guarantee a sterile and hygienic environment for packaging products like vaccines and injectables.