A daily contact lens manufacturer have been using AKO stainless steel flanged PN10/16 Pinch Valves within their application for 10 years. The pinch valves have a white food quality natural rubber sleeve inside, and are on a regrind system which was installed by an installation company.
The pinch valves are used in conjunction with a system for reclaiming reground plastic moulds to be used for packaging blisters. The pinch valves for contact lens manufacture are passing regrind material, and the temperature is around room temprature. The regrind is not under pressure but sits in a compartment of the grinder until vacuumed away to the system.
The pinch valves are on the pipework just after the grinders and the food quality natural rubber sleeves (product code M050.02X) are held in the closed position by around 4 bar of air via solenoid valve, until required to be opened to convey the regrind. This process occurs for 10 seconds every 5 minutes, for 5 days a week.
The company have 6 valves for contact lens manufacture which open one after the other during a cycle. The amount of vacuum is not known but it is made by a 3 phase 4kwatt vacuum pump connected to the system pipework.
The plant engineer on site told us that they are satisfied with the AKO pinch valves and only have to change the internal sleeves (also known as bladders, diaphragms, tubes, hoses, membranes) on occasion around 2 or 3 per year on the 6 units that they have installed.