Rotary seals by CinchSeal are purged with air, or silicone grease if air isn’t available. If grease is used, the customer must apply enough grease to fill the whole cavity until you start to see grease leaking out of the Teflon® faces. We prefer the customer to use air, but understand it isn’t always an option. When you use air purge seals, there are 3 major things to remember:
1) When the air is piped from existing plant air directly into the seal, it creates pressure to push the rotor against the stator and closes the sliding interface to stop any material from going into or out of the screw conveyor.
2) We tell people to set their air gauges 5 to 7 psi higher than the vessel pressure, so that we have a higher pressure inside the seal than outside of it, creating an air barrier to keep product out of the seal.
3) The air keeps the rotating seal faces cooler by reducing heat caused by friction. This helps prolong the life of the seal as well. From our experience, customers usually get 1 to 2 times longer life out of their seals when they use air.