Air-Loaded, Globe Trim, ANSI IV or VI The Mark 686G features air-loading, high capacities, accurate regulation, and easy servicing, making it an exceptional choice for your pressure regulating applications. The Mark 686G has a large effective diaphragm area for increased accuracy and sensitivity along with large orifices and body passages which provides high flow capacities. Easily removable bottom cap of this air loaded pressure regulator allows quick access for replacing seat and plug.