Valve Seals are used to minimize process fluid leakage along the stem that connects the internal parts with the external actuator. These seals leak to minimize product release and maintain valve seals in good condition. The valve seals are usually made of neoprene. Valve seals are used to limit the amount of oil that is used to lubricate the valve stem and valve guide. Valve seals keep oil from draining down through the space between the valve stem and the valve guide. Valve seals for the intake and exhaust valves are commonly of different designs & materials. These valve seals are replaced without removing the cylinder head. There are three basic designs of valve seals such as positive lock, umbrella type and simple o-ring seals.