in various embodiments a fluid control device suitable for high pressure analytical instruments includes a housing having an interior surface with an end wall . the interior surface defines a chamber . a valve assembly disposed in the chamber controls the flow of fluid through the chamber . an end cap is disposed in the housing opposite the end wall to enclose the chamber . the end wall and end cap each have an opening to pass a fluid to the chamber or to remove a fluid from the chamber . the housing and end cap each has an abutment surface to receive the other abutment surface . at least one of the abutment surfaces has a plastic seal coating . a means of compression , such as a compression housing and compression sleeve , is included to engage the end cap to deform the plastic seal coating between the abutment surfaces and thereby seal the chamber .