Some confusion exists about which style of gasket to use. The full face gasket with eight bolt holes should only be used with raised flange units. All units have been built with raised face head flange since January of 1996. Since all replacement heads are now sold with a raised flange, the 8 bolt gasket can be used with any control.

The round donut shaped gasket should be used on the flat flange units. The gasket fits inside the bolt hole circle, which is the area where the most compression of the gasket occurs. Using the eight bolt hole gasket on flat face flanges compromises the sealing integrity of the gasket which could lead to leakage.

Whether a flat or raised flange, the flange surface should be cleaned completely prior to installation. The gaskets are not designed to make up for any material left in place from old gaskets. The flange surfaces should also be inspected for nicks and burrs. If any are present, the unit should be replaced.