Xylem Bell & Gossett Hoffman Specialty 78 Manual

HS-114D
511094
Hoffman Specialty
®
Model 78
Internal Parts Kit - Part No. 601402
Internal Parts Kit (P.N. 601402) contains O- Old rings for both
the old and new design of the Model 78 Water Main Vent
Valve. It is important that the proper O-ring be installed into
the correct base.
The larger diameter and cross section O-ring is for use
with the old design Vent Valve. Improper sealing and
leakage will occur if the smaller O-ring is used with the old
design Vent Valve. This may result in property damage or
personal injury. The old design Vent Valve can be identified
by examining the outside thread area of the cap, or the inside
thread area of the base.
The old design cap has only a small chamfer (approximately
1/32") on the outside edge of the cap. Refer to the cross
section Diagram A. The old design has an undercut at the
bottom of the internal threads. Refer to the cross section
Diagram B.
For reference, Diagrams C and D show cross section views
of the new design cap and base.