Bell & Gossett HS 114B Model 78 Water Main Vent Valve Internal Parts Kit Part No. 601402 - Manual (Page 2)

Old Design Internal Parts Kit (P.N. 601402) contains O-
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.
1/32-INCH CHAMFER
UNDERCUT
AREA
AT BOTTOM
OF THREADS
Cap
Diagram A Diagram B
Base
New Design
3/32-INCH CHAMFER
NO UNDERCUT
Cap
Diagram C Diagram D
Base
HS-114 8/18/00 11:49 AM Page 2