Flowserve 50165 Nordstrom Figure - Manual (Page 22)

Nordstrom Figure 50165 and 50169 Dynamic Balance Iron Plug Valve FCD NVENIM2006-00 – 09/05
22
Design Features
To better understand the Dynamic Balance plug valve, listed are the principal design features. Refer to
pages 34–37 for illustrations.
1. Stem Wrench operated stems have wrench flats which align the wrench handle with the flow
passage of the Plug, thus becoming an easily visible position indicator.
2. Stem Seals O-rings are used for stem sealing.
3. Plug Balancing Spring Designed to preload the plug to prevent vibration and thermal cycling
from wedging the plug into the body taper even when the valve is installed upside down.
4. Bottom Balancing Hole An integral part of the Dynamic Balance System. The balancing hole
maintains pressure equalization between the plug port and the bottom of the plug.
5. Balance Hole with Ball Check (not shown) Ensures that pressure above the plug is the same as
or greater than in the plug port.
6. Sealant injection Fitting Permits restoration of damaged seats for drop-tight shutoff.
7. Stem Weather Seal (Wrench operated only) Specially shaped and constructed to protect the
stem-to-body joint from hostile environments that can lead to corrosion.
8. tapered Plug individually matched to each body and lapped to achieve the best possible fit. The
sealant grooves in the plug match the sealant grooves in the body to form the Sealdport groove
system.
9. Plug adjustment Screw provides a means of properly positioning the plug into the body after
valve assembly. A hex-head bolt (or three-bolt cover plate) is provided to reduce the chance of
accidental turning of the Plug Adjustment Screw.
Valve Front Identification
This manual will periodically refer to the valve front. For clarification, the front of the valve will have
these things in common:
• Sealant Injection Fitting
• Handwheel (gear operated only)
note: Refer to the Technical Data section for a parts list and exploded view of a “typical” wrench oper-
ated Dynamic Balance Plug Valve.
Gearing
Simple or single reduction worm gearing is used on Dynamic Balance iron plug valves.
All gear mechanisms are enclosed in weatherproof housings and packed with gear grease.
A Position Indicator, mounted on the upper end of the gear segment, aligns with the plug port to provide
a visible means of plug port positioning in relation to the flow line of the valve.
During operation, all parts of the gearing have free movement.