VALVE DISC DISASSEMBLY FIGURES 4A-4E
WARNING: For all of the following repair procedures, the hydrant must be isolated or the system depressurized and drained
before removing the hydrant components. Failure to do so may cause pressure to be released resulting in severe injury or
CAUTION: Shut off the Water Main Supply Valve and release the internal pressure to the Hydrant by removing the lowest
Pumper Nozzle Cap (F28), and slightly open the outlet valve to allow any residual water to drain from the
hydrant. The hydrant is now ready for service.
VALVE DISC INSPECTION
Nozzle leaking from around the Valve Disc:
NOTE: The following steps may be required if the rubber surface of the Valve Disc is damaged. If the Valve Disc is not
damaged, inspect the hose or pumper nozzle for damaged sealing surfaces and replace if necessary.
the NOZZLE DISASSEMBLY and REASSEMBLY sections of this manual.
1. Remove Hose Nozzle Cap (F19), or Pumper Nozzle Cap (F28), and Hose Nozzle Cap Gasket (F115), or Pumper Nozzle
Cap Gasket (F120), using an AVK Hydrant Wrench or adjustable hydrant wrench. See Fig. “3A,3B&3F”, on page 9.
2. Using a drift punch, remove the Nozzle Retaining Screw (F114). See Fig. “3C”, on page 9.
3. Use the AVK Threaded Wet Barrel Nozzle Wrench to remove the Threaded Hose Nozzle (F116), or Threaded Pumper
Nozzle (F126), turning them in a counter clockwise direction.
4. Remove Threaded Hose Nozzle O-ring (F147), See Fig. 3D, or Threaded Pumper Nozzle O-ring (F131), See Fig. “3E”,
on page 9.
5. Using a 15/64” or (6mm) Allen wrench, remove the Dummy Nut Retaining Bolt (F113) and Dummy Nut (F112).
See Fig. “4A”
6. The Valve Stem (F134 for 2.5” Valve Stem), (F138 for 4”-4.5” Valve Stem) can now be unscrewed, (In the closing
direction.), from the Stem Nut (F110) and removed from the Nozzle Section (F101). See Figs. “4A &4B”.
7. At this time, it is recommended the Inner Stem Nut O-rings (F111) and the Nozzle O-rings (F25 for Pumper Nozzle O-ring)
and (F22 for Hose Nozzle O-ring) be replaced.
8. Use a 7/64” or (3mm) Allen wrench and remove the Stem Nut/Thrust Nut Retaining Screw (F114). The Valve Disc
(F133 , for 2.5″), or (F137, for 4″-4.5″), can be removed from the Thrust Nut (F135, for 2.5″) or (F139, for 4″-4.5″), by
unscrewing the valve disc from the thrust nut. See Fig. “4C”
9. Push the thrust nut towards the threads and remove the Thrust Collars, (F136 for 2.5″), or (F140 for 4″-4.5″). See Fig.
10. Remove the Thrust Nut (F135, for 2.5″) or (F139, for 4″-4.5″), from the Valve Stem (F134, for 2.5″), (F137, for 4″-4.5″).
See Fig. “4D”
11. Remove the Thrust Nut O-ring (F141, for 2.5″) or (F142 for 4″-4.5″) valve stems. See Fig. “4E”
VALVE DISC REASSEMBLY AFTER INSPECTION:
1. Replace the Thrust Nut O-ring, (F141, for 2.5″) or (F142 for 4″-4.5″) valve stems. These o-rings act as a brake, DO NOT
grease the o-rings. Wipe off any grease that may have gotten on the o-ring during assembly. The 4″-4.5″ Thrust Nut
O-ring is larger than the 2.5″ Thrust Nut O-ring.
2. Slide the thrust nut over the stem end that has the o-ring. The threads of the thrust nut need to point toward the short end
so the valve disc can be threaded on it. Push the thrust nut over the o-ring to make room for the thrust collars.
3. Grease the inside grooves of the Thrust Collar (F136 for 2.5″), or (F140 for 4″-4.5″) with a food grade grease that contains
no acetate or silicone. Install the Thrust Collar over the grooves of the stems. The 4″-4.5″ Thrust Collars are larger than
the 2.5″ Thrust Collars. Avoid getting grease on the o-ring. Wipe off grease that may have gotten on the o-ring.
4. Pull the thrust nut up over the collars until it stops.
5. Screw the valve disc and thrust nut together until hand tight. Then use the appropriate hand tools to tighten.
6. Apply a drop of thread-locker (Loctite #242 or equal), to the end of the Stem Nut/Thrust Nut Retaining Screw (F114), and
screw into the hole on the side of the valve disc and tighten with a 7/64” or (3mm) Allen wrench..
VALVE DISC REASSEMBLY AFTER INSPECTION: (continued):
Note: The disc should not spin freely on the stem. The o-ring should act as a brake.
CAUTION: The valve disc assemblies should be tight enough to prevent linear movement on the stem, but loose enough
that you can rotate the assembly on the stem by hand.
7. DO NOT grease the ACME threads of the stems. Put food grade grease, that contains no acetate or silicone, on the
inside threads of the Stem Nut (F110), then screw the stem/valve disc assembly into the Stem Nut.
8. Place a Dummy Nut (F112) onto the pentagon of stem and secure it with a Dummy Nut Retaining Bolt (F113) that has a
drop of thread-locker (Loctite #242 or equal), on it. Tighten the bolt with 15/64” or (6mm) Allen wrench.
9. Follow the steps in “NOZZLE REASSEMBLY AFTER INSPECTION”, on page 9 to re-install the Nozzle/Cap assembly.
NOTE: Hydrants manufactured between July, 1998 through May, 2006, with the older style multi piece Valve Disc/Stem
assembly can retrofitted with the new style Valve Disc/Stem assembly. Contact AVK Customer Service for