Submittal Sheet

Page 3 of 8
WILKINS a Zurn company, 1747 Commerce Way, Paso Robles, CA 93446 Phone:[phone] Fax:[phone]
IN CANADA: ZURN INDUSTRIES LIMITED, 3544 Nashua Dr., Mississauga, Ontario L4V 1L2 Phone:[phone] Fax:[phone]
Product Support Help Line: 877-BACKFLOW (877-222-5356) • Website: http://www.zurn.com
All WILKINS Model 48 Gate Valves must be inspected and maintained by qualied, licensed personnel at least once a
year or more frequently as specied by local codes. Replacement of worn or damaged parts must only be made with
genuine “WILKINS” parts.
Servicing Wedge and Bonnet Seal:
1. Shut off main water supply. If servicing a gate valve attached to the downstream side of a
backow preventer, the upstream shut-off valve may be closed instead of the main water supply.
2. Relieve line pressure.
3. Remove bonnet nuts and bolts.
4. Slowly lift and remove bonnet assembly and wedge from valve body.
5. Clean all parts thoroughly after disassembly.
6. Carefully inspect bonnet seal and wedge for wear or damage. Replace if worn or damaged.
7. Carefully inspect body interior seating surface for coating damage and foreign debris.
Clean seating surface or replace valve if necessary.
8. Reinstall wedge and bonnet assembly.
9. Tighten down bonnet nuts and bolts evenly. Do not over tighten.
Servicing Gland Stufng Box (OS&Y):
1. Make sure gate valve is fully open.
2. Remove gland nuts.
3. Raise gland and gland bushing.
4. Remove packing rings from stufng box using a small pick or similar device.
5. Replace worn or damaged packing rings.
6. Lower gland and gland bushing and lightly tighten gland nuts.
7. Cycle valve fully closed to fully open.
8. If there is stem leakage, tighten gland nuts until leakage stops.
Servicing Stem Seals (NRS):
1. Shut off main water supply and relieve line pressure.
2. Remove the bolt and washer retaining the operating nut/handwheel.
3. Remove operating nut/handwheel.
4. Remove gland ange bolts and gland ange.
5. Remove stem by turning stem clockwise.
6. Replace stem o-rings, gland ange o-ring, wiper ring, and thrust washers if necessary.
7. Reassemble in reverse order.
PROBLEM
1. Body Leakage
2. Seat Leakage
3. Stem Leakage
POSSIBLE CAUSES
1. Loose bonnet bolts
2. Dirty or damaged bonnet seal
1. Foreign debris caught in seat
2. Dirty/corroded seat
3. Damaged seat
1. Packing nuts loose
2. Stem o-rings worn (NRS)
3. Packing rings worn (OS&Y)
CORRECTIVE ACTION
1. Tighten bolts
2. Inspect bonnet seal. Clean or
replace if necessary
1. Cycle valve and ush line
2. Flush line or disassemble and clean
3. Repair or replace valve
1. Tighten nuts
2. Replace stem o-rings
3. Replace packing rings
Troubleshooting
Maintenance Instructions