Instructions / Assembly

PROBLEM POSSIBLE CAUSES CORRECTIVE ACTION
1. Main Valve fails to close 1. No pressure at valve Inlet 1. Check Inlet pressure
2. Main valve diaphragm ruptured 2. Disassemble, clean, and replace defective parts
3. Pilot Valve not closing 3. See pilot system troubleshooting
4. "Wye" Strainer plugged 4. Remove, clean, and/or replace
5. Ball valves closed 5. Open ball valves
6. Foreign matter between disc and seat or worn disc 6. Disassemble the main valve, remove debris, clean parts, and
replaced defective parts
2. Main Valve fails to open 1. Scale on stem or diaphragm assembly inoperative 1. Clean parts, and replace defective parts
2. Ball valves closed 2. Open ball valves
3. Pilot Valve fails to open 3. See pilot system troubleshooting
4. Obstruction in cover 4. Disassemble and remove obstruction
5. Worn stem o-rings 5. Remove and replace as needed
DIAGNOSIS CHECKS
CAUTION: Do not service valve while under pressure. Performing
diagnosis checks on the ZW205 when the valve is fully open, high
ow rates and high downstream pressures can occur. In order to
prevent harm to personnel, equipment, and downstream piping be
sure that there are no blocked valves in the system before perform-
ing checks.
DIAPHRAGM CHECK
1. Slowly close upstream shut off valve and relieve all pres-
sure downstream.
2. With all pressure relieved in the main valve, close both
upstream and downstream pilot ball valves. Remove side plug
on cover and leave off.
Troubleshooting
PROBLEM POSSIBLE CAUSES CORRECTIVE ACTION
1. Pilot Valve not opening 1. Over compressed spring 1. Loosen adjusting screw
(relief pressure too high) 2. Small pilot sense line clogged 2. Disassemble and clean or replace
3. Closed isolation ball valve 3. Open isolation ball valve
4. Worn diaphragm or stem o-ring 4. Disassemble and replace diaphragm or o-ring
2. "Wye" Strainer plugged 1. Clogged with debris or mineral deposits 1. Disassemble and remove obstruction
3. Pilot Valve not closing 1. Insufcient spring compression 1. Tighten adjusting screw
(relief pressure too low) 2. Damaged spring 2. Disassemble and replace parts as necessary
3. Worn seat seal or seat 3. Disassemble and replace seat seal or seat
4. Obstruction on seat 4. Disassemble and remove obstruction
5. Obstruction around diaphragm 5. Disassemble and remove obstruction
6. Worn seat o-ring 6. Disassemble and replace as needed
TABLE 2. MAIN VALVE TROUBLESHOOTING
When performing troubleshooting and diagnosis checks it is recommended that the following steps be performed in sequential order
for best results.
TABLE 1. PILOT SYSTEM TROUBLESHOOTING
The following troubleshooting information deals strictly with the
ZW205 valve and pilot systems. It is recommended to verify that
the pilot system is properly functioning before troubleshooting the
main valve. All troubleshooting can be performed without remov-
ing the cover. It is also recommended to permanently install a
model ZPI valve position indicator.
PILOT SYSTEM FUNCTION CHECK
CAUTION: To prevent personnel injury and damage to equipment
check that downstream venting is adequate prior to start-up and
test procedures.
1. Turn the pilot adjustment screw clockwise all the way in.
2. Close the downstream pilot ball valve. If installed, verify the
valve position indicator (model ZPI) is closed.
3. If there is continuous ow, the main valve is not sealing
properly. It is recommended that the main valve be disassembled
and inspected (Refer to “Disassembly” section).
4. Open the downstream pilot ball valve. If there was no ow dur-
ing the previous step, but there is now continuous ow, the pilot
valve is not sealing properly. It is recommended that the pilot
valve be disassembled and inspected.
5. Turn the adjustment screw counter-clock wise until water
starts to ow. If no water starts to ow and there is inlet pressure,
then the pilot is not functioning correctly. It is recommended that
the pilot valve be disassembled and inspected.
7. If the main valve and pilot valve are working properly refer
to Start-Up procedures to reset the desired relief pressure and
proceed with diagnosis checks for the main valve.
3. Then open upstream shut off valve partially, allowing water to
ow through the valve. While owing water monitor the opening
on the cover. Water will ow from the cover as the plunger as-
sembly rises, if water continues to ow once fully open then there
is most likely damage to the diaphragm or uid is leaking past the
diaphragm assembly due to loose assembly. It is recommended
that the valve cover be removed to investigate the leakage (To
remove cover see “Maintenance” section for procedures). If
water stops owing out of cover then the diaphragm is good and
you may proceed to the diaphragm movement check.
Note: At the beginning of this check a small amount of
water coming out of the cover is normal.
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ZURN WILKINS
1747 Commerce Way, Paso Robles, CA 93446 Phone:[phone] Fax:[phone]
www.zurn.com
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