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CONTROL VALVES 762, 763, 765, 766 AND 767
10
Corrective maintenance
Topics covered in this chapter:
•
Control valve troubleshooting
•
Verify the return to operational condition
10.1
Control valve troubleshooting
Use the table below to troubleshoot the control valve. Contact the nearest Flow Lifecycle
Services center for assistance with repairs of Daniel products. It is important that servicing
be performed by trained and qualified service personnel.
Troubleshooting issues for 765 Control Valves
Table 10-1:
Condition
Probable cause
Correction
(1)
Valve will not open
Upstream valve is
closed
Open upstream valve.
Pump is not operating
Start pump and check for cavitation.
Downstream valve is
closed
Open downstream valve. (Check coupler on bot-
tom loading units and internal valve in truck.)
Insufficient pressure
Check pump. Check bypass and strainer located
in line.
Swollen O-rings
Disassemble valve and replace O-rings. Check
compatibility of O-rings with product.
Valve opens too slowly Valve inlet pressure be-
low normal
Check strainer and pump for obstruction.
Swollen O-rings
Disassemble valve and replace O-rings. Check
compatibility of O-rings with product.
Valve will not close off
tightly
Foreign material in
main valve piston seat
Disassemble valve and inspect piston.
Swollen O-rings
Disassemble valve and replace O-rings. Check
compatibility of O-rings with product.
Piston or seat O-ring
cut or defective
Disassemble valve and replace if necessary.
(1) Refer to
Mechanical disassembly
procedures.
10.2
Verify the return to operational condition
Once corrective maintenance has taken place, verify that the control valve is working
properly by following the steps below.
Corrective maintenance
User manual
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