Emerson Daniel 762, User Manual

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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 Section 9.3 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
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