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MODEL 700 CONTROL VALVE
10
10.1
Corrective maintenance
Control valve troubleshooting
Use the table below to troubleshoot the control valve. Contact the nearest
Daniel
Flow
services center for assistance with repairs of Daniel products. It is important that servicing
be performed by trained and qualified service personnel.
Table 10-1: Troubleshooting issues of model 700 Control Valve
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
bottom loading units and internal valve in
truck.)
Insufficient pressure
Check pump. Check bypass and strainer located
in line.
Clogged strainer
Clean strainer.
Swollen O-rings
Disassemble valve and replace O-rings. Check
compatibility of O-rings with product.
Valve opens too slowly Valve inlet pressure
below normal
Check strainer and pump for obstruction.
Swollen O-rings
Disassemble valve and replace O-rings. Check
compatibility of O-rings with product.
Check "X" port
sensitivity control
needle valve position
(maybe closed too
much)
Open sensitivity control needle valve.
Valve will not close off
tightly
Bent indicator stem
Replace indicator.
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.
User manual
Corrective maintenance
P/N 3-9008-553
November 2020
User manual
63