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MODEL 700 CONTROL VALVE
User manual
P/N 3-9008-553
10
Corrective maintenance
10.1
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
(1)
User manual
54
www.Daniel.com
Condition
Probable cause
Valve will not open
Upstream valve is
closed
Pump is not operating
Downstream valve is
closed
Insufficient pressure
Clogged strainer
Swollen O-rings
Valve opens too slowly Valve inlet pressure
below normal
Swollen O-rings
Check "X" port
sensitivity control
needle valve position
(maybe closed too
much)
Valve will not close off
Bent indicator stem
tightly
Foreign material in
main valve piston seat
Swollen O-rings
Piston or seat O-ring
cut or defective
Refer to
Mechanical disassembly
(1)
Correction
Open upstream valve.
Start pump and check for cavitation.
Open downstream valve. (Check coupler on
bottom loading units and internal valve in
truck.)
Check pump. Check bypass and strainer located
in line.
Clean strainer.
Disassemble valve and replace O-rings. Check
compatibility of O-rings with product.
Check strainer and pump for obstruction.
Disassemble valve and replace O-rings. Check
compatibility of O-rings with product.
Open sensitivity control needle valve.
Replace indicator.
Disassemble valve and inspect piston.
Disassemble valve and replace O-rings. Check
compatibility of O-rings with product.
Disassemble valve and replace if necessary.
procedures.
Corrective maintenance
November 2020
63
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