DANIEL 700 - Corrective Maintenance; Control Valve Troubleshooting

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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