Symptom
Cause
Remedy
The loop pressure
is acceptable but
there is little or no
flow.
The needle valve (NV1) is closed
too much.
Turn needle valve counter clockwise to increase
the flow.
Configuration 3 and 4, the plug
valve (PV) may be open.
Close the plug valve (PV).
If zero flow indicated, the
flowmeter pointer is not
following float position.
1/4 in. FLM, close the metering valve and wait for
one minute. Slowly open the metering valve and
adjust flow to desired rate. 1/2 in. FLM, close the
needle valve and wait for one minute. Slowly open
the needle valve and adjust flow to desired rate.
The flowmeter float is stuck in
the tube.
Adjust the flow rate with the needle valve (NV1)
and observe whether the flowmeter indicates the
changes.
Flush the system with solvent to remove oil and
solid deposits.
Remove the flowmeter and clean the inside of the
flow tube.
Replace the flowmeter.
One of the bypass valves is not
fully closed.
Move the black handle to the right and verify the
two ball valves (BV1/BV2) are fully closed.
Release set screws, reposition handle, and
retighten set screws.
Fast-loop pump (if used) is
damaged.
Check the rotation speed of the fast-loop pump.
Check the flow rate from pump – repair or replace
pump, as necessary.
The fast-loop return line or
process return nozzle is partially
or fully blocked.
Check that all valves in fast loop system external
to FLM are fully open.
The process return pressure is
too high.
Find a lower pressure point for return to process.
During initial startup the flow is
too low, the fast-loop supply line
may be too small or too long.
Replace the fast-loop supply and return lines with
larger tubing.
Troubleshooting
A Swagelok Pre-Engineered Subsystem Fast Loop Module
21
