4-3
Brooks
®
Model SLA5840
Section 4 Maintenance
& Troubleshooting
Installation and Operation Manual
X-PR-SLA5840-Series-RevB-RT-eng
Part Number: 541B201AAG
October, 2017
a. Problem: No response to input commands/No output status signal.
1. The unit may not be receiving power. Check that module status LED
is green.
2. Connections may not be secure. Check all cable connections.
b. Problem: Flow/flow signal doesn't reach setpoint.
Failure of the flow rate or flow signal to achieve setpoint could be caused
by a number of factors:
1. Insufficient pressure drop across the MFC (low or no pressure).
If there is not enough pressure differential across the MFC, it is
impossible for the MFC's valve orifice to pass the full scale flow rate. To
check for this condition, compare the actual inlet/outlet pressure drop as
read from pressure gauges with that specified on the order (shown in
Figure 4-1). Increase the pressure if necessary.
2. Clogged sensor tube. If the sensor tube is clogged, the flow signal will
be very low or zero while the actual flow will be at the valve's maximum rate.
3. Clogged restrictor. If the restrictor becomes clogged, a much
larger portion of the flow stream will pass through the sensor rather
than going straight through the restrictor. The symptom of this condition
is a substantially reduced actual flow with a flow signal that matches the
setpoint.
4. Valve Override pin is active. If the valve override pin is active, the
valve will be forced open or closed. Set this pin to its normal level before
setting a setpoint.
Figure 4-1 Bench Troubleshooting Circuit (Flow mode)
