Alicat LC Series Liquid Flow Controller - Manual (Page 40)

40
TROUBLESHOOTING
Display does not come on or is weak.
Check power and ground connections and supply voltage. Please reference
the technical specifications (page 51-56) to assure you have the proper power
for your model.
Flow reading is approximately fixed either near zero or near full scale regardless of
actual line flow.
Differential pressure sensor may be damaged. A common cause of this problem
is instantaneous application of high pressure as from a snap acting solenoid
valve upstream of the meter. If you suspect that your pressure sensor is
damaged please discontinue use of the device and contact Alicat.
Displayed volumetric flow, pressure or temperature is flashing and message
VOV, POV or TOV is displayed:
Our flow meters and controllers display an error message (VOV = volumetric
overrange, POV = pressure overrange, TOV = temperature overrange) when
a measured parameter exceeds the range of the sensors in the device. When
any item flashes on the display, neither the flashing parameter nor the flow
measurement is accurate. Reducing the value of the flashing parameter to
within specified limits will return the unit to normal operation and accuracy. If
the unit does not return to normal contact Alicat.
Meter reads negative flow when there is a confirmed no flow condition.
This is an indication of an improper tare. If the meter is tared while there is
flow, that flow is accepted as zero flow. When an actual zero flow condition
exists, the meter will read a negative flow. Simply re-tare at the confirmed
zero flow condition. Also note that while the meter is intended for positive
flow, it will read negative flow with reasonable accuracy (it is not calibrated for
bi-directional flow) and no damage will result. See TARE page 19 .
After installation, there is no flow.
LC-Series controllers incorporate normally closed valves and require a set-point to
operate. Check that your set-point signal is present and supplied to the correct pin
and that the correct set-point source is selected under the SETPT SOURCE list in
the control set up display (page 28). Also check that the unit is properly grounded.
My controller does not respond to the set-point.
Check that your set-point signal is present and supplied to the correct pin and
that the correct set-point source is selected under the SETPT SOURCE list in the
control set up display (page 28). Also check that the unit is properly grounded.
The flow lags below the set-point.
Be sure there is enough pressure available to make the desired flow rate. If
either the set-point signal line and/or the output signal line is relatively long, it
may be necessary to provide heavier wires (especially ground wiring) to negate
voltage drops due to line wire length. An inappropriate PID tuning can also
cause this symptom if the D term is too large relative to the P term (page 30).