Forma Scientific 3158 - Page 46

Forma Scientific, Inc.
7-3
Symptom Possible Cause
Problem 12: CO
2
setpoint cannot be
changed.
• Defective CO
2
control.
Problem 13: Unit cannot be zeroed. • Defective CO
2
potentiometer.
• Defective zero control.
• Defective CO
2
Sensor.
Problem 14: CO
2
overshoots setpoint
badly.
• Inoperative CO
2
sampler blower.
• Defective CO
2
control.
• CO
2
inlet pressure too high.
• Unit is in over temp.
Problem 15: Actual CO
2
is higher than
setpoint and readout. Re-zeroing helps
for a time, then symptoms return.
• Defective CO
2
sensor.
• Incorrect calibration of CO
2
control.
Problem 16: CO
2
alarm sounds while
CO
2
level is controlling at setpoint.
• Excessive RFI or EMI near unit.
• Faulty grounding circuit.
• Defective CO
2
control.
Problem 17: CO
2
setpoint changes by
itself.
• Faulty CO
2
potentiometer.
• Defective CO
2
control.