Analysis Problems; No Peaks - ABB PGC2000 Operation And Service Manual

a. Electrical noise from the FPD amplifier could result from a noisy power supply or defective
component of the PCB.
b. Loose electrical connections can cause electrical signals to be sporadic.
c. Since the FPD amplifier input impedances are extremely high, low noise coaxial cable
connects the detector and the FID amplifier. Defective coaxial cables or poor electrical
connections are often sources of noise.
2. Contamination can enter through the burner air, burner fuel, or carrier. Secondary sources are
contaminated air, fuel, carrier lines, or regulators.
a. Sulfur-bearing contaminates in carrier gas, hydrogen fuel or air can cause the FPD to
produce an output signal as they are burned.
b. The gases may be pure, but contaminated tubing or hardware components in the analyzer or
cylinder regulator(s) contaminate the makeup gases as they pass through them. The FPD
detects theses contaminants, resulting in a noisy baseline.
c. If water accumulates in the FPD vent, the detector effluent flow can bubble through the
accumulated water. This in effect back-pressures the FPD, causing the flame intensity to
fluctuate. This can appear as a noisy baseline as well.
Perform Test Procedure 11 (Common Usage of Gases) or Test Procedure 14 (Coaxial Cable), as
applicable. Replace or clean the FPD (see "FPD REPAIR" in Section 8).

ANALYSIS PROBLEMS

No Peaks

Symptom: No peaks are indicated on strip chart recorder, graphic display, or detector signal (see
Figure 6-8).
BASELINE
Cause: This generally indicates that either no sample was injected, or the injected sample is not
being detected or processed.
No peak detection could be caused by any one of the following:
1. Chroma not selected on manual control screen (affects recorder output only).
2. No sample flowing to the sample valve. Verify sample is flowing to the sample valve.
3. No carrier gas supplied to the analyzer. Perform Test Procedure 1 (Carrier, Makeup, and Utility
Gas Supplies) and Test Procedure 2 (Carrier and Makeup Gas Flow Adjustments).
4. No air to the sample valve actuator. Perform Test Procedure 18 (Sample Valve Actuation Air).
6-6
TIME
NORMAL
Figure 6-8. NO PEAKS
Missing Peaks
BASELINE
TIME
OFFSET
2000-OSM, F1