Teledyne 6400EH - Sulfur Dioxide Analyzer - Manual (Page 55)

UV Fluorescence SO2 Analyzer Troubleshooting
Teledyne Analytical Instruments 43
Troubleshooting & Repair
For the most part the information contained in Chapter 11 of the
6400E Manual is also applicable to the 6400EH. There are a few
exceptions however.
10.1.1 Fault Diagnosis with Warning Messages
Table 10-1: Warning Messages - Indicated Failures
WARNING
MESSAGE
FAULT CONDITION POSSIBLE CAUSES
VACUUM
PRESS
WARN
Gas pressure inside the
reaction cell outside of
warning limits.
If sample pressure is > 10 in-Hg:
o
Pneumatic Leak
o Bad Pump→Rebuild Pump
o
Failed pressure sensor/circuitry
10.1.2 Fault Diagnosis with Test Functions
Table 10-2: Test Functions - Possible Causes for Out-Of-Range Values
TEST
FUNCTION
NOMINAL
VALUE(S)
POSSIBLE CAUSE(S)
VAC < 9.1 IN-HG-A
Incorrect sample gas pressure could be due to: pneumatic leak;
malfunctioning valve; malfunctioning pump; clogged flow orifices;
sample inlet overpressure; faulty pressure sensor
10.2 Subsystem Checkout
10.2.1 Pneumatic Sensor Assembly
The pneumatic sensor assembly of the 6400EH differs from that of
the 6400E in that there is no flow sensor. Instead the assembly includes
two pressure sensors located on either side of a critical flow orifice. The
6400EH software infers the gas flow rate by mathematically comparing
the two pressure readings.