Teledyne 6200T - Sulfides Analyzer - Manual (Page 248)

Troubleshooting Model 6200T Total Sulfur Analyzer
248 Teledyne Analytical Instruments
 Carry out an optical test using the OPTIC TEST procedure in the
diagnostics menu, refer to Section 5.9.4. If this test results in a
concentration signal, then the PMT sensor and the electronic signal path are
operating properly. If the M passes both ETEST and OTEST, the
instrument is capable of detecting light and processing the signal to produce
a reading. Therefore, the problem must be in the pneumatics, optics or the
UV lamp/lamp driver.
12.4.3. Unstable Zero and Span
Leaks in the 6200T or in the external gas supply and vacuum systems are the most
common source of unstable and non-repeatable concentration readings.
 Check for leaks in the pneumatic systems as described in Section 11.3.6.
Consider pneumatic components in the gas delivery system outside the
6200T such as a change in zero air source (ambient air leaking into zero air
line or a worn-out zero air scrubber) or a change in the span gas
concentration due to zero air or ambient air leaking into the span gas line.
 Once the instrument passes a leak check, perform a flow check (refer to
Section 11.3.7) to ensure that the instrument is supplied with adequate
sample gas.
 Confirm the UV lamp, sample pressure and sample temperature readings
are correct and steady.
 Verify that the sample filter element is clean and does not need to be
replaced.
12.4.4. Inability to Span - No SPAN Button
In general, the 6200T will not display certain control buttons whenever the actual value
of a parameter is outside of the expected range for that parameter. If the calibration
menu does not show a SPAN button when carrying out a span calibration, the actual
concentration must be outside of the range of the expected span gas concentration,
which can have several reasons.
 Verify that the expected concentration is set properly to the actual span gas
concentration in the CONC sub-menu.
 Confirm that the SO
2
span gas source is accurate.
 If you are using bottle calibration gas and have recently changed bottles,
bottle to bottle variation may be the cause.
 Check for leaks in the pneumatic systems as described in Section 12.6.1.
Leaks can dilute the span gas and, hence, the concentration that the analyzer
measures may fall short of the expected concentration defined in the CONC
sub-menu.
 If the physical, low-level calibration has drifted (changed PMT response) or
was accidentally altered by the user, a low-level calibration may be
necessary to get the analyzer back into its proper range of expected values.
One possible indicator of this scenario is a slope or offset value that is
outside of its allowed range (0.7-1.3 for slope, -20 to 150 for offsets). Refer
to Section 12.7.2.8 on how to carry out a low-level hardware calibration.