Teledyne 6200T - Sulfides Analyzer - Manual (Page 277)

6200T Total Sulfur Analyzer Troubleshooting
Teledyen Analytical Instruments 277
12.8. M501TS Converter Maintenance
Maintenance on the M5401TS Thermal Converter includes:
 Changing the Quartz Tube
 Checking the Converter Efficiency
 Sample Diluter Maintenace
 Replacing a Thermocouple.
12.8.1. Changing the Quartz Tube
Over time, it may be necessary to change the quartz tube. Refer to the following
procedure for removing and replacing the heater tube.
 Turn off M501TS and allow it to cool to room temperature (~2 hours).
 See Figure 12-18 – M501TS Layout
 Remove the screws from the top inside of the front panel and fold panel
downward.
 Loosen front and rear fittings at each end of the tube.
 Carefully slide the tube out of the heater – the ceramic bushings at each end
of the heater are very fragile.
 Slide the new tube into the heater, and re-connect the fittings.
 Leak check the unit.
 Replace the thermocouple making sure that it is fully inserted into the
indentation in the body of the quartz tube.
 Check the converter efficiency. See the Section below.
12.8.2. Checking the Converter Efficiency
After maintenance it is good practice to check the converter efficiency. To check the
converter efficiency, perform the following procedure:
1. Produce a calibration gas of 400 ppb H
2
S in CO
2
at a flow greater than the
demand of the instrument; vent the excess gas out of the room.
 When using a calibrator or gas blender to generate H
2
S span gas (either
permeation tube or tank) with CO
2
gas as the diluent, please remember that
rotameters and mass flow controllers are calibrated with air or nitrogen.
Using them with CO
2
will produce large calibration errors (as large as 30%
or more), since CO
2
gas has considerably different characteristics. Contact
the manufacturer of your mass flow measurement/control device for
instructions on how to use it to measure CO
2
flow. Or use a flowmeter such
as a soap bubble, or BIOS – DryCal flowmeter that measures volume flow.
2. Allow the 6200T to stabilize at span for at least 30 minutes.
3. Check the converter efficiency by adjusting the converter’s temperature
controller set point:
 Starting at the converters normal set-point of 1000 o C, lower the set-point
temperature of the Converter in 5 o C increments (allowing 10 minutes
minimum settling time between increments) until a drop of approximately