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4. Calibration
4.1 TRS Calibration
1. Connect a suitable dilution gas calibrator, such as the Ecotech GasCal-1100 to the input of the
thermal converter. Allow 15 minutes for the analyser to stabilise on zero gas.
Note: When the thermal converter is initially turned on, gases and material imbedded on the quartz
tube will usually take 60 minutes to burn off. As material burns off it may appear as SO2 or NO.
2. Perform a zero calibration on the analyser; the resulting zero offset generated by the converter
should not exceed 0.100ppm. Introduce span calibration gas at 80% of working range and then
perform a span calibration on the analyser.
3. Check the zero again and adjust if necessary.
4. To optimise the thermal converter temperature, introduce span gas of 100% of operating range.
Allow the thermal converter to stabilise, and then increase the thermal converter temperature by
25°C. Allow 15-25 minutes for the gas analyser value to stabilise.
As the temperature of the converter is increased, the span output will also increase until the
optimum thermal converter temperature is reached. If operated above the optimum temperature,
the efficiency will not be increased and the life of the catalytic material will be limited.
The life of catalytic material and quartz tube should last several years under normal usage. Multi
point calibration of the thermal converter is recommended at start-up and once per year.
4.2 Ammonia (NH3) Calibration
1. Connect a dilution gas calibrator, such as the Ecotech GasCal-1100, to the input of the thermal
converter with new FEP thick walled tubing, and use 1/8 glass lined stainless steel tubing from
the NH3 cylinder to the span input of GasCal-1100. Keep all tubing as short as possible.
Note: Use only Teflon tubing.
2. Allow 30 minutes for the analyser to stabilise on zero gas. When the thermal converter is initially
turned on, gases and material imbedded on the quartz tube and catalyst will usually take
approximately 60 minutes to burn off. As the material burns off, NOX or NO readings may be
observed on the analyser.
3. Perform a zero calibration from the analyser, the resulting zero offset generated by the converter
should not exceed 0.100ppm. Introduce span calibration gas at 80% of working range; perform a
span calibration on the analyser.
Note: NH3 span gas will be slow to respond.
HTO-1000 User Manual 1.5
Page 21