Thermo Scientific SOLA II, User Manual

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Thermo Fisher Scientific SOLA II User Guide J-1
Appendix J
Dual PMT Supply Option
The SOLA II Dual PMT Supply option was designed to address the need of
certain applications requiring sulfur measurements in fuels with a large
variation in the total sulfur concentration.
The typical applications where this option can be used are the inlet and outlet
of desulphurization reactors, batch process of different fuels, and dual stream
applications were the sulfur concentration expected on each stream varies by
a large factor.
Note
This option is not suitable for continuous monitoring of a stream where
large changes in sulfur concentrations are expected and continuous reporting
is necessary.
σ
During initial setup and calibration of a SOLA II, the optimum PMT supply
voltage is set so that the highest concentration expected produces a signal
that is within the range that the rest of the electronics can process. The
voltage applied to the PMT is a negative DC voltage, and the lower the PMT
voltage the greater the sensitivity of the detector.
Looking at previous applications as examples, a SOLA II calibrated for a full
scale range of 8000 ppm S w/w was set up with a PMT voltage of -570 Vdc,
and a SOLA II calibrated for a full scale range of 10 ppm S w/w was set up
with a PMT voltage of -950 Vdc.
The current dual range option on the SOLA II only modifies the scaling of the
4–20 mA output to provide higher output resolution at the low end of the
scale. The analytical calibration is always done on the highest range required.
The Dual PMT Supply option adds the capability of two independent
analytical calibrations. During setup and calibration, supply A is assigned to
one range and supply B to the other. The voltage on each supply is adjusted
using the corresponding POT to accommodate the desired range. The analyzer
is then calibrated and tested for each range. During normal operation, the
supply voltage to the PMT is routed from either supply under software
control.
Overview