Galvanic Applied Sciences 943-TGXeNA, Operation Manual

Page: 38 / 149

Revision 5 38 August 2021
analyzer installation, including but not limited to steam temperature and pressure (both oven
steam and probe nozzle steam), ambient temperature, aspirator drive gas temperature, and
the quantity and quality of insulation applied to the steam lines, sample probe nozzle and
ball valve, and analyzer flange.
3.2.6 System Regulator
The system instrument air regulator is normally set to 30 psig. However, the specific value
of this setting is not critical for system operation provided that the pressure is sufficient to
provide adequate sample aspiration, system zeroing, and effective back purge. In situations
where additional supply pressure is required, the system regulator may be adjusted to its
maximum output of 50 psig without harming the analyzer.
As the cabinet cooler draws significant flow of instrument air, it is advisable to
do all adjustments of the zero and aspirator drive air with the cabinet cooler
switched on. In this fashion, deficiencies with the pressure and / or flow rate of
the instrument air supply can be immediately detected.
3.3 Analyzer Outputs
The 943-TGXeNA analyzer generates both analog and digital output signals for connection to
the users’ plant control system. The analog output signals are used to output calculated
concentration and other pertinent analysis values, and are user-configurable for range, output
parameter, and output behaviour. The digital output (relay) signals are used for outputting
analyzer and purge status signals.
3.3.1 Analog Outputs
There are four available analog outputs available on the 943-TGXeNA. The analog outputs
are all loop-powered 4-20 mA outputs which are fully user configurable for output parameter,
output range, and update behaviour when the analyzer is in back purge mode. Each analog
output can be configured to output one of the following parameters:
•
Air Demand (range starts at negative full scale for 4 mA)
• H
2
S Concentration (% or PPM)
•
SO
2
Concentration (% or PPM)
•
COS Concentration (% or PPM)
• CS
2
Concentration (% or PPM)
• H
2
S:SO
2
Ratio
•
Sigma S (sum of H
2
S and SO
2
concentrations)
Each analog output can also be user configured to be either Track or Hold . Track and hold
refer to the behaviour of the analog output when the analyzer is placed in back-purge mode.
If an output is programmed to be Track, the output value will track along with the calculated
values when the analyzer is placed in back purge mode, and thus will go to zero (4 mA)
when the analyzer is in back purge mode. If an output is programmed to be Hold, it will hold
the last known good value from when the analyzer was in sampling mode and continue to
output this good concentration value until the analyzer goes back into sampling mode. Thus,
the analog output will NOT go to 0 (4 mA) when the analyzer is in back-purge mode.
Typically, an analog output configured to output air demand will be configured for Hold, while