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Principles of Operation Teledyne API – Model T700 Dynamic Dilution Calibrator
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10.2.2. INTERNAL GAS PRESSURE SENSORS
The T700 includes a single pressure regulator. Depending upon how many and which
options are installed in the T700 calibrator, there are between two and four pressure
sensors installed as well.
In the basic unit a printed circuit, assembly located near the front of the calibrator near
the MFCs includes sensors that measure the pressure of the diluent gas and the source
gas currently selected to flow into the calibrator. The calibrator monitors these sensors.
Should the pressure of one of them fall below 15 PSIG or rise above 36 PSIG a
warning is issued.
In units with the optional O
3
generator installed a second PCA located at the rear of the
calibrator just behind the generator assembly includes a sensor that measures the gas
pressure of the zero air flowing into the generator. A regulator is also located on the gas
input to the O
3
generator that maintains the pressure differential needed for the critical
flow orifice to operate correctly.
Should the pressure of one of this sensor fall below 15 PSIG or rise above 25 PSIG
a warning is issued.
In calibrators with O
3
photometers installed, a second pressure located on the rear PCA
measures the pressure of gas in the photometer’s absorption tube. This data is used by
the CPU when calculating the O
3
concentration inside the absorption tube.
06873B DCN6388