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Theory of Operation Teledyne API T703 Calibrator Operation Manual
176
9.6.4.2. Pneumatic Sensors for the O
3
Photometer
The several sensors located on the pneumatic sensor just to the left rear of the O
3
generator assembly measure
the absolute pressure and the flow rate of gas inside the photometer’s absorption tube. This information is used
by the CPU to calculate the O
3
concentration of the sample gas (See Equation 9-7). Both of these
measurements are made downstream from the absorption tube but upstream of the pump. A critical flow orifice
located between the flow sensor and the pump maintains the gas flow through the photometer at 800 cm
3
/min.
The following TEST functions are viewable from the instrument’s front panel:
PHOTO FLOW - The flow rate of gas through the photometer measured in LPM.
PHOTO SPRESS – the pressure of the gas inside the absorption tube. This pressure is reported in
inches of mercury-absolute (in-Hg-A), i.e. referenced to a vacuum (zero absolute pressure). This is not
the same as PSIG.
07223B DCN6378