Ametek Thermox WDG-VRM, User Manual

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System Overview
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1-5
where R and F are constants, T is absolute temperature, and O
1
and O
2
are the
oxygen partial pressures on either side of the cell.
For measuring oxygen in non-combustibles gases, the calibration of an analyzer
is obtained from the formula:
Where A is a constant, T is the cell temperature on an absolute scale (°C +
273) and O
2
Unk% is the unknown oxygen concentration of the gas to be
analyzed(calculated by the analyzer).
The cell produces zero voltage when the same amount of oxygen is on both sides,
and the voltage increases as the oxygen concentration of the sample decreases.
The voltage created by the difference in the sample gas and the reference air is
carried by a cable to the microprocessor control unit, where it is linearized to an
output signal.
Because of the high operating temperature of the cell, combustible
gases that are present may burn. When this occurs, the cell will
generate high millivolts and cause the display to indicate less oxygen
than is actually in the gas (net oxygen content).
NOTE

AT = 45.78 at 650°C E = A*T*Log
20.9%
O
2
Unk%