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3.7AUTOMATIC FUNCTION (Optional)
The events talking place during a zero cycle are as follows:
l. The zero cycle starts with activation of the calibration contact. The analyzer outputs are held during the zero cycle.
2.The Auto Zero solenoid valve (optional) is activated and zero gas replaces the sample. (This valve may be internal or external to the Model 7300A enclosure).
3.At about minute one in the cycle. The Auto Zero board then begins its zeroing function, adjusting the processing circuitry of the analyzer to develop a zero signal output. During this period, the analyzer display may swing from below zero to above fullscale several times before it finally settles to zero output. The “hold” feature prevents these wide output excursions from affecting the analog output and trigger alarms. The Auto Zero circuit board function takes about 6 minutes to complete. It is important that zero gas is continually purging the cell during this time.
4.At around the 5th minute, the Auto Zero solenoid valve is deactivated and sample replaces the zero gas.
5.The hold feature is deactivated and the display starts reading the sample again, and the analog output soon starts tracking.
This concludes the zero cycle.
The time between zero cycles, may be programmed to last from one (1) to 23 hours.
For “Purity Measurements” typical zeroing is performed every 3 hours. This may increase or decrease depending upon the complexity of the application involved.
Teledyne Analytical Instruments |