3 Operation | Model 6600 | |
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Zero off: 0.0 ppm <ENT> to begin Zero
The offset value can be modified by using the Up/Down keys. Next section shows how to select this value. Suffice to say that whatever value you enter, will be automatically added to the reading. Thus, if you entered
Once the Enter key is pressed the instrument enters the zero mode. If you chose AUTO zero mode, the instrument will do the work of bringing the reading back to zero plus the offset value that was entered. If you chose MANual zero mode, thenyoumustenterinputtotheinstrumentasexplainedinthecorresponding sectionofthemanualbutwithonedifference:insteadofbringingthedisplayto read zero, you must make the display read zero plus the value entered as offset.
How the offset value is selected:
To find out what the offset value should be, the intended zero calibration gas and the a mix of the process background gas must be procured. This of course assumes that the zero gas and the process background gas are very different and thatanoffsetwilloccur.
1.Let the intended zero calibration gas flow through the 6600 sample cell (this assumes that you have started up you system as recommended by the manual or technical personnel) and do a zero on the instrument. Leave the offset set to zero value.
2.At the end of the zero function, make sure the analyser reads zero.
3.Flow the process background gas mix through the 6000 sample cell on the Analyse mode. Wait for the reading to become stable. Write the reading down. Change the sign of the reading: This is the offset to be entered.
4.Do a manual run to check. Reintroduce the zero calibration gas. Start a zero on the analyser but this time enter the offset value.
5.At the end of the zero function, check that the instrument reads the entered offset.
6.Reintroduce the process background gas mix to the 6000 sample cell in the Analyse mode. It should read close to zero once the reading is stable (+/- 1% erroroffullscale).
Spanning the 6600:
Since the instrument might be spanned with background gas the same as the zero calibration gas, the span value to be entered should be the span concentrationplustheoffsetvalue(iftheoffsetvaluehasaminussignthen algebraicallyitbecomesasubtraction).
Teledyne Analytical Instruments