The Zero And Span Functions; Zero Cal - Teledyne 7120 Operating Instructions Manual

4 Operation
4.4

The Zero and Span Functions

(1) The Model 7100 can have as many as three analysis ranges plus a
special calibration range (Cal Range); and the analysis ranges, if more than one,
may be programmed for separate or identical gas applications.
(2) If all ranges are for the same application, then you will not need the Cal
Range. Calibrating any one of the ranges will automatically calibrate the others.
(3) If: a) each range is programmed for a different gas application, b) your
sensor calibration has drifted less than 10 %, and c) your Cal Range was cali-
brated along with your other ranges when last calibrated, then you can use the
Cal Range to calibrate all applications ranges at once.
If your Model 7100 analyzer fits the paragraph (3) description, above, use
the Cal Range. If your analyzer has drifted more than 10 %, calibrate each range
individually.
CAUTION: Always allow 4-5 hours warm-up time before calibrat-
ing, if your analyzer has been disconnected from its
power source. This does not apply if the analyzer
was plugged in but was in STANDBY.
The analyzer is calibrated using reference, zero, and span gases. Gas
requirements are covered in detail in chapter 3, section 3.4 Gas Connections.
Check that calibration gases are connected to the analyzer according to the
instructions in section 3.4, observing all the prescribed precautions.
Note: Shut off the gas pressure before connecting it to the analyzer,
and be sure to limit pressure to 40 psig or less when turning it
back on.
Readjust the gas pressure into the analyzer until the flowrate through the
sensor settles between 50 to 200 cc/min (approximately 0.1 to 0.4 scfh).
Note: Always keep the zero calibration gases flow as close as the
flowrate of sample gas as possible

4.4.1 Zero Cal

The ZERO function in the MAIN MENU is used to enter the zero calibra-
tion function. Zero calibration can be performed in either the automatic or manual
mode.
CAUTION: If you are zeroing the Cal Range by itself (multiple
application analyzers only), use manual mode
zeroing.
4-16 Teledyne Analytical Instruments
Model 7120