ENERAC 700, Instruction Manual

Page: 43 / 74

43
SPAN TIME: When carrying out a span calibration, you must introduce the span
gas for an appropriate amount of time before the analyzer executes the span
calibration. This setting, which is the same for all sensors, controls this time
interval. The time is indicated in seconds, but a minimum of 2 minutes of span gas
feeding is required for proper calibration.
For NO and CO calibrations 4 minutes
is recommended. For NO
2
and SO
2
calibrations 8 minutes is recommended.
SPAN XXXX: The remaining lines of the SPAN MENU are used for carrying out
span calibrations of the individual CO, NO, NO
2
, SO
2
, NDIR, combustibles, and
stack draft/velocity sensors
A. AUTOZEROING THE INSTRUMENT
When you turn the instrument on, you can press the
ENTER
key to begin an
autozero straightaway. To start the autozero procedure at any time, press the
ZERO/SPAN
key and choose:
Zero All Sensors
. The autozero countdown will
commence.
• Check that the probe’s sampling line and electrical connections are secure.
• Check that the probe tip is at room temperature.
It is very important that at the moment of "zeroing" the probe tip is at room
temperature and the environment is clean and free of carbon monoxide or other
gases. It may be a good idea to zero the analyzer outdoors, before entering the
facility. Some protocols, such as EPA’s Method 7E, require a cylinder of certified
zero gas for zeroing the analyzer.
At the end of the autozero period all of the sensors are calibrated to their zero-
point. All sensors will read zero, except for oxygen, which will read 20.9%, and
the temperature sensors, which will read the ambient temperature.
NOTE: In practice AUTOZEROING is only needed once at the beginning of a day
of measurements. The analyzer will not have sufficient zero drift during the next 24
hours to require additional autozeroing procedures.
If you have the NDIR option, the analyzer must be autozeroed when the unit is
turned on.
If no error messages appear at the end of the countdown then you may proceed
with your measurements.