53
Calibration
5.5
Calibration Types: Zero vs. Span
The TG5000 has two types of calibration: Zero and Span calibration.
Zero Calibration resets the baseline level reading to zero. If the target gas is suspected to be occa-
sionally present, it is best to also use a zero gas cylinder during the zero calibration. If the target
gas is not present in the atmosphere, an additional calibration cylinder is not required.
The "Calibrate" option involves first applying a zero gas followed by the span gas. The span gas
is a known concentration of gas which adjusts the accuracy and precision of the transmitter to the
known value; this is referred to as the “Span Value. See Fig. 25.
Fig. 25 Calibration Curve
The Sensor Span Value in the device menu should be the same as the concentration listed on the
calibration gas cylinder; unless an LEL simulant gas is being used.
The XIR Plus sensor can be calibrated to a wide variety of gas compounds using either 0.1 %
propane, 0.6 % propane, or 2.5 % methane, and MSA's gas table. See Tab. 21 for a complete list
of gas compounds and corresponding tables and span values.
US
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