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 occasionally 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 Figure 28 .
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1 Gas Concentration 2 Sensor Current A Zero Point B Span Value (PPM, LEL, %Vol) |
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 for a complete list of gas compounds and corresponding tables and span values.