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TXP-WTA_Instruction_Manual_(Rev1.3)
CAL Mode – Routine Calibrations
NOTE: Calibration is the most important function for ensuring correct gas readings at the TXP-WTA Sensor
Transmitter.
The CAL MODE (flow chart shown in Figure 5-3) is designed to make calibration quick, easy and error free. A
successful ZERO and SPAN calibration requires only four keystrokes. CAL MODE is always followed by an adjustable
CAL PURGE time period (see Section 8.2.2). CAL PURGE holds the output at a safe value to prevent alarms being
tripped by the upscale span calibration gas.
Follow these TXP-WTA Sensor Transmitter calibration guidelines:
Calibration accuracy is only as good as the calibration gas accuracy. TracXP recommends calibration gases
•
with NIST (National Institute of Standards and Technology) traceable accuracy to increase the validity of the
calibration.
•
Do NOT use Cal Gas that has been stored for extended periods of time in temperatures outside of the
specifications printed on the label (example: in a hot vehicle). This can reduce the level of H2S in calibration
gas significantly, for example.
Do not use a gas cylinder beyond its expiration date.
•
•
Always calibrate a sensor before installation.
•
After applying gas, allow the reading to stabilize before span calibration. (usually 2 minutes)
Calibrate on a regular schedule. (TracXP recommends once every 3 months, depending on atmospheric
•
conditions, exposure to target gas, poisons and contaminants.)
Calibrate only in a clean atmosphere, which is free of background gas.
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REV – 1.3
Figure 6-2 – Calibration Gas Input
[34-2900-0207-4 ]
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