Industrial Scientific TANGO TX2, Product Manual

Page: 45 / 48

39
Appendix A
Maintenance Definitions
Bump Test (or "functional test")
Bump testing is a functional test in which an instrument's installed sensors are to be briefly exposed to (or
“bumped” by) calibration gases in concentrations that are greater than the sensors’ low -alarm setpoints.
This will cause the instrument to go into low alarm and will indicate which sensors pass or fail this basic test
for response to gas.
Zero
Zeroing adjusts the sensors’ “baseline” readings, which become the points of comparison for subsequent
gas readings. It is a prerequisite for calibration. During zeroing, the installed sensors are to be exposed to
an air sample from a zero-grade-air cylinder or ambient air that is known to be clean air. If there are gases
in the air sample that are below the lowest alarm level, the instrument will read them as zero; its only task is
to
read the air sample as clean air. The user's task is to ensure the air is clean.
Calibration
Regular calibrations promote the accurate measurement of gas-concentration values. During calibration, an
instrument’s installed sensors are to be exposed to their set concentrations of calibration gases. Based on
the sensors’ responses, the instrument will self -adjust to compensate for declining sensor sensitivity, which
naturally occurs as the installed sensors are used or “consumed”.
Note: During calibration, the span reserve percentage value for each sensor is displayed. An indicator of a
sensor's remaining life, when the value is less than 50%, the sensor will no longer pass calibration