MAHLE RTI NTF-15H - Manual (Page 5)

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4. Press and hold the Calibration Key for three seconds until the display reads “CAL”. This
will calibrate the Nitrogen Tester to room air. Thereafter, calibration is recommended on a
weekly basis.
A new calibration is required when:
! The measured N
2
percentage in 79.1 percent N
2
is above 80.1 percent N
2
! The measured N
2
percentage in 79.1% N
2
is below 78.1 percent N
2
! If unsure about the displayed N
2
percentage (see Factors influencing accurate
readings).
5. The Nitrogen Tester is ready to use.
OPERATION PRINCIPALS
The instrument display corresponds directly to the oxygen sensor. The oxygen diffuses
through the membrane and an electrical current is generated that is proportional to the partial
pressure of oxygen in the gas sample. The oxygen percentage is subtracted from 100, with
the remainder being displayed as percent nitrogen. The sensor has a minimal response to
gases other than oxygen.
FACTORS INFLUENCING ACCURATE READINGS
Elevation Changes
! Changes in elevation result in a reading error of approximately 1 percent of reading
per 250 feet.
! In general, calibration of the Nitrogen Tester should be performed when elevation
at which the product is being used changes by more than 500 feet.
Temperature Effects
The Nitrogen Tester will hold calibration and read correctly within ±3 percent when in thermal
equilibrium within the operating temperature range. The device must be thermally stable when
calibrated and allowed to thermally stabilize after experiencing temperature changes before
readings are accurate. For these reasons, the following is recommended:
! For best results, perform the calibration procedure at a temperature close to the
temperature where analysis will occur.
! Allow adequate time for the sensor to equilibrate to a new ambient temperature.
CAUTION: “CAL Err St” may result from a sensor that has not reached thermal
equilibrium.