Fluke RUSKA 2456-LEM, User Manual

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5-1
Chapter 5
Calibration
Span
Pressure - On Board Sensor
Calibration Point 1: 10.5 +/-0.25 psia
Calibration Point 2: 15.0 +/-0.25 psia
Temperature
Calibration Point 1: 17 +/- 2 degC
Calibration Point 2: 29 +/- 2 degC
Zeroing
Temperature measuring devices are impacted by self heating. The rise in temperature,
measured by the sensor, is a function of the amount of heat generated by the probe and
the ability of the probe to dissipate this heat. Air flow around the probe improves the heat
dissipation and thus lowers the rise in temperature. When a temperature probe is
calibrated in a high flow chamber and used in a low flow environment, then the error due
to self heating is maximized. This error can be minimized by zeroing the sensor in the
operating environment with respect to an appropriate standard.
The LEM software allows the technician to perform a zero offset. The zero offset is
prompted following the span calibration. After the span calibration is finished, the high
air flow chamber can be turned off and the LEM can be zeroed in a low air flow
environment that is typical of its operating environment.
The reference probe should be placed at a distance of 3 or more inches in front of the
LEM temperature sensor.
Both the span calibration and zeroing operation are password protected.
Humidity
The humidity calibration must be done after the Temperature calibration. The two
calibration points must be different by at least 25%RH.
A suggested method:
Point 1: applied vacuum -> 0%RH
Point 2: ambient humidity (25%RH or higher)