Teledyne LXT-280 - Manual (Page 19)

Dissolved Oxygen Transmitter Installation
Teledyne Analytical Instruments 9
2.4 Configuring the LXT-280
The LXT-280 Transmitter is used for measurement and control in
hazardous environments for a wide range of liquid analytical
applications. This manual describes the configuration for use in
dissolved oxygen measurement and control applications. The unit is
Factory Mutual approved as intrinsically safe for use in Class I, II, and
III Divisions 1 Groups A through G hazardous areas.
Configuring the instrument is described in Section 3 of this manual.
2.5 Calibration
Prior to using the instrument for the first time, the LXT-280 must
be calibrated. The specific calibration procedure used depends on the
application. Among other things, the calibration routine establishes the
correspondence between the 4-20 mA output signal and the application
dependant measurable parameter.
Calibration can be performed without disturbing control or recorder
functions using a manual output mode (see Section 4.2). Typically, the
calibration is done using either a one-point buffer calibration
(standardization) or two-point (span) calibration. There is also a Back to
Factory calibration feature which resets the LXT-280 to “nominal
electrode” situation. This reverts to an electrode with zero millivolts
offset at zero percent or ppm oxygen and a full scale output of –400 mV.
This is useful as a starting point if the instrument has been mis-
calibrated.
The calibration routines require a familiarity with the instrument
operation and is described after fundamental operational parameters are
discussed in Section 3.