MESA LABORATORIES, INC. DataTrace Division
Standard
Operating
Procedure
Release Date: August 27, 2010
Page: 26 of 32
Revision B
We recommend that a recalibration be performed on a Tracer
only
when a drift in its temperature
accuracy is detected and verified. Furthermore, there are considerations related to the reference
environment that must be adhered to. If these requirements can not be met in the field, it is best
to return the Tracers to the factory for calibration and certification.
The minimum calibration dwell time in a
stable
environment is 20 minutes per
point. This means that the bath or isothermal block must have attained the target
temperature and stay at that temperature for at least 20 minutes for each point for
an acceptable calibration to be performed.
The stability of the reference environment is critical to a good calibration. The field
calibration requires 0.05°C environmental stability for the calibration to be
completed successfully. The factory calibration stability is 0.003°C.
The DataTrace
®
Temperature Calibration program allows great flexibility with respect to selecting
the appropriate calibration points to match the requirements of the application and also
accommodate changing needs and capabilities in the future. However, once the procedure is
initiated, instructions must be followed explicitly to complete the calibration process successfully.
Once implemented, the program leads the user automatically through the procedure by following
the instructions presented on the screen.
The temperature calibration program is entered from the Program Tracer window under the MAIN
Tab of the DataTrace Control Panel. Select Calibration Mode by clicking on that option.
Calibration Mode initiates the calibration process that creates, verifies, and installs new
calibration coefficients into a temperature Tracer in either a One Point or a Two Point Calibration
cycle. The calibration process starts when the Program button is pressed. However, the
calibration screens will not appear until the Tracer is retrieved from the reference environment
and then Read in the Calibration Utility.
A One or Two Point Calibration optimizes a Tracer to a particular process or application. In most
cases it is best to perform a two point field temperature calibration. In a two point calibration plan
for the lower target calibration temperature to be 10°C below the lowest process temperature and
the higher temperature should be 10°C above the highest process temperature. As a rule of
thumb, do not use a two point calibration where the range of interest is less than 75°C. For this
small of a range, use a one point calibration where the critical target temperature value is defined
to “focus” the calibration on that critical temperature. If a two point calibration with a range less
than 20°C is attempted a Range Error will be generated and the calibration will be aborted.
Procedure for a One or Two Point Temperature Calibration
The procedure for a One or Two Point Calibration is almost the same. The primary difference is
that for a two point calibration be prepared to expose the target Tracer to two temperature
environments during the process, and the Calibration Wizard will request information on two
references rather than just one. The procedure is listed below.
1. Select the Calibrate Mode option on the Program Tracer screen. The temperature
calibration procedure starts by automatically programming the Tracer with a special
program called “CALBRATE”. (Note the missing “i” in calibrate.) Press the Program
button.
When initiated, a dialog box appears, stating that the calibration program has been
loaded into the Tracer and that the Tracer must be placed into the appropriate reference
environment. Do this as soon as possible as the Tracer starts taking readings once each
minute beginning at the time it was programmed.
