2.3
Calibration
In order for any instrument to be used as a standard it must be calibrated. Each
PRT is calibrated in Hart Scientific’s calibration laboratory and provided with a
NIST traceable “Report of Calibration”.
At the time of purchase, the 5624 is calibrated from the Triple Point of Water to
the Silver Point (0.1°C to 961.78°C) at specified ITS-90 fixed points. Gener-
ally, a secondary PRT is calibrated by comparison method. All PRTs calibrated
by Hart Scientific are calibrated using standard calibration techniques.
2.4
Recalibration
The recalibration of the 5624 Secondary PRT should be scheduled according to
the user’s company Quality Assurance (QA) requirements. Normally, a PRT is
recalibrated recalibrated at least annually. A shorter calibration cycle can be re-
quired to meet QA requirements. Unless the PRT is used only over a limited
range, calibration over the full range of the PRT (0.1°C to 961.78°C) is recom-
mended. For information on recalibrating your 5624, contact your Hart Scien-
tific Authorized Service Center (see Section 1.4).
Depending on the user’s Quality Assurance requirements, the PRT drift should
be checked periodically at the Triple Point of Water (TPW). Section 8, Trouble-
shooting, provides information on drift with respect to mechanical shock and
oxidation. If the R
tp
cannot be restored after annealing to within calibration tol-
erances, a full recalibration should be scheduled.
5624 Platinum Resistance Thermometer
User’s Guide
8
