6 Bath Use
tion. The fluid in the bath allows different types of probes to be calibrated at the same time. However, stem effect from different types of probes is not to- tally eliminated. Even though all baths have horizontal and vertical gradients, these gradients are minimized inside the bath work area. Nevertheless, probes should be inserted to the same depth in the bath liquid. Be sure that all probes are inserted deep enough to prevent stem effect. We suggest a general
When calibrating over a wide temperature range, better results can generally be achieved by starting at the highest temperature and progressing down to the lowest temperature.
Probes can be held in place in the bath by using probe clamps or drilling holes in the access cover. Other fixtures to hold the probes can be designed. The ob- ject is to keep the reference probe and the probe(s) to be calibrated as closely grouped as possible in the working area of the bath. Bath stability is maximized when the bath working area is kept covered.
In preparing to use the bath for calibration start by:
•Placing the reference probe in the bath working area.
•Placing the probe to be calibrated, the UUT, in the bath working area as close as feasibly possible to the reference probe.
6.3Calibration of Multiple Probes
Fully loading the bath with probes increases the time required for the tempera- ture to stabilize after inserting the probes. Using the reference probe as the guide, be sure that the temperature has stabilized before starting the calibration.
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