Measurements of Electrical Resistance ER

5 = temperature sensor in the heat transfer medium 6 = resistance heating 7 = highly insulated sensor head 8 = shielded cable  

The use of an ER measuring system and the interpretation of the results require some familiarization with the possibilities and limitations of the method. 

One of the advantages of ER compared with other methods discussed later is the dimensions of the sample, especially its thickness of 10-15 mm. This is comparable to frequently used filling heights of vials for pharmaceutical products. If the cake thickness is substantially larger, e.g. 40 mm, the freezing rates in a study should be chosen accordingly 1 °C/min cannot be expected with freezing on the shelves 0.2 or 0.3 °C/min is more likely. Therefore, tests for these thicknesses may be carried out, e.g. at 0.15,0.25 and 0.35 °C/min. 

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