When melting copper, a lance pyrometer can be used to measure the temperature of the liquid copper. An assembled pyrometer, which is shown in the upper right-hand corner of Figure 9.7.1, uses a type-K thermocouple in a replaceable, graphite-sheathed tip, which is inserted into the liquid copper. Either digital or analog readouts are available. The graphite-sheathed thermocouple will survive numerous insertions into the liquid copper before it will need to be replaced.
Typically lance pyrometers that are inserted into the liquid copper can provide more accurate temperature readings than non-contact optical pyrometers.
Figure 9.7.1: Photograph of a MIFCO Model MT-400 lance pyrometer