The CellaCast PX 81 has been specially developed for measuring the temperature of liquid metals in pouring troughs of blast furnaces and cupolas. Furthermore, the pyrometer is used when transferring the metal from the melting or holding furnace into the transport or pouring ladle. The ratio pyrometer is equipped with a separate optical measuring head and a light guide. The light guide and measuring head are insensitive to interference from electromagnetic radiation and can be used in ambient temperatures up to 250 °C without cooling. The variant with a separate optical measuring head is particularly advantageous in confined spaces.