Handheld thermocouple measurement

A handheld thermocouple measurement device and an IR temperature sensor are very important to have for understanding the performance of the extruder. These devices have been discussed previously in this chapter. In many of the case studies presented later, the extrudate temperature was measured by immersing a handheld thermocouple probe into the extrudate. The entire probe length is immersed or draped in the extrudate to minimize heat conduction to cooler parts of the probe. The highest temperature measured is the reported value. If it is unsafe to measure the extrudate temperature using a handheld device, then an IR temperature sensor is used to estimate the discharge temperature. 

The temperature of molten polymer process streams is commonly measured using a thermocouple positioned through a transfer line wall and partially immersed in the polymer stream. Process stream temperature measurements that use an exposed-tip thermocouple, however, can be misleading since the temperature of the thermocouple junction is a balance between the heat transferred from the polymer stream and from the thermocouple assembly [39]. Due to the low heat transfer rate between the polymer and the exposed tip and the high thermal conductivity of the thermocouple sheath, the temperatures measured can be different by up to 35°C depending on conditions. Extrudate temperatures, however, can be accurately measured using a preheated, handheld thermocouple probe. This method minimizes thermal conduction through the probe sheath. 

The discharge temperature should always be measured with a handheld temperature probe because it provides the most accurate measurement. Thermocouple sensors positioned through transfer lines and exposed to the melt stream do not provide an acceptable measurement of the discharge temperature due to the high... 

Instruments for Measuring Temperature and Humidity. These include one handheld Digital Pyrometer (Fisher 13-904-50) and one Thermocouple Probe (Fisher 13-904-50A or 13-904-50C). The probe provides a digital display of temperature, relative humidity (RH), and dew point. It is very accurate and reads and recalls the above parameters during long monitoring periods. 

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