Parker Hannifin Corporation, has introduced a new line of sensor assemblies, to protect temperature instruments from damage due to pressure and velocity in process systems, as well as viscous, abrasive, or corrosive materials.

The Thermowell Sensor Assemblies product consists of a connection head, spring fitting or nipple union nipple, resistance temperature detector (RTD) or thermocouple, and the thermowell.  Parker Texas thermowells are available in threaded, flanged, VanStone, socket weld, weld-in, and sanitary styles in other hard-to-find materials beyond stainless steel.

The assemblies offer two temperature sensor options – RTD or thermocouple.  RTDs and thermocouples are both used to measure temperature, but the two types of sensors vary in temperature range, tolerance, accuracy, interchangeability, and cost.

RTDs are temperature sensors that measure the predictable change in electrical resistance of materials with changing temperatures.  Due to their superior accuracy and repeatability as compared to thermocouples, RTDs are increasingly becoming the temperature sensors of choice.  RTDs must have an external power source to function.  A small current is passed across the element, and the voltage, which is proportional to resistance, is then measured and converted to units of temperature calibration.  RTDs use either wire wound or thin film elements with a reference resistance of 100 ohms at 32 F (0 C) and can be used in temperature ranges from -328 F to 1,112 F (-200 C to 600 C), depending on the elements used.

Depending on the type and material, thermocouples can be used in temperature ranges from -328 F to 2,300 F (-200 C to 1,260 C).  Parker Thermowell Sensor Assemblies utilize thermocouple types in the most common calibrations of J, K, T, and E.  

Connection heads and fittings complete the Parker Thermowell Sensor Assembly.  The connection heads are available in cast iron, aluminum, or 316 stainless steel.  They meet NEMA 4X requirements and provide a clean, protected area for a terminal block or transmitter.  The fittings are spring-loaded or nipple union nipple in stainless steel or carbon steel.