Field Installation of Temperature Sensor Assemblies - Bulletin 60270 pages

Field Installation of Thermocouple & RTD Temperature Sensor Assemblies
Although temperature sensor buyers usually pay close attention to choosing the right device for the job, they are often less deligent when it comes to installation
Preparation
Before beginning the actual installation, you need to consider a number of factors. Will a thermowell be used? Do you have the appropriate type of wire and terminal head for your needs? The following advice might make the difference between a system that works and one that fails.
Validating Thermowell Size
Thermowells are often used to protect the sensor from abrasive materials in the environment, such as sand, coal dust, cement and other fine powders; or gases and fluids, such as water, steam and liquid chemicals, that may be under high flow rates. Thermowells are also used as the medium to withstand high pressures.
The size of the thermowell will have ideally been given due consideration before you buy the temperature sensor, but if you have not personally specified the parts, it is always a
good idea to check the immersion depth before beginning your installation. To do so, take a piece of wire smaller than the bore of the thermowell and insert it into the thermowell until it bottoms. Mark the wire even with the opening of the thermowell. Extract the wire and measure this length, X.
Now determine the female conduit thread of the thermowell. This will probably be 1/2” or 3/4” NPT. Allow a 0.50” engagement for a 1/2” NPT thread and 0.54” for a 3/4” NPT thread. When you subtract the engagement length from X, the length of your wire, the result, Y, will be the optimum sheath length from the end of the mounting thread to its tip. If your thermocouple/RTD sheath length is shorter, it will fit, but you must decide if the length is best for your application. If Y is larger, it would not be a good idea to install the thermocouple/RTD in this thermowell.
details. The very best sensor can perform poorly if it is not correctly installed. Let’s take a look at the right way to deploy thermocouple and RTD sensor assemblies, along with some of the preparation that will ensure a successful operation.
Thermocouple configurations include the RTD/Thermocouple assembly with a nipple-union-nipple mounting (above) and with an adjustable packing gland mounting (below).
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