The back connection thermometers and the bottom connection thermometers should be mounted at any convenient location where it will be subjected to the average temperature variations to be indicated. Avoid bending the stem as this will cause misalignment of the internal parts, resulting in undue frictional errors. To tighten the thermometer to the apparatus, use a wrench applied to the hexagon head of the threaded connection located just outside of the case.
Locate the stem so that at least two inches will be subjected to the average temperature to be measured. Exposing the stem to a temperature in excess of the highest dial reading should be avoided. The thermometer is normally provided with a threaded connection.To tighten the thermometer to the apparatus or into the well, use an open-end wrench applied to the hexagon head of the threaded connection.Turn until reasonably tight, then tighten still further in the same manner as a pipe elbow or similar pipe fitting until the scale is in the desired position for reading. Install the dry type thermometer so that the maximum case temperature is kept below 200°F at all times. Install the liquid filled type thermometer so that the maximum case temperature is kept below 150°F at all times. When a thermometer is equipped with a well, the well should be installed onto the apparatus first.The stem of the thermometer should then be coated with a heat conducting medium (a mixture of glycerin and graphite or vaseline or any other heavy lubricant may be used), after which the thermometer stem is inserted, and tightened into the well.
Thermowells should be used on all pressurized applications, to protect the thermometer from corrosion or physical damage, and to facilitate removal of the thermometer without disturbing the process.