AIM Technology Inc.
Advanced Inprocess Monitoring Systems
Phone (215) 872-1692
Sheath Types Based on the application temperature range to be monitored, and the corrosive nature of the environment, a wide variety of protective sheath types are available. Choosing the proper sheath will protect the thermocouple, which will result in a temperature sensor which will be reproducible and have reliable and sustainable performance. Sheathed thermocouple probes are available with one of three junction types: grounded, ungrounded, or exposed.Grounded: At the tip of a grounded junction probe, the thermocouple wires are physically attached to the inside of the probe wall. This results in good heat transfer from the outside through the probe wall to the thermocouple junction. Ungrounded: In an ungrounded probe, the thermocouple junction is detached from the probe wall. Response time is slower than the grounded style, but the ungrounded offers electrical isolation. Sheath type depends on the instrumentation. If there is any chance that there may be a reference to ground (common in controllers with nonisolated inputs), then an ungrounded probe is required. If the instrument is a handheld meter, then a grounded probe can almost always be used.
Sheath Material Temperature Graph