Generally, sheathed type temperature sensors are used with thermowell. To maximize the heat-transfer between sheath junction and thermowell, the sheath must be inserted as close as possible to the bottom of the well. However, it is not always possible to determine the actual distance between the end tip of the sheath and the bottom of the thermowell. Furthemore, heat expansion can damage the sheath which is located inside the thermowell. To prevent this uncertainty and the damage to the sheath, RS series employ the spring load type sheath. This spring load absorbs the impact to the sheath, and protects the sheath from the vibration. Moreover, it is designed to be used in an explosive area.