Temperature controller using detector and transmitter - employs compensation and operated by liquid dilation

摘要

Errors in the indication or regulating action of temperature detector and transmitter using the expansion of liquid arise due to ambient temperature effects. These may be reduced by applying compensation. A temperature detector (10) is connected to one of a group (11) of transmitters by a capillary tube (17). The transmitter comprises a principal transmitter comprises a cylindrical body (13a) with a chamber (15) at one end into which the capillary tube is connected. The chamber contains a bellows (18) which reacts to changes of temperature to move a shaft (20). This bellows acts against a second compensating bellows (22). It consists of two concentric elements (22a, 22b) with the space (23) filled with liquid whose volume varies with ambient temperature.