Electronic Triple Point Cell.

An electronic triple point calibration system comprising in combination triple-point-of-water cells provided with means for sealing a central thermowell provided in the heat conducting fixture for inserting thermometer being calibrated a temperature probe installed on heat conducting fixture and a housing for enclosing the heat conducting fixture and intimately mounted cells in a mounted combination. The cells are prepared from glass, polytetrafluoroethylene, or other material which does not react with water. After thoroughly cleaning, the cells are partially filled with pure water and vacuum sealed. A plurality of cells are intimately mounted on the heat conducting feature designed to accommodate the outer contours of the cells equally spaced around the central thermowell. The mounted combination with cells installed is frozen prior to testing. The electronic triple point calibration system temperature probe during testing is connected to measuring means for measuring millivolt output equivalent to temperature values in determining the triple-point-of-water temperature. The electronic triple point calibration system further comprises for automated operation a DC control system electrically connected to the temperature probe, a DC switching means for receiving millivolts output, from the temperature probe, and refrigeration means including control system for freeze control with operational circuitry including associated DC switches, relays, and contacts for generating and maintaining the triple-point-of water temperature in the central thermowell.