An 850 MPa type internally-heated gas pressure vessel, which adopts a double-stage compression system, was newly installed at the Tokyo Institute of Technology. At second compressing stage of this instrument, pressure gauge is difficult to use and pressure is estimated from the loaded oil pressure. In order to acquire reliable pressure conditions, a manganin string was placed in the sample chamber and its electrical resistance was measured as a pressure sensor. By using this technique, uncertainty of pressure value for the sample chamber is decreased to a few MPa.
