Method of precision temperature control using flowing water

A high‐precision temperature control method using flowing water near room temperature is described in this paper. The temperature of a thermostatic cell immersed in a water flow within a water jacket is regulated by controlling the temperature of the water circulating through the jacket. This control is accomplished by three‐step controlled heating and constant cooling. The method provides control with a short response time. Temperature stabilization‐process control within a fluctuation of ±25 μK over a period of 12 h and temperature variation‐process control at a rate of 320 μK/h with a fluctuation of less than ±50 μK are achieved. All of the electric devices for controlling and measuring, as well as the thermostatic cell, are placed in thermostatic containers the temperature of which is controlled within a fluctuation of ±0.05 K. The total error in these temperature measurements is estimated to be approximately ±11 μK.