1, first observe the dial of the thermohygrometer, find the selection key and adjustment button.
2, and then press the selection key to switch to the adjustment mode, and the parameter adjustment to zero, this time the pointer is located in the negative 0.00 or 0 scale position.
3, and finally place the thermohygrometer in the same environment as the standard or calibrated thermohygrometer, and keep it for half an hour to three hours.