The calibration points of elastic pressure gauge shall be evenly selected within the measuring range. In addition to the zero point, for the pressure gauge and vacuum gauge, the check points shall not be less than 4 points. For pressure vacuum (linked) gauge, the calibration points at pressure part shall not be less than 3 points. Those at vacuum parts shall be 1 ~ 3 points. Big scale with a digital points shall be generally selected for the check points.