The quality of the stainless steel eccentric head should meet the current national standard. The deviation should be in accordance with the provisions of table 4.2-3. Stainless steel eccentric reducer should not have crack, double skin appearance, wall thickness should be greater than the big diameter end section of the wall thickness, roundness eccentric reducer stainless steel shall not be greater than 1% of the corresponding end diameter, and the allowable deviation of plus or minus 3 mm; The center line of the concentric reducer should coincide, and its eccentricity should allow the deviation to be plus or minus 5mm. Size head if choose diameter specification does not accord with the inner diameter of the process piping, should undertake the corresponding reducing or expanding process, if the shrink tube, pipe pressure loss caused by this should be considered whether affect the process. In order to prevent the installation of reducer influence the distribution of velocity field, pressure loss, and reduce the measurement accuracy of electromagnetic flowmeter, the requirements of the central Angle alpha is not more than 15 °, as small as possible. There are two kinds of concentric and eccentric, the concentric size head is commonly used in vertical tube; The stainless steel eccentric head is used for horizontal pipe and should be noted to indicate the top or bottom.