Northman北部精机,比例溢流调速阀EFRD-G03-160-2-6-31,EFRD-G03-160-2-5-31,EFRD-G03-250-3-6-31,EFRD-G03-250-3-5-31,EFRD-G06-160-2-6-31,EFRD-G06-160-2-5-31,EFRD-G06-250-2-5-31,EFRD-G06-250-3-6-31,EFRD-G06-250-3-5-31