... up and down,relying on this role and the check valve linkage back and forth to pump fluid ... it's full-enclosed design,will not leak.In the rare precious metal smelting,toxic,harmful,corrosive ... movement is only part of the diaphragm and check valve in the valve ball,so the maintenance,inspection is ... for pneumatic single diaphragm pump ODS series,pump and check valve of the body of cast iron,lined ...