... supply,exhaust system,and one-way valve.It's a use of air pressure to diaphragm moves up and down,relying on this ... protection.Because it's full-enclosed design,will not leak.In the rare precious metal smelting,toxic,harmful,corrosive and strong ... no rotating parts,so in the course of transmission fluid pump does not undermine the material in the crystallization of floc. 4. Fully sealed ...