The principle of the piston type filling machine, using pneumatic components to replace the electrical control circuit, and the mechanical stroke location, so the precision ratio design based on original electrical models combined with the launch on a new generation of products, it adopts pneumatic components to replace the electrical control circuit, so it is particularly suitable for use in explosion-proof environment in. The piston is made of polytetrafluoroethylene. All 304 materials are in contact with the material.