Buit-in parallel－connected electromagnetic pilot valve control, advanced craft and reliable action，diaphragm of main valve has capability of anti-corrosion and resisting -40 ℃ low temperature，Special stainless steel magnetic material never rusts or generates remanent magnetism，Class F loop with good insulation，When main valve shuts off, work pressure 0.3~0.4MPa,flow rate is 3-4.5Lmin。