Auto-drain adopts aluminum mold, inside with stainless steel ball.When the buoyancy is lower thn the weight of ball and the compress air pressure, the drain mouth will close, but when the buoyancy and the ball rises, the mouth automatically opens. The housing of 160b auto-drainer adopts aluminum alloy mold and the surface plastic spraing solidified.The inner and outer sides have a corrosion resistance to the synthetic lubricant of compress machine.The strongpoins are reliable non-noisy, non-compress air loss, outlet aperture is not plug easily. The largest mission capacity can reach 800l/s. Packed in carton box