Able to be used in existing unloader system or on its own as optimized alternative to traditional finger style and plug style unloaders, ZVI unloader valve can be serviced in field without additional machining. This piston-style unloader can be used in all brands of compressors, at any speed, for both lubricated and non-lubricated cylinders. Also, solution supports use with virtually any gas where max DP across unloader is up to 1,500 psi.