Aperflux 851 is one of the pilot-operated gas pressure regulators by Pietro Fiorentini. This device is suitable for use with previously filtered non-corrosive gases, and it is mainly used for high-pressure transmission systems and for medium pressure natural gas distribution networks. According to the European Standard EN 334, it is classified as Fail Open. Aperflux 851 is Hydrogen Ready for NG-H 2 blending.

The Aperval and Aperflux top entry regulators are available in 1”-10” sizes in ANSI 150# -900# rating in ductile iron and LCC steel body configurations with available outlet pressure ranges from 3-4” W.C -1054 psig. These regulators can be configured with patented noise silencer and optional high- and low-pressure slam shut module. Suitable applications would include commercial and industrial, city gate stations, compressor fuel gas as well a district regulator settings.