Excess flow valve is used in pipeline installations and plants, gas lines, as well as for installation on pressure vessels, in order to prevent the flow of fluid from overflowing. The common use is for the installations for propane-butane, with maximum operating pressure 16.7 bar. It is made in variants A and B (for DN15 ÷ DN250) and variants C (for DN25 ÷ DN125). All three variants are partially ratified by construction and serve for the same purpose but adapted for different types of installation.