Safety valves for gas pipes, namely reverse flow check valves; regulation and safety accessories for gas installations, namely, pressure regulators for gas installations; stop valves, namely, reverse flow check valves for regulating gas; stop valves, namely, reverse flow check valves being safety apparatus for gas apparatus; gas regulators; pressure couplings for regulating gas, namely, gas regulators; IOT (internet of things), namely, gas regulators that may be monitored via the Internet