The internationally recognized European Standard is EN 589. In the United States, tetrahydrothiophene (thiophane) or amyl mercaptan are also approved odorants, although neither is currently being utilized. An LPG regulator is a device that maintains a stable downstream pressure regardless of changes in gas flow and upstream pressure. Among them, the LPG jumbo regulator and the LPG quick-on regulator are typical representatives. http://www.peakgasregulator.com/gas-regulator/lpg-jumbo-regulator/