Archer Instruments manufactures five different models of Vacuum Regulators, for use in vacuum-feed gas chlorination systems and gas sulfur dioxide systems. The primary function of a Vacuum Regulator is to serve as a normally closed, diaphragm operated inlet valve for the vacuum system. The inlet of the Vacuum Regulator is connected to the pressurized gas source, while the outlet is connected to the rest of the vacuum feed system. When vacuum is applied to the regulator, the internal diaphragm acts upon and unseats the spring-loaded inlet safety valve, allowing gas to enter the system under vacuum. If the operating vacuum is lost for any reason, the spring-loaded inlet safety valve shuts to prevent any pressurized gas from entering the system.