This 3/4" vacuum relief valve is suitable for low pressure steam and water service. It can be mounted in-line in a horizontal or vertical position and is ideal for use in domestic water heaters and supply tanks. This valve automatically allows air to enter into the piping system to prevent vacuum conditions that could siphon water from the system and damage water equipment. It consists of a brass body, 3/4" male NPT connection, and a protective cap. The maximum steam working pressure is 15 psi (103 kPa).