The full form of EVRV is Electronic Vacuum Regulator Valve

The Model 487 Electronic Vacuum Regulator is designed to accept a user’s analog control signal generated from a user’s electronic system or potentiometer to adjust the set point of the vacuum regulator. Additionally the unit can be configured to operate as an electronic pressure regulator.  Jumper settings on the regulator board allow the user to select the control signal type: external potentiometer, on-board potentiometer or external analog signal up to 5 volts. Two ranges of pressure sensors are available 487-001 (0 to 41 inches of water, 3 in-Hg, 1.5 psi) or 487-002 (0 to 29.5 in-Hg, 760 in-Hg approx. 14.5 psi). Both models are atmospheric pressure referenced, which means their output will be constant relative to the atmospheric pressure. An absolute pressure reference sensing version is available. Two different flow range versions are available for either model regulator. The smallest flow range valve that meets the application’s flow requirements should be selected to provide maximum control and resolution. These regulators are also capable of regulating positive pressure up to the same range as specified in vacuum. This regulator is self-relieving, meaning that it will follow a control signal as it is increased or decreased without the need to introduce a leak source or any additional valves to vent vacuum or pressure to obtain the new set point.