Designed for use with large LP-Gas and NH3 stationary storage container applications with 4”- 300# ANSI flanged openings. The pilot valve-controlled relief mechanism allows for precision start to discharge set points in conjunction with the high flow angled seat design for high relief flow capacity in a simplified design which eliminates the need for traditional external pressure relief valves. The dual pilot valve design allows for the change of either pilot valve without taking the storage container out of service, significantly reducing cost of future service and replacement. The relief port is designed with a 4" FNPT threaded outlet, allowing convenient discharge pipeaway if necessary.