FREE-VALVE’s A28H spring full bore external thread type with lever safety valve(thread type) is based on the change of the media pressure at the inlet port and the spring pretension force to automatically open and close the valve disc.When the lifting force of the medium pressure (internal pressure) is higher than the spring pretension force, The valve disc overcomes the spring pretension force to open automatically, and the safety valve internal pressure drops after discharging excess media
