Water hammer-proof air valve and water hammer-proof exhaust method for in-use pipeline

A water hammer-proof exhaust method for a pipeline in-use, characterized in that, the water hammer-proof exhaust method comprises:

• a) the pipeline changes from an initial state into a water filling and exhaust state, a gas in the pipeline enters an inner cavity of a valve body through an inlet of the valve body, an airflow enters an upper part of the valve body through a ring cavity between the valve body and a casing, the airflow is then discharged to an outside atmosphere through an exhaust window of the casing, a bonnet opening of a bonnet, a flow surface between a throttle disc and a throttle tube, a sealing disc and a shield;
• b) as an exhaust rate keeps increasing, an exhaust pressure difference increases to a design value, the throttle disc is blown up by the airflow and blocks an exhaust opening of the throttle tube, leaving only an throttle orifice on the throttle disc for exhaust;
• c) as the gas in the pipeline is discharged, the exhaust rate and the exhaust pressure difference will gradually decrease, an airflow pushing force subjected by the throttle disc will also gradually decrease, when a dead-weight of the throttle disc is greater than the airflow pushing force, the throttle disc will fall to a bottom part of the throttle tube and returns to an initial location;
• at this moment, a water level rises, enters an inner cavity of the valve body, and drowns a floating ball and a sliding mass, the floating ball and the sliding mass float upward with the water level, a sealing face of the sliding mass contacts with a sealing ring, forming a sealing of an exhaust opening of the high-speed intake and exhaust device;
• an upper part of the floating ball contacts with a sealing face of the trace exhaust valve seat, forming a sealing of a trace exhaust opening;
• as a water pressure in the valve body increases, a seal specific pressure at a sealing part is increased, the valve closes, and neither water nor the gas can be discharged through the valve, realizing a sealing of the valve;
• d) after the valve closes, when the gas is separated out from the pipeline, the separated gas gradually gathers to the upper part of the valve body of the high-speed intake and exhaust device which is located at a high point of the pipeline;
• as the gathered air increases, an air pressure rises to exceed the water pressure, on one hand keeping the sliding mass staying in a sealing state, and on the other hand making the water level that drowns the floating ball fall, the floating ball falls with the water level and opens a sealing at a trace exhaust valve seat, and the trace exhaust valve seat starts to exhaust;
• when the gathered air pressure decreases, the water level rises, and the floating ball ascends with the water level and seals the trace exhaust valve seat again;
• and
• e) when the pipeline stops pumping, starts evacuating, or bursts, the water level in the air valve falls, an outside air pressure is greater than the water pressure in the pipeline, the sliding mass and the floating ball fall due to decreases of the water pressure and the water level, an intake and exhaust opening of the high-speed intake and exhaust device opens, and massive outside air is suctioned into the pipeline to eliminate vacuum in the pipeline.