Stepped opening diaphragm gas valve

Claim 1

In a stepped opening, fluid, pressure operated, gas valve, a valve body having an inlet, an outlet, and a main passageway connecting said inlet and outlet, a biased closed main valve controlling the flow through said passageway including a fluid pressure responsive actuator operative to move said valve openward when the fluid pressure is sufficiently higher on one side thereof than on the other, means providing communication between said inlet and said one side of said actuator, means providing relatively restricted communication between said inlet and said other side of said actuator, a bleed passage extending from said other side of said actuator to an area of relatively low pressure, a control valve in said bleed passage movable to open and close said bleed passage, flow limiting means in said bleed passage upstream from said control valve operative to limit the bleedoff rate when said control valve is open to that which will effect a predetermined partial opening of said main valve, a bypass passage around said flow limiting means, a pressure regulator valve controlling said bypass passage and which when operative permits a greater bleedoff rate and effects a further opening of said main valve, resilient means biasing said regulator valve closed, stronger opposed resilient means capable of opening said regulator valve when operatively connected thereto, fluid pressure responsive means operating between atmosphere and the pressure in said bleed passage when said control valve is closed to flex and space said stronger resilient means from operative connection with said regulator valve, and said fluid pressure responsive means having restricted communication with the atmosphere, thereby to delay its response to the pressure drop in said bleed passage to permit opening of said regulator valve following the opening of said control valve whereby a second greater flow step due to further opening of said main valve is delayed.