Diaphragm interface apparatus to improve a cycle life of a diaphragm are described. An example fluid regulator includes a fluid flow passageway between an inlet and an outlet, where a sensing chamber defines a portion of the fluid flow passageway. A diaphragm senses a pressure in the sensing chamber and a diaphragm interface adjacent the sensing chamber has a curved surface to contact a portion of the diaphragm that moves in response to pressure changes in the sensing chamber. The curved surface affects an amount of stress imparted to the portion of the diaphragm during operation of the fluid regulator.

An oscillating diaphragm valve is provided. The valve is configured such that, when the diaphragm is in a closed position, pressure of a fluid supply opens the valve, and when the diaphragm is in an open position, the pressure of the fluid closes the valve. The valve internals are formed as a single, enclosed piece, with openings provided only for supply and consumption. The pilot-operated diaphragm-type valve uses a return spring for the diaphragm that applies a biasing force to an outside surface of the valve internals. Additionally, an actuator is provided to selectively arrest the diaphragm in an open or closed position by applying force to a different outside surface of the valve internals.

A gas flow regulating device including a housing assembly, an inlet tube assembly, and a biasing device. The housing assembly has a main housing, a valve seat body, and a distal plate forming an outlet orifice. The inlet tube assembly includes a proximal inlet end, a tube forming a lumen, and a flange, and is slidably disposed within the main housing, biased to an open state by the biasing device. The flange separates middle and constant pressure chambers within the housing assembly. The inlet tube assembly is transitionable to a closed state in response to pressure in the constant pressure chamber to generate a relatively constant flow rate of air exiting the device via the outlet orifice.

A method and arrangement for maintaining fluid flow pressure in a system at a preset, almost constant level. One application is an impulse turbine's nozzle valve, which automatically maintains the system pressure essentially constant so that it does not depend on occasional variation of the pumped inflow, resulting that also the jet from the nozzle remains constant and its kinetic energy optimal. The nozzles independently maintain system pressure when the inflow varies.

A gas negative pressure valve is provided which comprises a valve body and a valve cover. A gas inlet and a gas outlet are disposed on the valve body. A drive lever and a diaphragm assembly are disposed inside the valve body, and one end of the drive lever is connected to a lower end of the diaphragm assembly, and the other end of the drive lever is connected with a sealing gasket. An end of the drive lever is hinged on a sidewall of the valve body. A reset spring is disposed between the drive lever and a bottom of an inner chamber of the valve body. A guide passage is opened in the inner chamber of the valve body. An end of the drive lever close to the gas inlet is connected with a guide shaft, a lower end of which is cooperated slidably in the guide passage.