Relating to valves and methods therefor

A valve to control flow of a fluid under pressure, comprising,

• A valve body with a first port, and a second port, to, in part, define a duct therebetween, to duct the flow of the fluid between the first port and the second port,
• A valve bonnet removably engaged to the valve body between the first port and the second port, to further define the duct, the valve bonnet having a valve end interior to the duct, and an opposing actuator end exterior to the duct,
• A valve member having an endless skirt at least in part controlled by a central stem within the duct from the valve bonnet, the endless skirt having an outer periphery, which the valve body defines an annular chamber about, and the endless skirt having an inner periphery which defines an inner chamber, the valve member having a closed position to prevent flow of fluid, and an open position to allow flow of fluid,
• The endless skirt, when in the closed position, sealing against the valve bonnet at a first effective sealing diameter, the endless skirt in co-axially moving supported engagement with the valve body or a part thereof, and
• the endless skirt in sealing engagement with an interior periphery of the annular chamber at a second effective sealing diameter,
• A plurality of passages in selective fluid communication between the annular chamber and inner chamber, which plurality of passages are progressively exposed as the valve member moves from the closed position to the open position, to allow fluid flow between annular chamber and the inner chamber,
• the central stem in co-axially moving supported engagement with the valve bonnet or part thereof and the central stem in sealing engagement with the valve bonnet at a third effective sealing diameter.