Device for controlling fluid flow

A device for controlling the flow of a fluid through a conduit from an upstream side of the device to a downstream side of the device, the device comprising:

• a cylindrical valve aperture;
• a cylindrical mounting member arranged on a downstream side of the cylindrical valve aperture;
• a valve member movably mounted on an outside of the cylindrical mounting member and arranged to move reciprocally relative to the cylindrical mounting member to selectively open and close the valve aperture, thereby controlling flow of the fluid through the valve aperture, wherein the valve member comprises a planar end that is arranged to extend fully over, and fit into, an area of the cylindrical valve aperture;
• a control volume defined between the cylindrical mounting member and the cylindrical valve member;
• and
• a control conduit for introducing the control pressure into the control volume;
• wherein the valve member is acted on by a pressure of the upstream side and the control pressure so as to be moved by a difference between these pressures.

A device for controlling the flow of a fluid through a conduit from an upstream side of the device to a downstream side of the device, the device comprising:

• a valve aperture;
• a cylindrical mounting member arranged on a downstream side of the valve aperture;
• a valve member movably mounted on an outside of the cylindrical mounting member and arranged to move reciprocally to selectively open and close the valve aperture, thereby controlling flow of the fluid through the valve aperture;
• a control volume arranged to receive a control pressure for acting on the valve member, wherein the device comprises no more than one control volume for receiving the control pressure that acts on the valve member, and wherein the control volume is defined between the cylindrical mounting member and the valve member;
• and
• a control conduit for introducing the control pressure into the control volume, wherein the control conduit is fluidly connected to a control pressure regulator for introducing and controlling the control pressure in the control volume;
• wherein the valve member is acted on by a pressure of the upstream side and the control pressure so as to be moved by a difference between these pressures, and wherein the control pressure regulator is in fluid communication with the upstream side of the device and arranged to set the control pressure dependent on the upstream pressure.