Abstract: An apparatus for lengthening an extendible pipe comprised of first and second pipe portions having an interior includes a cylinder having an end wall and an open end connected to the first pipe portion. A piston is received in slidable and sealable engagement with the cylinder and is connected to the second pipe portion. The piston, cylinder and end wall define a chamber that is physically isolated from the interior of the pipe. Introduction of a control fluid into the chamber displaces the piston relative to the cylinder so as to lengthen the pipe. The apparatus above may be applied to a sprinkler head riser apparatus and buried as part of an in-ground sprinkler system.

Abstract: An apparatus for changing a length of a pipe, the pipe including first and second pipe portions each having an interior, includes a cylinder having a first end wall and an open end, the cylinder being connectable to the first pipe portion. The apparatus also includes a piston having a second end wall, the piston being receivable in slidable and sealable engagement with the cylinder, the piston being connectable to the second pipe portion, wherein the cylinder and the second end wall define a chamber physically isolated from the interiors of the first and second pipe portions, the chamber being adapted to receive a control fluid for displacing the piston relative to the cylinder to vary a distance between the first and second pipe portions while permitting fluid communication between the first and second pipe portions, the chamber including a cushioning region in communication with the chamber.

Abstract: An apparatus for changing a length of a pipe, the pipe including first and second pipe portions each having an interior, includes a cylinder having a first end wall and an open end, the cylinder being connectable to the first pipe portion. The apparatus also includes a piston having a second end wall, the piston being receivable in slidable and sealable engagement with the cylinder, the piston being connectable to the second pipe portion, wherein the cylinder and the second end wall define a chamber physically isolated from the interiors of the first and second pipe portions, the chamber being adapted to receive a control fluid for displacing the piston relative to the cylinder to vary a distance between the first and second pipe portions while permitting fluid communication between the first and second pipe portions, the chamber including a cushioning region in communication with the chamber.

Abstract: An apparatus for lengthening an extendible pipe comprised of first and second pipe portions having an interior includes a cylinder having an end wall and an open end connected to the first pipe portion. A piston is received in slidable and sealable engagement with the cylinder and is connected to the second pipe portion. The piston, cylinder and end wall define a chamber that is physically isolated from the interior of the pipe. Introduction of a control fluid into the chamber displaces the piston relative to the cylinder so as to lengthen the pipe. The apparatus above may be applied to a sprinkler head riser apparatus and buried as part of an in-ground sprinkler system.