from the surface can be communicated through the bore of the tubing string 14 to the fluid chamber 128 and applied to the area formed between the o ring seal 124 and the inner diameter of the operator mandrel 114 the bottom surface 142 of a flange portion 126 of the power mandrel 122 initially sits on a shoulder 150 of a protruding section 156 of a spline sleeve 152 if the fluid chamber pressure exceeds the reference pressure of the gas chamber 110 then the power mandrel is pushed up or to the left of the page on fig5 b the power mandrel 122 can travel the distance defined by a gap 146 until the top surface 148 of a flange portion 126 bumps up against the bottom face 134 of the first housing section 112 an o ring seal 124 prevents fluid communication between the fluid chamber 128 and the gas chamber 110 and an o ring seal 144 prevents fluid communication from outside the housing of the fiv 18 when the power mandrel 122 is pushed to its up position half a power cycle has occurred when fluid pressure in the fiv bore 108 is next bled off at the surface until the gas chamber reference pressure exceeds the fluid chamber pressure the power mandrel 122 drops back down until the bottom surface 142 of a flange portion 126 hits the shoulder 150 defined by a protruding section 156 of the spline sleeve 152 each up and down motion of the power mandrel 122 defines one cycle of the counter section 200 after a predetermined number of cycles the counter section 200 of the fiv 18 is activated to allow the power mandrel 122 to move down past a protruding section 156 of the spline sleeve.