A safety device for occluding a flow through a vascular access system, the safety device comprising: a casing having an inlet port and an outlet port; a fluid pathway in communication with the inlet port and the outlet port; and an occlusion valve interposed between the inlet port and the outlet port, comprising a compression chamber with an upper chamber and a lower chamber, whereby the chamber (90, 100) are defined by a plunger slideably positioned within the compression chamber, the occlusion valve having a threshold pressure, wherein a fluid pressure within the fluid pathway that exceeds the threshold pressure activates the occlusion valve to occlude the fluid pathway, wherein the occlusion valve comprises a piston fixedly coupled to the plunger, whereby the piston comprises a first, a second end and a middle portion supporting the plunger, the first end being entirely positioned within the upper chamber and being slidably in the upper chamber, and the second end being slidably positioned in the lower chamber, the second end of the piston extends from the plunger through the lower chamber into the fluid path, wherein upon activation of the occlusion valve, the piston translates within the compression chamber to an activated position whereby the second end of the piston occludes the fluid pathway, characterized by a hook feature forming a terminal end portion of the piston, and a stepped surface forming a terminal end portion of an inner wall surface of the compression chamber, wherein upon activation of the occlusion valve, the hook feature and the stepped surface interlock and retain the piston in the activated position, thereby preventing further infusion. a casing having an inlet port and an outlet port; a fluid pathway in communication with the inlet port and the outlet port; and an occlusion valve interposed between the inlet port and the outlet port, comprising a compression chamber with an upper chamber and a lower chamber, whereby the chamber (90, 100) are defined by a plunger slideably positioned within the compression chamber, the occlusion valve having a threshold pressure, wherein a fluid pressure within the fluid pathway that exceeds the threshold pressure activates the occlusion valve to occlude the fluid pathway, wherein the occlusion valve comprises a piston fixedly coupled to the plunger, whereby the piston comprises a first, a second end and a middle portion supporting the plunger, the first end being entirely positioned within the upper chamber and being slidably in the upper chamber, and the second end being slidably positioned in the lower chamber, the second end of the piston extends from the plunger through the lower chamber into the fluid path, wherein upon activation of the occlusion valve, the piston translates within the compression chamber to an activated position whereby the second end of the piston occludes the fluid pathway, characterized by a hook feature forming a terminal end portion of the piston, and a stepped surface forming a terminal end portion of an inner wall surface of the compression chamber, wherein upon activation of the occlusion valve, the hook feature and the stepped surface interlock and retain the piston in the activated position, thereby preventing further infusion.