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 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 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. <EOS>