An intravenous catheter apparatus comprising: a catheter hub arranged at a proximal end of a catheter tube, the catheter hub having an inner surface defining a chamber; a needle defining an axial direction and having a needle tip, the needle extending through the chamber and the catheter tube when in a ready position; a needle guard slidably arranged on the needle and at least partially received in the chamber when the needle is in the ready position, the needle guard including a base portion and first and second arms (36, 38) extending from the base portion, wherein the first arm is deflected radially outwards by the needle against a restoring force when the needle is in the ready position whereby the needle guard is brought into retaining contact with the catheter hub; and wherein the intravenous catheter apparatus includes a valve (100 - 700) which separates a distal space arranged in distal direction from the valve (100 - 700) from a proximal space arranged in a proximal direction from the valve (100 - 700), wherein the valve (100 - 700) opens based on a pressure differential between the pressure prevailing in the distal space and the pressure prevailing in the proximal space, wherein the valve (100 - 700) comprises: a housing (101, 102; 201; 202; 201, 302; 401, 402) having a first opening (101a; 201a) and a second opening (102a; 202a); and an elastomeric member (110; 210) positioned in the housing (101, 102; 201; 202; 201, 302; 401, 402), the elastomeric member (110; 210) comprising a surface (167; 267), and a slit (117; 117a) extending through the surface (167; 267); characterized in that the elastomeric member (110; 210) comprises a continuous peripheral wall (169; 269) projecting from the surface (167; 267), a continuous portion of the peripheral wall (169; 269) creating a continuous sealable contact with the housing (101; 201; 401) and partitioning the housing (101, 102; 201; 202; 201, 302; 401, 402) into an upper section and a lower section, the elastomeric member (110; 210) configured such that upon creating a pressure differential between the upper section and the lower section of the housing (101, 102; 201; 202; 201, 302; 401, 402) causes either: (i) the peripheral wall (169; 269) to deflect from the housing (101; 201; 401) permitting fluid flow around the elastomeric member (110; 210); or (ii) the slit (117; 117a) to open permitting fluid flow through the elastomeric member (110; 210). a catheter hub arranged at a proximal end of a catheter tube, the catheter hub having an inner surface defining a chamber; a needle defining an axial direction and having a needle tip, the needle extending through the chamber and the catheter tube when in a ready position; a needle guard slidably arranged on the needle and at least partially received in the chamber when the needle is in the ready position, the needle guard including a base portion and first and second arms (36, 38) extending from the base portion, wherein the first arm is deflected radially outwards by the needle against a restoring force when the needle is in the ready position whereby the needle guard is brought into retaining contact with the catheter hub; and wherein the intravenous catheter apparatus includes a valve (100 - 700) which separates a distal space arranged in distal direction from the valve (100 - 700) from a proximal space arranged in a proximal direction from the valve (100 - 700), wherein the valve (100 - 700) opens based on a pressure differential between the pressure prevailing in the distal space and the pressure prevailing in the proximal space, wherein the valve (100 - 700) comprises: a housing (101, 102; 201; 202; 201, 302; 401, 402) having a first opening (101a; 201a) and a second opening (102a; 202a); and an elastomeric member (110; 210) positioned in the housing (101, 102; 201; 202; 201, 302; 401, 402), the elastomeric member (110; 210) comprising a surface (167; 267), and a slit (117; 117a) extending through the surface (167; 267); a housing (101, 102; 201; 202; 201, 302; 401, 402) having a first opening (101a; 201a) and a second opening (102a; 202a); and an elastomeric member (110; 210) positioned in the housing (101, 102; 201; 202; 201, 302; 401, 402), the elastomeric member (110; 210) comprising a surface (167; 267), and a slit (117; 117a) extending through the surface (167; 267); characterized in that the elastomeric member (110; 210) comprises a continuous peripheral wall (169; 269) projecting from the surface (167; 267), a continuous portion of the peripheral wall (169; 269) creating a continuous sealable contact with the housing (101; 201; 401) and partitioning the housing (101, 102; 201; 202; 201, 302; 401, 402) into an upper section and a lower section, the elastomeric member (110; 210) configured such that upon creating a pressure differential between the upper section and the lower section of the housing (101, 102; 201; 202; 201, 302; 401, 402) causes either: (i) the peripheral wall (169; 269) to deflect from the housing (101; 201; 401) permitting fluid flow around the elastomeric member (110; 210); or (ii) the slit (117; 117a) to open permitting fluid flow through the elastomeric member (110; 210). (i) the peripheral wall (169; 269) to deflect from the housing (101; 201; 401) permitting fluid flow around the elastomeric member (110; 210); or (ii) the slit (117; 117a) to open permitting fluid flow through the elastomeric member (110; 210).