A disposable set 5 for establishing a fluid connection between a fluid dispensing unit 17 forming a reusable fixed of the fluid dispensing system and a dosing device adapted to dispense the fluid into a patients&rsquo； vein. The disposable set comprises a length of a tubing 15 for establishing a fluid connection from the fluid dispensing unit towards and into the dosing device. The tubing 15 comprise a first and a second tube, the first tube 1 being provided to establish at a first end 4 a connection to a second end 9 of the second tube 10, and at a second end 14 a connection towards the fluid dispensing unit. The second tube 10 is provided to establish at a first end 6 a connection towards the dosing device and the patient and at a second end 9 a connection to the first tube 1. The first tube 1 comprises a first one-way valve 3 which is provided to permit a fluid flow from the dispensing unit 17, 18 towards the dosing device and to prevent a backward fluid flow from the dosing device towards the fluid dispensing unit. The first end 4 of the first tube and the second end 9 of the second tube 10 are in fluid connection with each other in a liquid tight manner by means of a releasable connection device 11, 12. The releasable connection is adapted to permit backflow from the patient into the second tube 10 in the direction of the releasable connection device in the released position of the releasable connection and to prevent a backflow from the patient in the direction of the releasable connection device 11, 12 in the closed position of the releasable connection. The releasable connection device comprises a first 11 and a second connector 12. The second connector 12 is fastened to a second end 9 of the second tube 10. The first connector 11 is mounted to an outlet side 2 of the first one-way valve 3, to permit a fluid flow from the fluid dispensing unit through the first one-way valve 3 into the second tube 10 when the first 11 and second connector 12 have been engage
