Calibration suspension unit, method for the manufacture of a calibration suspension unit and use of a calibration suspension unit

1. A calibration suspension unit comprising a container that is filled with a calibration suspension for the calibration of a turbidity meter, wherein the calibration suspension is a suspension of particles selected from the group consisting of formazine, styrene divinyl benzene, latex or metal oxide gel in a liquid, and wherein the container is made of a flexible material, and wherein there exists no air supernatant above the calibration suspension in the container.

2. The calibration suspension unit according to claim 1 , wherein the container is a foil bag.

3. The calibration suspension unit according to claim 1 , wherein the container has a wall having a thickness of less than 1 mm.

4. The calibration suspension unit according to claim 1 , wherein the container is air-tight and impermeable to liquids.

5. The calibration suspension unit according to claim 1 , wherein the container is impermeable to light.

6. The calibration suspension unit according to claim 1 , wherein the container is made of at least one of a plastic film and a metal foil.

7. The calibration suspension unit according to claim 1 , wherein a maximum volume of the container is larger than a volume of the calibration suspension in the container.

8. The calibration suspension unit according to claim 1 , wherein the calibration suspension unit comprises a hose line system, the hose line system comprising a hose line directly connected to the flexible container.

9. The calibration suspension unit according to claim 1 , wherein the calibration suspension unit comprises a hose line system, the hose line system comprising a hose line and a cannula provided at the hose line.

10. The calibration suspension unit according to claim 9 , wherein the container is closed by a septum lid.

11. The calibration suspension unit according to claim 8 , wherein the hose line has an internal diameter d2 and optionally the cannula has an internal diameter d1 of 9 mm at the most, preferably from 3 to 7 mm.

12. A method for manufacturing of a calibration suspension unit according to claim 1 , comprising the steps of:

a) providing a container made of a flexible material and a calibration suspension wherein the calibration suspension is a suspension of particles selected from the group consisting of formazine, styrene divinyl benzene, latex or metal oxide gel in a liquid;

b) filling the calibration suspension into the container,

c) removing substantially all air from the container, and

d) closing the container,

wherein there is no air supernatant above the calibration suspension in the closed container.

13. The method according to claim 12 , wherein the air is removed by mechanical compression of the container.

14. A method of calibrating a turbidity meter using a calibration suspension unit according to claim 1 , wherein the calibration suspension is introduced into the turbidity meter without substantial air bubble formation.

15. The method according to claim 14 , wherein the calibration suspension is mixed by mechanical deformation of the calibration suspension unit.

16. The method of claim 14 , wherein the calibration suspension is introduced into the turbidity meter by means of a hose line, wherein the flexible container collapses as the calibration suspension escapes from the container without air being drawn in as a volume compensation for the calibration suspension, and wherein all air in the hose line is displaced by the calibration suspension without forming of any air bubbles in the calibration suspension.

17. The calibration suspension unit of claim 7 , wherein a ratio of the volume of the calibration suspension to the maximum volume of the container is from 0.2 to 0.8.

18. The calibration suspension unit of claim 8 , wherein the hose line is detachably connected to the flexible container.