A nephelometric process turbidimeter for measuring a turbidity of a liquid sample includes a transparent sample vial which comprises a sample vial lateral inner surface. A vial head comprises a vial head lateral inner surface. The vial head and the sample vial together define a sample volume of a liquid sample having a shape of a cylinder. A sample inlet opening is arranged at the vial head and comprises an inlet opening axis. A sample outlet opening is arranged at the cylindrical vial head lateral inner surface to be axially closer to the sample vial than to the sample outlet opening. The inlet opening axis is inclined with respect to an inlet cross plane with an inclination angle of 10° to 80°, and is angled with respect to a radius line from a middle of the cylinder to the sample inlet opening with a tangency angle of more than 15°.