An apparatus for checking a need for maintenance of a viscometer measuring consistency of suspension comprises a rigid rod and an elongated cavity in a measuring arm of the viscometer. The rigid rod is matched with the cavity for the rod to be movable in the cavity. The cavity is configured to become mismatched with respect to the rod in response to a bending of the measuring arm, the mismatch indicating a need for maintenance of the viscometer.

Aspects of the disclosure relate to clotting time tests detect clotting time based on the viscosity changes of a fluid sample, using a disk dropped within a test chamber containing the fluid sample from a disk maximal position to a disk minimal position, which is a point at which the disk settles within the fluid sample. Changes in the disk minimal position as multiple test cycles are conducted are used in assessing formation of a clot within the fluid sample. Methods of assessing such changes in the disk minimal position are disclosed.

An apparatus for checking a need for maintenance of a viscometer measuring consistency of suspension comprises a rigid rod and an elongated cavity in a measuring arm of the viscometer. The rigid rod is matched with the cavity for the rod to be movable in the cavity. The cavity is configured to become mismatched with respect to the rod in response to a bending of the measuring arm, the mismatch indicating a need for maintenance of the viscometer.

Aspects of the disclosure relate to clotting time tests detect clotting time based on the viscosity changes of a fluid sample, using a disk dropped within a test chamber containing the fluid sample from a disk maximal position to a disk minimal position, which is a point at which the disk settles within the fluid sample. Changes in the disk minimal position as multiple test cycles are conducted are used in assessing formation of a clot within the fluid sample. Methods of assessing such changes in the disk minimal position are disclosed.