The viscosity of a fluid measured at the shear rate specified by API. In the Bingham plastic rheology model, apparent viscosity (AV) is one-half of the dial reading at 600 rpm (1022 sec-1 shear rate) using a direct-indicating, rotational viscometer. For example, a 600-rpm dial reading is 50 and the AV is 50/2, or 25 cp.

Related Terms:

yield point