Patent ID: 10613009

Abstract:
In a measuring method for measuring the viscosity of an essentially non-compressible measuring medium (F) with a measuring device (1) comprising a first container (2), wherein the measuring medium (F) can leak from the first container (2) via a capillary (11) which, in an operating position, is arranged at a certain capillary angle (α) toward the horizontal, preferably perpendicularly, via an outlet opening (13) of the capillary (11), the measuring medium (F) is introduced, in a first process step, into the first container (2) filled with a compressible medium, in particular ambient air (L), whereupon the measuring medium (F) occupies a partial volume (VF0) of the total volume (V0) of the first container (2), wherein, in a second process step, a first pressure difference (Δp1), which is kept constant, and, respectively, a second pressure difference (Δp2), which is kept constant, or a pressure difference Δp(t)), which decreases over time, are adjusted between a pressure (p1 or, respectively, p2; p(t)) of the compressible medium (L) in the first container (2) and a pressure (p0) of the compressible medium (L) at the outlet opening (13) of the capillary (11), wherein, in a third process step, the decrease in volume (dVF(t)/dt) of the measuring medium (F) per time unit is determined for the first pressure difference (Δp1), which is kept constant, and the second pressure difference (Δp2), which is kept constant, or for a first pressure difference (Δp(t)), which decreases as a result of the decrease in volume (dVF(t)/dt) of the measuring medium (F), in order to determine at least two measurement points of the decrease in volume (dVF(t)/dt) of the measuring medium (F) per time unit over the pressure difference (Δp) as a resulting straight line (14) in a coordinate system, wherein, in a final process step, the kinematic viscosity (ν) is determined from the value (15) of the resulting straight line (14) for the decrease in volume (dVF(t)/dt) of the measuring medium (F) per time unit at the pressure difference of Δp=0 and the dynamic viscosity (η) of the measuring medium (F) is determined from the slope of the resulting straight line (14).