![]() 4 Viscosity, which was measured in the ns range from 6.5 to 45 rpm and at viscosities of up to νz = 4000 Was measured only at ns = 15 to 20 rpm and, in this narrow application range, leads to similar results to the KSB technique see Fig. Both techniques use diagrams to illustrate the conversion factors, which - though they are used in a similar way - differ in that the KSB technique includes the influencing variables Q, H and ν as well as being clearly influenced by the specific rotational speed ns in addition. The two most well-known techniques are those according to the Standards of the Hydraulic Institute (HI) and according to KSB. Ν > 20 ♱0 –6 m 2/s and must be converted using empirically calculated conversion factors only after this limit is reached. The characteristic curves of centrifugal pumps show noticeable effects only at a kinematic viscosity of falling sphere and flow measuring methods.Įffect on the characteristic curves of pumps Viscometry also includes other processes, e.g. ![]() Drive torque, circumferential speed, the size of the wetted cylinder surface and the wall clearance in the pot are measured at several rotational speeds. 2 Viscosityĭynamic viscosity η can be measured for all liquids using a rotational viscometer, in order to record the viscosity curve, as follows: a cylinder with freely^selectable rotational speed rotates in a cylindrical pot filled with the liquid to be tested. 1 ViscosityĪs the temperature increases, almost all liquids become thinner, i.e. The dependence of kinematic viscosity ν on temperature t is shown both for water,Īnd for mineral oil distillates with the axes being partitioned in such a way as to provide straight lines. The SI unit for kinematic viscosity, on the other hand, contains only kinematic dimensions for length (m) and time (s). The term "dynamic viscosity" is derived from the Greek "dynamis", which means force, since the SI unit contains a unit of force (N). The SI unit of dynamic viscosity is Ns/m 2 = Pas, the SI unit of kinematic viscosity is m²/s. However, in practice it is normal to specify the viscosity-density ratio ( kinematic viscosity). 1 Pulp pumping. All other curves denote non-NEWTONian liquids handled in Pulp pumping applications, whose effects on the operation of centrifugal pumps cannot easily be calculated by the usual methods. ![]() The viscosity curve in the shear stress diagram (τ = f(∂vx/∂y)) is, therefore, a line through the origin, see Fig. The physical definition of viscosity originates in the NEWTONian formulation of shear stress ( NEWTONian liquid). It is necessary to differentiate between dynamic and kinematic viscosity. Viscosity is the property of a fluid, to resist the relative displacement of adjoining layers (internal friction). ![]()
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