Abstract: A device for measuring the streaming potential of fibers and particles in suspensions, in particular a device for determining the zeta-potential of the particles of aqueous suspensions containing fibers and particles, by measuring the streaming potential, and by subsequently computing the zeta-potential with an empirical formula. A periodic pressure curve is generated by arranging in the device for measuring the streaming potential at least two vacuum vessels, with each vessel having a different constant reduced pressure. The vacuum vessels are permanently set to a different vacuum and alternatingly connected via a valve to the measurement cell with the fiber plug. The required reduced pressure in the two vacuum vessels is maintained by using at least one small, low-capacity vacuum pump and a valve controller.

Abstract: The invention relates to an apparatus and a method for determining the softness of a hygienic paper or textile with at least one ply, wherein an element (106) is arranged relative to a positionally fixed sample (P), with at least one ply, of the hygienic paper or textile such that it can move and is designed such that it can be adjusted with respect to the sample (P) with a penetration force (F) acting on the sample (P) being specified, wherein in the region of the oscillations being produced between sample (P) and the element (106), an oscillation sensor (116) is arranged which registers the noises produced during the relative movement of the element (106) acting on the sample (P).

Abstract: The invention relates to an apparatus and a method for determining the softness of a hygienic paper or textile with at least one ply, wherein an element (106) is arranged relative to a positionally fixed sample (P), with at least one ply, of the hygienic paper or textile such that it can move and is designed such that it can be adjusted with respect to the sample (P) with a penetration force (F) acting on the sample (P) being specified, wherein in the region of the oscillations being produced between sample (P) and the element (106), an oscillation sensor (116) is arranged which registers the noises produced during the relative movement of the element (106) acting on the sample (P).

Abstract: The invention is directed to a device for measuring the streaming potential of fibers and particles in suspensions, in particular a device for determining the zeta-potential of the particles of aqueous suspensions containing fibers and particles, by measuring the streaming potential, and by subsequently computing the zeta-potential with an empirical formula. In the device of the invention, a periodic pressure curve is generated by arranging in the device for measuring the streaming potential at least two vacuum vessels, with each vessel having a different constant reduced pressure. The vacuum vessels are permanently set to a different vacuum and alternatingly connected via a valve to the measurement cell with the fiber plug. The required reduced pressure in the two vacuum vessels is maintained by using at least one small, low-capacity vacuum pump and a valve controller.