A vibrating wire viscometer for measurements at elevated pressures

A vibrating wire viscometer is described which has been used to measure the viscosity of liquid helium at varying temperatures and pressures. The viscosity is calculated from measurements of the decay time and frequency of a taut vibrating wire damped by the fluid, of the wire density and diameter, and from knowledge of the density of the fluid being measured. This viscometer is an outgrowth of one previously developed which operated only at the vapour pressure. The new device is usable at elevated pressures and requires only a small volume of fluid.