Putkiviskometria

Putkiviskometria, also known as pipe viscometry, is a method for determining the viscosity of fluids. It relies on measuring the time it takes for a known volume of fluid to flow through a tube of specific dimensions under a controlled pressure or gravitational force. The fundamental principle is based on Poiseuille's Law, which describes the laminar flow of an incompressible fluid through a cylindrical pipe. This law relates the flow rate to the pressure drop, the viscosity of the fluid, and the dimensions of the tube.

In practice, a putkiviskometri apparatus typically consists of a reservoir to hold the fluid, a capillary tube of a defined length and diameter, and a mechanism to apply a consistent pressure difference across the tube. This pressure can be generated by a pump or by the hydrostatic head of the fluid itself. The time taken for a specific volume of fluid to pass through the capillary is measured. By knowing the volume of fluid, the dimensions of the capillary tube, and the applied pressure, the viscosity of the fluid can be calculated using variations of Poiseuille's Law.

This technique is particularly useful for measuring the viscosity of Newtonian fluids, where viscosity is independent of shear rate. Variations of the method exist, employing different methods for applying pressure and measuring flow rate. Putkiviskometria finds applications in various industries, including chemical processing, food production, and pharmaceuticals, for quality control and process monitoring. It offers a relatively simple and cost-effective way to characterize fluid behavior.