What the 321 Dip Viscosity Cup does – Sinotime
Purpose and application
Quick viscosity measurement of any fluid, such as paints, varnishes, wet enamels, gravure printing inks, dyes and leather finishes, oils, greases and foodstuffs.
Measuring principle
The viscosity of a substance is expressed as the time a set volume of liquid (usually 100 ml) takes to run completely out of a cup with an orifice of specified diameter. The efflux time is measured with a stopwatch.
Test procedure
Dip the cup fully into the substance so that it fills completely. Then lift the cup out quickly and start the stopwatch at the same moment. Stop the stopwatch, in seconds, as soon as the orifice can be seen from above through the cup, i.e. when the substance has run out. Take care to keep the cup vertical throughout the test.
What is a viscosity cup?
A viscosity cup is a simple gravity device that times how long a known volume of fluid takes to flow through the orifice of a cup, which can come in various shapes. Under ideal conditions, the efflux time can be converted to kinematic viscosity (stokes or centistokes), depending on the fluid's specific gravity. In many applications the absolute viscosity is not needed, and the efflux time in seconds is enough to rank fluids relative to each other.
Using viscosity cups
Over the years, at least 50 different types of viscosity cup have been invented and used, mainly for production control and on-site testing. Most simple cups fall into two groups: those filled and drained on a fixed stand, and those dipped straight into the fluid's container and drained back into it. Whichever method you use, follow these rules:
1. Take care when measuring thixotropic or other non-Newtonian fluids, because a defined shear rate cannot be produced in a viscosity cup.
2. Choose a suitable orifice diameter, and keep using it, so that efflux times fall accurately within the specified minimum and maximum.
3. Control the temperature during efflux, and only measure with an undamaged orifice.
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