Different cups have different shapes and hole sizes and because times too short or too long are unsuitable, for any given viscosity there is an optimum cup with times in the 15-60s range. The size of the hole is in mm and a Zahn #4 means a Zahn cup with a 4mm hole.
How do you convert viscosity units?
Common Dynamic or Absolute Viscosity Units
- 1 Pascal second (Poiseuille) = 1000 Centipoise.
- 1 Pascal second (Poiseuille) = 10 Dyne second / centimetre2
- 1 Pascal second (Poiseuille) = 0.0102 Gram force seconds / centimetre2
- 1 Pascal second (Poiseuille) = 10 Gram / centimetre second.
What is the best way to measure viscosity?
Ways to Measure Viscosity
- Capillary Viscometer. The earliest methods for measuring viscosity were based on using capillary tubes and measuring the time it took for a volume of liquid to pass through the length of the tube.
- Zahn Cup.
- Falling Sphere Viscometer.
- Vibrational Viscometer.
- Rotational Viscometer.
What is the units of viscosity?
The unit of viscosity is newton-second per square metre, which is usually expressed as pascal-second in SI units.
How do you measure viscosity without a viscometer?
Alternative viscometers only allow for single point measurement and provide only shear viscosity measures. Viscosity can also be measured by applying oscillating vibrations to the sample and monitoring the damping effects of the fluid.
What is viscosity cup?
A viscosity cup is an instrument used to determine a fluid’s thickness and flow resistance. This is done by introducing a sample of the fluid into a container with a hole in its bottom and recording the time it takes for the container to empty when draining the fluid through the opening.
How do you calculate the viscosity of a cup of liquid?
Because these cups actually measure the kinematic viscosity in cSt (a denser liquid flows out faster), enter your estimated density to allow the conversion (cP=cSt*ρ). If you have ever measured a real viscosity and compared it to a value from one of the “standard conversion tables” you will probably be surprised at the difference.
What is the viscosity of a 20S Zahn 2 Cup?
If you have ever measured a real viscosity and compared it to a value from one of the “standard conversion tables” you will probably be surprised at the difference. In preparing this app I looked at many such tables and a 20s Zahn #2 cup viscosity varies from ~20-45cP depending on the table.
How accurate are shear thinning Cups?
First they are not accurate even when done properly (see below) and even less when they aren’t cleaned properly between use, etc. Second, they assume Newtonian viscosity, so they tell you nothing about shear thinning. An expert in the field has warned me that this app might add legitimacy to the use of these cups.
