Making a viscometer (viscosimeter) ?

[scrilla103]

Hello everybody, I am currently working on a science project and have reached the point where I need to measure viscosity of various fluids to a point of acceptable accuracy. For this I need to construct or buy a viscometer to do this. Does anybody have any suggestions on what type I should construct/buy.

Note: I do not intend to spend a lot of money on this device unless necessary. Thanks for the help.

[John Cuthber]

The simplest is to use an ordinary pipette. You time how long it takes to empty and the time depends on the viscosity.

Don't forget that viscosity is usually strongly dependent on temperature.

[Mr Skeptic]

Yup, all you have to do is have fluid of a given volume fall through a thin pipe (I think though a hole will work too but I'm not familiar with the equations). You then calibrate it with water at a given temperature, which you can look up the viscosity of. Then fill the same volume with your fluid and see how long it takes to drain.

[insane_alien]

a slightly more complicated one is to take a rod, dunk it in the fluid and see what rotational velocity you can get out of it for a given torque

[scrilla103]

Okay, I've decided to use the tube viscometer in which a liquid drains through an opening. After experimenting I am still stuck on where to plug the measurements in. I am measuring in Pascal seconds (Pascal = Newton per meter squared; Newton = Kilogram meter per second squared), thus {Kilogram}{Meter/Second^2}/{Meter^2}. I used a simple bottle and cut off the bottom for relative testing to see if I was on the right track; apparently I am not. I used .5 Kg and multiplied by the force of Gravity (9.80m/s^2); then I divided by the area of the opening of the bottle (diameter-.015 Meters^2 X Pi = .000707...); the relative time was between .5 and 2 seconds. In the end the final measurement is no where near the value I acquired online (.001003 Pa S) My assignment of values to the unit were as such: Kg-Mass of liquid; (m)/(s^2)- gravity; m^2- area of opening where liquid drains; s-time in seconds for drain. Any ideas?

[John Cuthber]

It's not what I'd call trivial.

http://en.wikipedia.org/wiki/Hagen%E2%80%93Poiseuille_equation