Also, I was wondering about ways to measure viscosity of filtered WVO at various temps, using various additives. Anyone know the viscosity of water at various temps? I'm wondering if I can measure the time it takes for a given volume of water to drain through a fixed size aperature...then figure the viscosity of my oil mixes by measuring the time it takes the same volume of oil to drain from the same container. Anybody out there know if I can accurately extrapolate oil viscosity ratings this way? Thanks in advance. --Chris

Chris, some difficulty exists with equipment. Viscosity can be measured by many methods, flow through orifice, ball dropping through liquid, rotating disk in stationary liquid (Brookfield Viscometer). Some measure by laminar flow some by continous flow principles, which best relates to our situation I am not sure.
Lacking any sophisticated instrument for viscosity measurement I use a 100 ml pipette and stopwatch. BD is sucked in to well above the graduated mark and timing commences when the meniscus passes the graduation. Timing is stopped when the stream of BD stops and the first drop is formed.
Some results.
Water Waste Cotten Seed oil 147.3 sec
Waste blended vegetable oil 149.3 sec
20 grade auto trans fluid 130 sec
Distilate (petroleum diesel) 30.3 sec
Various batches of BD from 34 to 37 sec

Tilly has developed a DR. Peppers viscometer and elsewhere there was talk of a bottle of shampoo which demonstrated viscosity with a pearl. A search of the site using viscosity should bring up both of these and more.
An excellent, if somewhat technical, site on test ing vegetable oils and BD is
http://koal.cop.fi/leonardo/leonardo.htm

Regards Squarepeg

Chris, go to the General Biodiesel Forum page 3 and look at the topic "Dr Pepper Viscosometer (Pat Pend)." The Viscosometer is described in detail and is great for caomparing relative viscosoties of different or similar liquids.
The repeatibility and accuracy is phenominal (I think) and it cost me less than 10cents Aus(although I did have to buy 85 cents worth of copper tubing) and took about an hour to make.


Tilly SBC/IBA Viscosity div. .

It seems a lot of members here really have their **** together. Very cool Tilly. Thanks for the info. Once an instrument is constructed, Im hoping one can calibrate it with known viscosities in centistrokes. I plan to build a TillyDrPepperViscometer and see if seconds draining is directly proportional to the liquid's viscosity. Rate of flow through a hole depends on a lot of things (temp, pressure grade (varying with height of column of test liquid), hole diameter and who knows what else), so I wonder if there are too many variables in the mix to extrapolate accurate values in centistrokes.

Every method I can think of seems to have the same confounding mix of variables except for that spinning disc method PaulG was talking about.

I think I'm a geek. Thanks guys.

Tilly SBC/IBA Viscosity Div Dr Pepper group

.....or all you ever needed to know about viscosity.

The SI unit of kinematic viscosity is the square meter per second [m2/s], which has no special name. This unit is so large that it is rarely used. A more common unit of kinematic viscosity is the square centimeter per second [cm2/s], which is given the name stoke [St] after the English scientist George Stoke. This unit is also a bit too large and so the most common unit is probably the square millimeter per second [mm2/s] or centistoke [cSt].

1 m2/s = 10,000 cm2/s [stoke] = 1,000,000 mm2/s [centistoke]
1 cm2/s = 1 stoke
1 mm2/s = 1 centistoke

Kinematic viscosity should not be confused with dynamic viscosity, absolute viscosity or simple viscosity (all the same thing) which is a measure of the ratio of the shearing stress to the velocity gradient in a fluid. Its unit of measurement is the Pascal second, or, more commonly, the dyne second per square centimeter.

H Beating one's drum Div

Let's not forget that we are more interested in the viscosity of our chosen fuel relative to the petro diesel that our pumps and injectors were designed for. Therefore, all we really need is a repeatable test. PaulG's method is therefore perfectly valid. Don't be too concerned with an absolute value in centistokes; the comparison is the important point.

If you are making biodiesel or running on SVO and want to sell the stuff (or even just keep your warranty valid) you will need to comply with the above in Europe and equivalents elsewhere in the world.

The section that deals with vicsosity specifies a measurement (in centistokes) of between 2 and 4.5 at 40 degrees C.

H