View Full Version : DIY viscosity cup

13th February 2012, 02:06 PM
Here's my newest viscocity comparator and the cheapest as well!
It has a 3mm hole in the screw-on-cap and a handy flip valve in the cap.
I cut the bottom out of the plastic bottle.
I fill the bottle while "inverted".... get the stopwatch ready... then open the cap and time it till the flow first quits.
I can compare viscocity of 1 batch to another, or to that of diesel.
The next step is to log readings and compensate for temperature.
I hope you like it and it helps save you a dollar...

Tony From West Oz
13th February 2012, 10:10 PM
Any container where you can compare the flow of the liquids of interest should work fine. Having a suitable container is a good start. Taking multiple readings of each liquid is good to average any human error in the operation of the stopwatch. Hopefully the averages for all operations of the stopwatch should be similar.
Having an accurate means of measuring the flow is the next part. Most phones have a stopwatch function.
Recording the flow times and temperatures of the liquids would best be done in a spreadsheet. You can then graph the relative flow times for the liquids tested, and the temperature they were tested at.

Keep up the good work.

14th February 2012, 08:04 AM
Not only will it measure viscosity but will also clean any road grime or bugs from inside your engine! Laurie

14th February 2012, 09:00 AM
A suitable container is best to have a taper leading toward the outlet.
I had a tin once that was too flat bottomed, so the pressure of the oil exiting slowed down as the level dropped,
making readings more eratic.
I use my phone stopwatch function. As the flip top is better as a 2 handed operation, I start the stopwatch and release the oil when
watch reads a nominal figure.
Can you beat this for "cost effectiveness"? This bottle was destined for the trash... err I mean plastic recycling.

As a matter of interest, diesel measures 30 seconds a couple of weeks ago when I happened to have some here.
Yesterday the oil I put in my tank registered 37 seconds. (No adjustment for temps were performed).

Am working on my next gadget to be posted on this blending forum shortly

14th February 2012, 03:28 PM
Hi Tbird650

Back in the "Dark ages" I did a lot of viscosity testing using. The World Famous Dr Pepper Viscosometer (Pat Pend) (http://biodiesel.infopop.cc/eve/forums/a/tpc/f/419605551/m/590108381/p/1)
It was one of the few meaningful backyard tests available.
If I am not mistaken, the total cost was around 20 cents. Of course back then 20 cents was a lot of money

14th February 2012, 04:57 PM

Very cool. I like the tutorial.
The write up claimed it was "something under a dollar" to construct. Perhaps that was including buying the drink!

I recall comparing engine oils quite some years ago. I used drinking straws and counted the time they took to drain out.
Simple but useful. I was comparing 20/50 and straight 50 weight oils.
Of the 2, the 50 was heaviest at room temp. Apply heat and it got to a point where I couldn't tell the viscosity apart.
For further comparison, at the same heat, a 30/40 I tested resembled kerosene.

14th February 2012, 05:46 PM
Hi tbird650
Yes, the "something under a dollar" was because I could only buy a foot of copper tubing. I only used about 1 inch of the tube.. After paying a dollar for so much excess copper tube, we all had to eat sausages for a week.

With viscosity testing using a viscosimeter temperature is everything.
If the temperatures are not exact you might as well just have a beer and watch TV.