> A bit of abstract woud help, what is SUS ? what is cSt ? I understand cSt = centiStokes !
> For what purpose do you need to get cSt out of SUS ? Will it be useful for the public or simply
> an in-house utility. Sometimes we do things for personal use and suddenly
> they explode as a breakthrough in the public domain, you see my points.
Right now I'm a bit overwhelmed with the bounty of results provided. I need to spend some time looking over and understanding how the solutions provided work. Thanks to everyone for helping!
What I can do now (relatively) quickly is to fill you in on my understanding of the history of SUS/SSU and cSt.
I started looking at this when I was setting up a sheet with various methods I have found for predicting the viscosity/thickness of a blend of two different viscosity component liquids (such as motor oils).
I came across one blend formula I wanted to try that specified the viscosity in 'Saybolt Universal Seconds'.
In the 'old' days, a popular way to measure Viscosity (at least in the US petroleum industry) was with a device called a 'Saybolt Viscometer'. This contraption measured viscosity by timing how long it took for a specific amount of liquid to drain through an orifice under the influence of gravity (at specific temperatures).
The results were recorded in Saybolt Universal Seconds (sometimes also known as Saybolt Seconds Universal as well). Eventually this became defunct and was replaced with the use of the centistoke units (so you no longer had a unit based on the results from a type of device as much as a physical property).
Formulas were empirically devised in the industry to convert between cSt and SUS to allow old published works to still be used. I've only found a few of these these formulas, and some are much more accurate than others (or have differing ranges over which they are accurate).
At least, that's my understanding...
I came across what looks like the most accurate conversion formula I've seen so far. But, it's only in the form of taking the cSt value, and returning the equivalent SUS from this.
I erroneously thought that there might be an inverse form that wouldn't be much worse than the original...
In my case, I don't really need the conversion other than to convert from cSt (on input) to SUS for the blend formula, and then take the results in SUS and convert that back to cSt for the result.
So, a relatively simple SUS to cSt formula might have some interested parties, but I would have to guess that it's probably a limited group. (Perhaps of octogenarians who remember using SUS 🙂
At any rate, I plan to look over the various solutions. It'll just take me some time to look over the bounty of worksheets...
Thanks;
-Greg