My Go/No Go test does not change color at all until 25 seconds have past and then it instantly turns yellow. Does this mean this oil is not suitable for the BioPro 190? I have not done an actual titration as the manual recommends using the go/no go.

Hello sheepfarmer

Perhaps it means the oil is good if you react it within 25 seconds.

Not having a lot of experience with the go nogo test they provide, I will guess what your result means.

The oil you are testing is on the cusp of go/no go. After 25 seconds, enough CO2 has reacted with the catalyst that it changes and neutralizes the base to create the yellow color.

Are you shaking it?
If not, you need to shake it after you put the oil in.

If it changes to yellow after 25 seconds, then yes, that's a fail.

It means it fairly close to the upper limit, but if it goes yellow after 25 sec, yes, it's a fail.

Also, to explain how this works to the rest of the folks....

It's just a reverse titration.

Think of it like adding enough titration solution to a cup to be equivalent to 5% free fatty acid (roughly 9 mL of titration solution if using a KOH titration solution of 1 gram KOH to 1 liter of water).

The indicator in it is Phenolphthalein.
-Graydon
-Graydon