When printing from Acrobat gray color prints with purple tint.

I would also check your print driver to see if it has a button to check off that says keep black as black. We had a similar issue with our blacks where printing out with a red tone. We run our files through a workflow and in that workflow we set up que that dump into hot folder that then printout our files. What we found is that our que had a option to keep blacks black that needed to be checked off. When this wasn't checked the printer interpreted the black differently adding all four colours to it. Maybe that is what is happening with you. I'm not sure of your environment but if your working from a workflow then maybe check to see if there is an option of keeping blacks as black.

hope this helps

When grey comes in some strange colours my most obvious guess would be, that there are RGB grey colours that are incorrectly separated to CMYK grey, which is simply a shade of K as Dov Isaacs​ assumes.

I sometimes voluntarily mix some Cyan to my grey to give it a bluish appearance.

The question is exactly what is the color that you consider to be gray based on visual appearance on the screen?

If you are using Acrobat Pro DC, you can use the Output Preview tool's Preview Object Inspector to ascertain the actual colors and color spaces of the object under the cursor on the document's page. For example, unless you have CMYK= 0,0,0,0 or DeviceGray (any value), you will likely get printing with a mixture of colors instead of just black.

There is an option in the Print Dialog's Advanced dialog's Color Management tab for Treat grays as K-only grays. If this option is not enabled, please enable it and see if that resolves your problem. That option forces ICC color managed gray and any RGB for which R=G=B (RGB “gray”) to print only with the black toner or ink. If this is not a PostScript printer you are printing to, you might check your print driver's options to see if they have a similar option that will resolve this problem.

          - Dov