Have you considered a listbox?

It could display the list of your values, ie Circulating Rates, Injection Rates, Acid etc.

The listbox could be set up to allow the user to make multiple selections.

Then rather then looping through controls on a userform you could loop through the list in the listbox.

Oops, just realised I might be sounding as though I'm trying you sell you a listbox.

Sorry about that, why not just have a think about it?