To quickly summarize, for kicks and giggles ( I have the "Nope!" option on ) I clicked on the delete fluids button and noticed that the tanks technically separated by a pump have their contents deleted.
Basically: Tank A has its contents pumped into Tank B. When I open Tank A and try to delete the fluids, (In this example specifically, chlorine gas) I get the advertised denial, but Tank B does still have it's contents voided.
I don't have the necessary restraint to stop myself from clicking the delete fluid options without thinking. That's why I downloaded this mod in the first place. I'm not positive if that's a problem with the mod or the base game, but it goes against what this mod is about and I needed to tell someone.
EDIT: I've done a little testing and I've discovered some weird things. As it turns out, the gasses are NOT deleted, what they are doing is teleporting to be equally distributed amongst all the connected tanks and pipes. In other words, weird, but not a problem.