The addition of a diluent enables the diluted fluid (dilbit in the case of bitumen) to meet pipeline specifications in order for it to be efficiently transported.
In other cases such as PUREX nuclear reprocessing the diluent (kerosene) is used to reduce the maximum metal loading which the organic layer can reach.
This is the weight of the active acetaminophen, while the tablet weighs more due to other additives known as diluents.
These additives may be used as binders, disintegrants (help the tablet break apart in the digestive system), or flavor enhancers.
Some very common diluents in tablets include starch, cellulose derivatives, and magnesium stearate (a lubricant).
Diluent gases for this use are metabolically inert and non-toxic, but may have some level of narcotic effect at high partial pressure.