Yeah, the "it is long over 7 hours" do sounds awkward, in this way. Without punctuation marks in-between. And without brackets.
      In fact, I have seen sentences like these:
      This film is long, over 2 hours, and it took me a while to get all the way through it.   

by the end of the film, I felt as though I was a part of this family
      [O filme é longo, mais de duas horas (de duração), and levei algum tempo para entendê-lo completamente. No final, me senti comose fosse parte da família.]

It may be especially appropriate if your operation is long (over 2 hours).

I saw the film this afternoon. IT IS LONG. Over 2 hours.
++++++++++

                   the running time - as horas de funcionamento.

Para ilustrar, alguns exemplos, sobre horas de funcionamento de um humificador; por exemplo.

"1 hour of the continual operation time, 4 hours of intermittent time."
"...2 tanks for easy filling and longer run times..."
"Up to 12 hour run time per filling..."
"The humidifier has a 1.2 gallon water tank with a run time of 55 hours "
"Large tank for up to 24 hours run time per filling."

    T hus, Eddie´s right, it´s confusing.
     I think the author either meant "Misting time is long, over 7 hours." conveying "The operation time of the misting fan is 7 hours, per filling."       Or something in this way.

     PP.