How do I choose de number of processors with paraFoam?
 

I have installed de Third Party software following the instructions in the OpenFOAM webpage and it compiles with the option for using several processors inactive (-mpi). I've recompiled activating the option because the graphic postprocessing goes slow and when I type

paraFoam

it seems to directly execute

mpiexec -np 64 ...

so it opens 64 subprocesses and the machine collapses.
How can I do to be able to choose the number of processors to activate?
The case was run only with 8 processors and the paraFoam script states that the maximum number is 32 so I don't really know what is the cause for the collapse of the machine.
There should be a way to pass the number of processors to the program without recompiling, shouldn't it?

If anyone can help me, I'll be gratefull.

Greetings
Enrique