Large scale industrial machinery tends to be painted in colours which are quite bright - I have seen ships' main engines coloured a pale green - this colour (the smiley) precisely:
Light blue, bright orange, red and yellow also exist.
If the installation is civilian, I'd go with one of these. If it's military, then it would be a dull grey (practically unpainted other than the base coat and any labels) or some colour similar to the landscape - not camo, as that would probably work better on a building housing the equipment.
As an example, here's a B&W main engine, with partial cut-away, in the green I mentioned.