What is the false statement about using nitrogen in a pre-action system?

In a pre-action fire sprinkler system, nitrogen can indeed be used effectively for several reasons. One of the primary functions of using nitrogen is to maintain a dry environment by displacing moisture that could cause corrosion in the piping and components.

The statement that nitrogen should never be used is false because nitrogen is actually beneficial; it does not support combustion and helps preserve the integrity of the system by reducing the risk of corrosion. In addition, nitrogen can completely replace air in certain situations, contributing to an inert environment that minimizes the potential for oxidizing reactions.

The other statements reflect accurate aspects of nitrogen's role in these systems: it is an inert gas and does not cause corrosion, and using nitrogen as a replacement for air is a valid practice in certain contexts within pre-action systems to enhance performance and longevity.