Storage Tanks

You can Google "Nitrogen Blanket" and find a wealth of information including various layouts of a nitrogen blanket system.

One application I am familiar with is using a nitrogen blanket with Thermon which is heat trace fluid. We used a nitrogen blanket of 4PSI in the reserve/overflow tank (500 Gals.) to keep the Thermon from absorbing water and to prevent oxidation of the Thermon.

One of the functions is to exclude one of the three items at the corners of the Fire Triangle from the tank vapour space.

Another might be to exclude atmospheric moisture from a moisture-sentitive product.

Another might be to provide an inert atmosphere that will prevent biology flourishing.

It all depends upon what is in the tank, which isn't stated in the post.