DERELIKT Hazmat Suit Route in Central Security

Quick answer

In Central Security, take the stairs to the landing marked 2 and turn left at the HAZMAT STORAGE sign.

Steam Demo

Reach the landing marked 2

After speaking with Louis Hartman, use the exit labeled TO CENTRAL SECURITY.
Once inside Central Security, climb the stairs to the landing marked 2.
Follow the HAZMAT STORAGE arrow to the left. The mesh-lined corridor is the other branch.