The invention is a process tank containing a direct level magnetostrictive measurement system disposed directly in the tank, where the level system preferably communicates to a remote location. One embodiment of the invention embodies an internal well guide chamber, which exactly replicates the actual vessel's internal conditions (pressure and temperature), and also prevents the float from being affected by turbulence from a two phase condition, such as might occur if boiling or flashing is present inside the vessel. The process tank should have a fluid temperature different by more than 50° C. from the ambient environment, or alternatively, be a flashing tank.