how to calculate of any storage tank level through differential pressure

[Rv11]

Dear team,
pl. help ,how to calculate of any storage tank level through differential pressure.
Because i have a liquid nitrogen storage tank their are two tapping connect with signal PG and PT first tapping is connect from TOP and second is Bottom, then PT calculate the level of tank.

 

[EmmanuelTop]

See attached material and the link: Emerson Level Guide




Dejan IVANOVIC
Process Engineer, MSChE