The different units of pressure :
1) N/M² ( Newtons Per meter Square)
2) Pascal (Pa)
3) Bar
4) Torr
5) mm Hg (Millimeter of Mercury column)
6) mmWC (Millimeter of Water Column)
7) PSI (Pounds per Square inch)
8) Psia (Pounds Per Square inch absolute)
9) Psig (Pound Per Square inch gauge