Chapter 2 Fundamental Hydraulic Fluid Mechanics 2.The definition of pressure (1)Absolute pressure (2)Relative gauge pressure:The pressures measured by a pressure gauge are all relative pressure (3)Vacuum (negative pressure) The units of pressure and relations between different pressures 1Pa=1N/m2;1bar=1×105Pa=1×10sN/m2; 1at=1kgf/cm2=9.8×104N/m2;1mH20=9.8×103N/m2; 1mmHg=1.33×102N/m2. The relationship of three pressures is shown in Fig.2-5. 15 Homepage List Upwards Downwards Return ExitChapter 2 Fundamental Hydraulic Fluid Mechanics 15 2. The definition of pressure (1) Absolute pressure (2) Relative gauge pressure ：The pressures measured by a pressure gauge are all relative pressure (3) Vacuum (negative pressure) 1Pa＝1 N/m2；1bar＝1×105 Pa＝1×105 N/m2 ; 1at＝1kgf/cm2=9.8×104 N/m2 ; 1mH2O＝9.8×103 N/m2 ; 1mmHg ＝1.33×102 N/m2 . The relationship of three pressures is shown in Fig. 2-5. The units of pressure and relations between different pressures ：