SI Units

Units for pressure

SI unit for pressure:

• Pascal (Pa)
  * Pressure = Force / Area
  * 1 Pa = 1 Newton acting over 1 square metre
  * 1 Pa = 1 Nm^-2.

Conversions

• 1 kPa
  = 7.5mmHg
  = 10.2 cmH2O
  = 0.00987 ATA
  =0.146 psi
• 1 mmHg
  = 1.36 cmH2O
  = 0.019 psi
  = 0.133 kPa
• 1 cmH2O
  = 0.735mmHg
• One atmosphere absolute
  = 1 ATA
  = 760mmHg
  = 101.3 kPa
  = 14.7 psi
  = 1.013 Bar
  = 1033 cmH2O

NB

• psi = pound per square inch
• 1cm of H2O = 0.735mmHg (see above)
• 1cm of blood = 0.77mmHg
• 1J = 1 L.kPa = 1 Nm
• 1 N = 100000dyne = 1 kg.m.s-2
• 1 Pa = 1 Nm-2 = 10 dyne.cm-2

 

Units for resistance

• 1 kPa.L-1.s
  = 10.2cmH2O.L-1.s
  = 10 dyne.cm-5.s
  = 7.5 mmHg.L-1.s
  = 0.125 mmHg.L-1.min