Pressure Definition of Pressure Fluid pressure: Force per unit area exerted by a fluid in a solid wall. Force acts perpendicularly to the surface in contacts. Fluid is a co u d s common word for gas a d/o liquid. o od o and/or qu d Pressure is a scalar quantity. It has the units of: N/m2 or Pa (or kPa) in SI system of units psi in Imperial system of units Pressure can also be expressed in terms of height of a column of liquid List of units of pressure measurements & conversion of units Pascal s Pascal’s law Scalar quantityUnits of Pressure SM(2) Pressure Pressure measurements Absolute pressure Gauge Pressure … divided into three different categories: 1. Absolute pressure – which is defined as the absolute value o pressure (force-per-unit-area) ac g o of p essu e ( o ce pe u a ea) acting on a surface by a fluid. su ace ud Abs. pressure = pressure at a local point of the surface due to fluid – absolute zero of pressure (see page 63 of lecture notes) 2. Gauge pressure – difference between abs. pressure and atmospheric pressure – is always positive 101. 325 kPa or 14.
