Oil Field unit for Pressure: 1 psi = 6894.76 Pa = 6.89476 kPa
In engineering practise when Pressure value is referenced in absolute terms, including the standard atmospheric pressure, the psi unit is then referred explicitly as psia: P [psia] = P [psi].
This meant to avoid confusion when the Pressure value is referenced in relative terms as a surplus to the standard atmospheric pressure, and in this case the psi unit is referred as psig: P [psig] = P[psi] - 14.6959
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Natural Science / Engineering / Measurement / Unit