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# Calculations related to Flow and Pressure

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## Pressure-Flow Calculations

1. Theoretical changes in pressure after changing particle size
2. Ergun Modification of the Blake-Kozeny Equation for Pressure-Flow
3. Pressure conversions starting with psi
4. Pressure conversions starting with bar
5. Pressure conversions starting with kg/cm2
6. Pressure conversions starting with kPa
7. Pressure conversions starting with MPa

1. Theoretical changes in pressure after changing particle size: Where:  ΔP1 = Initial pressure (any pressure units)
ΔP2 = Calculated pressure (same pressure units as P1)
dp1  = Initial mean particle size (any units but typically µm)
dp2  = Mean particle size of new resin (same units at dp1)

2. Ergun Modification of the Blake-Kozeny Equation for Pressure-Flow: Where:
ΔP = Change in pressure
L = Column Length
η = Mobile phase viscosity
u = Empty column linear velocity (cm/hr)
dp2 = Mean particle size
ε = Interstitial void volume intrinsic to each resin

3. Pressure conversions starting with psi:

To convert to kg/cm2 from psi multiply by 0.0703
To convert to bar from psi multiply by 0.0690
To convert to kPa from psi multiply by 6.895
To convert to MPa from psi multiply by 0.00690

4. Pressure conversions starting with bar:

To convert to kg/cm2 from bar multiply by 1.0197
To convert to psi from bar multiply by 14.504
To convert to kPa from bar multiply by 100
To convert to MPa from bar multiply by 0.100

5. Pressure conversions starting with kg/cm2: To convert to psi from kg/cm2 multiply by 14.223
To convert to bar from kg/cm2 multiply by 0.981
To convert to kPa from kg/cm2 multiply by 98.067
To convert to MPa from kg/cm2 multiply by 0.0981

6. Pressure conversions starting with kPa: To convert to kg/cm2 from kPa multiply by 0.0102
To convert to bar from kPa multiply by 0.01
To convert to psi from kPa multiply by 0.1450
To convert to MPa from kPa multiply by 0.001

7. Pressure conversions starting with MPa:

To convert to kg/cm2 from MPa multiply by 10.197
To convert to bar from MPa multiply by 10
To convert to kPa from MPa multiply by 1000
To convert to psi from MPa multiply by 145.04