ViscosityViscosityand

2-Phase Flow

Two things to remember:1. Cavitation is less damaging

when flashing exists.

2. The CV sizing process is NOT the same as for single phase fluids.

Viscous fluids cavitate very little, or not at all. For example:

How much do these

fluids cavitate?

ViscosityViscosity

Fuel oilFuel oilCrude oilCrude oil AsphaltAsphalt

Be “careful” when sizing!

This method is

DoDo NOT size for the liquid size for the liquid CCVV and the gas C and the gas CVV, and , and

in error!

simplysimply “add”“add” them together! them together!

grossly

2-Phase Flow2-Phase Flow

Air supply = 60 psiPipe size = 4” sch 40Action = Air-to-Open, Fail-Closed

Fluid = Isobutane and Methane oT1 = 100 F

P1 = 300 psiaP2 = 50 psiaFlow:

Liquid (Isobutane) = 500 gpmGas (Methane) = 50,000 SCFH

PMAX = 250 psi

2-Phase Flow Example:2-Phase Flow Example: