1 . Vo=W/(M1PoAo) —->throttling velocity unit m/s
Ao—->valve throttling area :m2
2. KE = Po*Vo*Vo/(2*M) <Kpa> M=1000 Po: kg/m3 Vo:m/s
3. KE = Pc*C/(2*M) For gas and steam ,the fluid velocity at the trim outlet may be sonic.if it is the density of the fluid at the trim outlet must be higher than the outlet desity. in order to pass the given mass flow rate.This higher density can be estimated using Equation 1. by substituting the fluid’s sonic velocity for the outlet velocity and solving for density.then this density and sonic velocity are used in equation 2 to find the kinetic energy.
Velocity criteria for liquids are much lower than forgases because liquid densities are much higher,resulting in higher energy levels.while the velocity limits are quite different,the kinetic energy limits are very close to the same.
fluid velocity requirements,base on the vapor pressure of the fluid (at design temperature) is governed by the following equation: V=SQRT(1000*(P2-Pv)/p) v:m/s P2,Pv : Kpa p : kg/m3
COEFFICIENT = 0.0509*trim throtting area(mm2)/SQRT(flow path resistance coefficient)
the outlet density can be estimate form eqution: outlet density=previous density*outlet pressure/prev pressure.