How to choose controlling valve
1. Parameter
Kind of fluid which is to be controlled
Fluid temperature
Fluid viscosity
Fluid specific weight
Required negotiability(max flux, normal flux, min flux)
Inlet pressure(max, normal, min)
Outlet pressure(max, normal, min)
Pressure difference in normal flowage
Max permitted level of noise
Whether superheat and flash vaporization exists
Diameter of inlet and outlet, wall thickness
Required special item information
Material of valve body
Way of connection and pressure level of valve
Required action when the gas is leaking
Instrument air which can be supplied
Instrument signal
Manner of drive
2 the process of choosing type of valves
Confirming the Operating condition
(P1,△P, Q, T, discharge characteristic, permitted noise, etc)
Choose the pressure level adopt to the valve body and valve trim
Initial value of Cv required by computing
Check the noise level and cavitation number
Choose the type of valve trim
If there is no prompting about noise and cavitation, choose the standard valve trim
If the noise of the gas phase is big, choose the valve trim which can reduce the noise
If the noise of the gas phase is big or there’re cavitation, choose the the valve trim which can reduce the noise and resist the cavitation
Choose the dimension of valve body and valve trim
Choose the dimension of valve body and valve trim according to required value of Cv
Choose the material of valve trim
According to the application situation, choose the material of valve trim, so as to meet the requirements
Option
Accessory, bonnet, filler