Process Medium: Such as Hydrogen，acid water，Boiler main feed water
Design Temper/ Operating Temper ；Design Press./Inlet Press./Outlet Press./Shut-off Press.
Flow Max,Normal,Min:   
Gas: Nm3/h Steam:kg/h Liquid:m3/h or kg/h
Density/specific Gravity/molecular weight
Dynamic viscosity:   mPa.s（For Viscous liquid）
Compressibility/Critical press. Pc: For gas；  Vapor press. Pv:  For Liquid 
Is the medium special：Two phase flow or not，Whether there are suspended particles, etc

Valve Service:  such as vent valve，Syngas control valve
Pipe size/material/Press.Class
Flow Characteristic： Equal percentage/linear/quick open/on-off
Body material/Trim material
Packing and Style of bonnet
Leakage class/Flow open/close
TYPE: control valve（sliding valve，rotatry valve）Shut-off valve（ball，butterfly，gate.etc）
Connection type:flange/thread/welding

Actuator Type: Pneumatic,Electric, Hydraulic
Handwheel：top/side mount，worm gear drive?
Air/Power fail： open/close/lock
Travel time/Air press.
Positioner： smart/mechanical，feedback?，HART?FM/explosion-proof，single/double action。
Limit switch：contact type/inductive
Solenoid： 24V/220VAC，Body material：Cast aluminum or copper or stainless steel，Ex or not，low power or not?
Filter regulator： stainless or aluminum plastic?

Valve environmental requirements: no oil degreasing, no copper, fire, anti-static
Is there any brand requirement for valve accessories?
Valve overall certification and standard requirements，Sil，API6D etc.
Other requirements.