DP used for liquid valve sizing

[HANYWEPCO]

When we make sizing for liquid flow in a control valve , we first check DP allowable and compare it by our maximum DP , if our maximum DP is greater than allowable DP ,we use DP allowable for sizing,Why?

 

[MFJewell]

Allowable is the most you want it to be. Maximum is the most it could actually be based on certain system conditions.

 

[gerhardl]

I dont know why, and to what rule.

Any system, all factors considered, must be constructed to be safe. All actual operational conditions must be taken in to consideration when dimensioning and selecting a system solution.