ISA RP75.21 PDF

The document describes a technique for the communication of process data and other special requirements among the parties involved to facilitate the selection of control valves, their actuators, and accessories. The technique includes, but is not limited to, such features as a process data envelope, a process schematic, a process piping configuration, and a process data worksheet, which may be used in combination or in part as appropriate to the specific application. Development and verification of design and actual process conditions at the final control element are more easily and thoroughly accomplished using a "standard format."

Purpose

The purpose of this document is to assure an adequate exchange of process conditions and other pertinent information between the process system designer or the person who specifies the control valve, and the control valve supplier. The technique is not intended for use on all normal applications, but it may be a useful tool for obtaining the process data needed. Several suggested extraordinary applications where very complete data is required are listed in Section 9.