Page 17 - Valve Selection Handbook

4 Valve Selection Handbook

turers. Equations presented in coherent units are valid for solving in
either SI or imperial units.

Identification of Valve Size and Pressure Class

The identification of valve sizes and pressure classes in this book fol-
lows the recommendations contained in MSS Standard Practice SP-86.
Nominal valve sizes and pressure classes are expressed without the addi-
tion of units of measure; e.g., NFS 2, DN 50 and Class I 50, PN 20. NPS
2 stands for nominal pipe size 2 in. and DN 50 for diameter nominal 50
mm. Class 150 stands for class 150 Ib. and PN 20 for pressure nominal
20 bar.

Standards

Appendix C contains the more important U.S., British, and ISO stan-
dards pertaining to valves. The standards are grouped according to valve
type or group.

This book does not deal with control valves. Readers interested in this field should con-
sult the following publications of the ISA:

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1. Control Valve Primer, A User's Guide (3 edition, 1998), by H. D. Baumann. This book
contains new material on valve sizing, smart (digital) valve positioners, field-based
architecture, network system technology, and control loop performance evaluation.
st
2. Control Valves, Practical Guides for Measuring and Control (1 edition, 1998), edited
by Guy Borden. This volume is part of the Practical Guide Series, which has been devel-
oped by the ISA. The last chapter of the book deals also with regulators and compares
their performance against control valves. Within the Practical Guide Series, separate
volumes address each of the important topics and give them comprehensive treatment.
Address: ISA, 67 Alexander Drive, Research Triangle Park, NC 27709, USA. Email
http://www.isa.org