ISA 51.1

This Process Instrumentation Terminology Standard is intended to include many specialized terms used in the industrial process industries, to describe the use, performance, operating influences, hardware, and product qualification of the instrumentation and instrument systems used for measurement, control, or both. There are many terms and definitions relating to performance tests and environmental influences (operating conditions) as further explained in the Introductory Notes (Paragraph 3.2). Basically, this document is a guideline for vendor/user understanding when referring to product specifications, performance, and operating conditions. Process industries include chemical, petroleum, power generation, air conditioning, metallurgical, food, textile, paper, and numerous other industries.

The terms of this Standard are suitable for use by people involved in all activities related to process instrumentation; including research, design, manufacture, sales, installation, test, use and maintenance.

The Standard consists of terms selected primarily from Scientific Apparatus Makers Association (SAMA) Standard PMC20.1 and American National Standards Institute (ANSI) Standard C85.1. Additional terms have been selected from other recognized standards. Selected terms and definitions have not been modified unless there was a sufficiently valid reason for doing so. New terms have been added and defined where necessary.

This Standard is primarily intended to cover the field of analog measurement and control concepts, and makes no effort to develop terminology in the field of digital measurement and control.

Purpose

The purpose of this Standard is to establish uniform terminology in the field of process instrumentation. The generalized test procedures described in Section 5 are intended only to illustrate and clarify accuracy-related terms. It is not intended that they describe specific and detailed test procedures.