ISA 75.25.01

Scope and limitations

This standard defines the testing and reporting of step responseof control valves that are used in throttling closed loop controlapplications. A control valve consists of the complete,ready-to-use assembly of the control valve body, actuator, and anyrequired accessories. The most probable accessory is a valvepositioner. For background, refer to technical reportISA-TR75.25.02-2000 (R2010), Control Valve Response Measurementfrom Step Inputs.

If this standard is used for evaluation or acceptance testing,the parties may agree to documented variations from theserequirements.

This standard does not define the acceptable control valveperformance for process control nor does it restrict the selectionof control valves for any application.

This standard defines methods and criteria for performingresponse tests and evaluating test results for three alternativeenvironments – “bench testing”, “laboratory testing”, and”in-process testing”. “Bench testing” is testing without flow suchas in a plant instrument shop, laboratory, or control valvemanufacturing site. “Laboratory testing” is testing with flow in alaboratory. “In-process” testing is performed in a plant duringnormal plant operation with process flow.

Purpose and limitations

The purpose of this standard is to define how to test, measure,and report control valve response characteristics. This informationcan be used for process control applications to determine how welland how fast the control valve responds to the control valve inputsignal. It does not define acceptable process control, or restrictthe selection of control valves to any application, since processrequirements and user objectives vary widely.

The information is specifically applicable to closed loopfeedback control but may have some application to open loop controlapplications. It does not address valves used in on-off controlservice.

Tests specified in this standard may not be sufficient tomeasure the performance required for all applications. Not allcontrol valve applications will require this testing.

Edition:

00

Published:

01/01/2000

ANSI:

ANSI Approved

Number of Pages:

34

File Size:

1 file , 240 KB