BS 4151:1967

Co-operating organizations
Foreword
Method of evaluation
1 Scope
2 Terminology
3 General testing procedure
4 Static behaviour
5 Dynamic behaviour
6 Air flow
7 Other considerations
Figures
1 Dead zone, relationship of stem position to input
   signal
2 Relationship between amplitude and frequency
3 Flow characteristic of a valve positioner at an
   output of 9 lbf/in2

Specifies tests to determine performance of pneumatic valve positioners with 3 to 15 lbf/in² (gauge) input signal. Method of evaluation specifies use of a valve operator of a spring-opposed or double-acting diaphragm or piston type in order to allow a ready comparison to be made between different types of positioner.

This standard specifies tests designed to determine the performance of pneumatic valve positioners which accept input signals of 3 lbf/in² to 15 lbf/in².

NOTE Throughout this British Standard the term “valve operator?? is used; alternative and equally appropriate terms used within industry are “valve motor?? and “valve actuator??.

Although some valve positioners may be tested without being fitted to a valve operator, there are some positioners which form an integral part of the operator and these cannot be separately tested. The method of evaluation described in this standard therefore specifies the use of a valve operator in all cases since this allows a ready comparison to be made between different types.

The operator may be a spring-opposed or double-acting diaphragm or piston.