scope:

This standard is intended to permit a variety of positioning devices which respond to a linear motion to be mounted on the actuator of a control valve, either directly or by employing an intermediate mounting bracket. There is a large variety of types, sizes and designs of actuators. The following parameters define the intended applicability of this standard for the guidance of manufacturers and users. 1. The standardized mounting applies only to positioners which are mounted on the side of the actuator. 2. The standardized mounting applies in general only to those actuators which have a travel of 100 mm or less. 3. The standardized mounting is designed to cover three basic types of actuator design: a. those with some form of cast or fabricated yoke to connect the actuator power unit to the valve; b. those which use some form of central tube yoke to connect the actuator power unit to the valve; c. those in which the yoke incorporates two or more columns or pillars to connect the actuator power unit to the valve.