What is BS 4151 - Pneumatic valve positioners about?
BS 4151 is a British standard that specifies tests designed to determine the performance of pneumatic valve positioners which accept input signals of 3 lbf/in2 to 15 lbf/in2. Although some valve positioners may be tested without being fitted to a valve operator, there are some positioners that form an integral part of the operator and these cannot be separately tested.
The method of evaluation described in BS 4151, 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.
Note: Throughout BS 4151 the term “valve operator” is used; alternative and equally appropriate terms used within the industry are “valve motor” and “valve actuator”.
Who is BS 4151 - Pneumatic valve positioners for?
BS 4151 on pneumatic valve positioners is useful for:
- Valve manufacturers
- Testing centres
- Quality control personnel
- Pneumatically operated devices manufacturers
- All industrial manufacturers
- The oil and gas industry
- The power industry
Why should you use BS 4151 - Pneumatic valve positioners?
The Pneumatic Valve Positioner is a device that uses the force balancing concept to position the control valve stem in response to a pneumatic signal from a controller or manual loading station, regardless of packing box friction, actuator hysteresis, or imbalanced valve plug forces. A positioner's primary duty is to give pressurised air to the valve actuator, allowing the valve stem or shaft to correspond to the setpoint from the control system.
BS 4151 provides its users with guidelines for test methods for accuracy, performance, vibration, and endurance. Using BS 4151 guidelines helps its users with high quality, reliable and durable equipment for quality management and longer service life.
