Showing posts with label electric actuator. Show all posts
Showing posts with label electric actuator. Show all posts

Wednesday, June 13, 2018

Electric Valve Actuation

Limitorque Electric Valve Actuator
Limitorque Electric Valve Actuator
Electric actuators use electrical power to actuate a valve. While most of the basic technology used in electric actuators has been around since the 1930s, decades of incremental improvement have significantly increased their functionality while dramatically reducing their cost. In recent years, these advances have reached a tipping point that makes electric actuators the first choice for a wide variety of applications.

Pros
  • Electric power is relatively inexpensive, easy to manage, and normally available to most industrial sites. The capital cost of electric actuators is typically cheaper per equivalent unit of torque/thrust output. They’re also cleaner and safer to operate. 
  • Electric actuators can provide superior positioning accuracy for control or modulating valve functions, which can include provisions for a high degree of process monitoring, data logging and information feedback. 
  • All necessary control functions are integral to electric actuators, reducing capital costs. 
  • Electric actuators significantly reduce control wiring costs by enabling distributed control. They simplify control logic by integrating control commands and feedback into customer SCADA or DCS systems. (Traditional electromechanical control systems require a dedicated wire for each command and feedback signal, leading to cable bundles with seven or more cores as minimum for each actuator. By contrast, a typical bus system can use one twisted pair wire in a daisy chain configuration to carry all required input and output signals.) 
  • As torque and thrust requirements increase, electric actuators weigh less and have smaller footprints compared to pneumatic actuators. 
  • Electric actuators may be combined with external gearboxes to produce extremely high output thrust and torque values.
Cons
  • With the exception of a few specific configurations, electric actuators can’t guarantee a fail-safe stroke but will “fail in the last position.” (Fail-safe stroke refers to an actuator’s ability to move a valve to a predefined safe position when power fails).
  • Electric actuators have more complex and sensitive components than the mechanical parts used in other types of actuators. Electronic technology also requires periodic refreshing to keep pace with component changes and improvements.
  • Beyond a certain size/torque range, electric actuators are less cost-effective and generally have limitations in operating speed when compared to pneumatic and hydraulic actuators.
  • In hazardous areas with potential exposure to explosive process media, electric actuators require more specific certifications and construction features to be considered safe for use.
Recommended applications

Electric actuation is the first choice for most oil and gas applications. They’re ideal for general process valve automation, non-critical applications, and light-duty modulating applications (generally up to 1200 starts per hour), although some can modulate continuously up to 3600 starts per hour.

Thursday, April 13, 2017

Understanding Industrial Valve Actuators

Automated Pneumatic Ball Valve
Automated Pneumatic
Ball Valve (Jamesbury)
Valves are essential to industries which constitute the backbone of the modern world. The prevalence of valves in engineering, mechanics, and science demands that each individual valve performs to a certain standard. Just as the valve itself is a key component of a larger system, the valve actuator is as important to the valve as the valve is to the industry in which it functions. Actuators are powered mechanisms that position valves between open and closed states; the actuators are controllable either by manual control or as part of an automated control loop, where the actuator responds to a remote control signal. Depending on the valve and actuator combination, valves of different types can be closed, fully open, or somewhere in-between. Current actuation technology allows for remote indication of valve position, as well as other diagnostic and operational information. Regardless of its source of power, be it electric, hydraulic, pneumatic, or another, all actuators produce either linear or rotary motion under the command of a control source.

Thanks to actuators, multiple valves can be controlled in a process system in a coordinated fashion; imagine if, in a large industrial environment, engineers had to physically adjust every valve via a hand wheel or lever! While that manual arrangement may create jobs, it is, unfortunately, completely impractical from a logistical and economic perspective. Actuators enable automation to be applied to valve operation.
Pneumatic actuator
Pneumatic actuator
(Jamesbury Quadra-Powr

Pneumatic actuators utilize air pressure as the motive force which changes the position of a valve. Pressurized-liquid reliant devices are known as hydraulic actuators. Electric actuators, either motor driven or solenoid operated, rely on electric power to drive the valve trim into position. With controllers constantly monitoring a process, evaluating inputs, changes in valve position can be remotely controlled to provide the needed response to maintain the desired process condition.

Manual operation and regulation of valves is becoming less prevalent as automation continues to gain traction throughout every industry. Valve actuators serve as the interface between the control intelligence and the physical movement of the valve. The timeliness and automation advantages of the valve actuators also serve as an immense help in risk mitigation, where, as long as the system is functioning correctly, critical calamities in either environmental conditions or to a facility can be pre-empted and quickly prevented. Generally speaking, manual actuators rely on hand operation of levers, gears, or wheels, but valves which are frequently changed (or which exist in remote areas) benefit from an automatic actuator with an external power source for a myriad of practical reasons, most pressingly being located in an area mostly impractical for manual operation or complicated by hazardous conditions.
Electric Actuator
Electric Actuator
(Limitorque)

Thanks to their versatility and stratified uses, actuators serve as industrial keystones to, arguably, one of the most important control elements of industries around the world. Just as industries are the backbones of societies, valves are key building blocks to industrial processes, with actuators as an invaluable device ensuring both safe and precise operation.

Tuesday, August 30, 2016

BIST (Built-in-Self-Test) Features for Electronic Valve Actuators

Limitorque
Electric actuator (Limittorque)
Abstract

The development and implementation of safety related devices in plant systems is crucial for dependable operation, not to mention peace of mind. Safety and safe operation were once only high priorities for installations that involve hazardous environments. Expensive certification testing was, and still is, paramount to meeting the hazards of such environments, but a new level of plant-wide integrity is emerging — that of Safety Integrity Level (SIL) and SIS. SIL is a safety rating that can be derived by analyzing a system to determine the risk of a failure occurring and the severity of its consequences. Safety Instrumented Systems (SIS) are systems containing instrumentation or controls installed for the purpose of preventing or mitigating a failure either by emergency shut down (ESD) or diverting the hazard. New or replacement equipment must have the ability to be introduced into plant systems without jeopardizing either the SIL of the operation or negatively impacting the SIS.

Read the entire white paper below.

For more information visit this link or contact:

Mead O'Brien
www.meadobrien.com
(800) 892-2769

Tuesday, February 23, 2016

Theory of Operation for MOVs (Motor Operated Valves)

Limitorque SMB MOV
Limitorque SMB MOV
This presentation, provided by the NRC, provides an introductory look at motor operated valves, with a focus on the manufacturer Limitorque. The document includes the theory of operation of MOVs, plus descriptions of valve types, such as gate, globe, ball, plug and butterfly.

This document also provides detailed descriptions of Limitorque SMB actuators and Limitorque SB actuators with full assembly and subassembly breakdown and illustrations.




Document provided by NRC.gov

Thursday, September 24, 2015

Product Update - New Valve Actuator Series From Limitorque

Limitorque Electric Valve Actuator CEA Series
New Limitorque CEA Series Valve Actuator
Courtesy Flowserve Corp.
Industrial process control encompasses a broad range of fluid handling operations. A significant part of fluid control is accomplished by valves, many of which are operated automatically through the use of actuators. Actuators are mounted on valves in place of, or in addition to, a handwheel, lever, or other manual means of opening and closing the valve. With an actuator installed, a control signal can be transmitted from a remote source to the actuator, commanding a change in valve position, and the actuator will respond by converting some form of connected energy into mechanical motion that positions the valve accordingly.

Modern actuators are increasingly endowed with functions that provide information to the process operator, closing the loop with feedback that confirms the valve position, suitability of the energy supply to the actuator, and a range of other specialized data points.

An eternal desire of all process operators is a reduction in whatever level of maintenance that is currently required to keep everything operating. Maintenance is costly and time consuming, a set of many specialized tasks, each with a probability of not being completed properly.

Flowserve Corporation, under their well known Limitorque brand, has designed and launched a new series of electric actuators, the CEA Series, that provide real benefits for operation and maintenance in light-to-medium duty applications. Some of the highlights....
  • Auto calibration and a user-friendly HMI provide optimized commissioning. Standard diagnostics include torque monitoring and actuator temperature, with early warning detection of undesirable conditions and an alarm output.
  • Application specific brushless DC motors and worm gear drives reduce downtime. Tests have demonstrated reliability of up to 250,000 cycles. Modulating service can provide 1800 starts per hour with 0.1% position accuracy.
  • Suitable for applications with rotary duty requirements of 90 and 180 degrees, as well as multi-turn duty to 20 turns.
  • Available through a network of professional industrial process control distributors, with application assistance and product expertise.
  • CEA is fully qualified to NEMA Type 4, 4X and6, IP66/68 Class 1, Div 1 and 2, Gps B,C,D (CSA,FM) and ATEX II 2G Ex d IIB +H2 T4: IECEx II 2G Ex d IIB +H2 T4.
The CEA actuator is available in seven sizes and five variants, serving torque requirements up to 15,000 in-lbs (1695 Nm). Contact a product specialist to find out more about this new product and discuss your potential applications.