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Showing posts with label Blue Ribbon Parts & Service. Show all posts
Showing posts with label Blue Ribbon Parts & Service. Show all posts
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.
Limitorque factory trained technicians, support and parts. It's only factory authorized when the work is done by a Blue Ribbon Repair Center.
Your Limitorque actuators were a major investment. Don't take chances with an unknown. Choose only a Flowserve Limitorque Blue Ribbon Distributor to assure you're getting factory authorized service. It's just not worth the risk.
More than 1 million Limitorque actuators have been installed around the world, and some have been in operation for more than 50 years. The ruggedness and reliability of Limitorque electric actuators are among the primary reasons that customers continue to select Limitorque products.
Actuators requiring 90° of rotation to operate are necessary for quarter-turn valves such as ball, butterfly, plug and dampers, and rotary control valves. These types of Limitorque electric actuators are available for operations such as open-close, modulating, network and rotary service.
Multi-turn actuators are required to operate various types of rising stem valves such as gate, slide-gates, globe, check and linear control valves. These types of Limitorque electric actuators are available for operations such as open-close, modulating, network and linear service.
General Safety Precautions
Warning: Read the Installation and Maintenance Manual carefully and completely before attempting to install, operate, or troubleshoot the Limitorque actuator.
Warning: Be aware of electrical hazards. Turn off incoming power before working on the actuator and before opening the switch compartment.
Warning: Potential HIGH PRESSURE vessel — be aware of high-pressure hazards associated with the attached valve or other actuated device when installing or performing maintenance on the actuator. Do not remove the actuator mounting bolts from the valve or actuated device unless the valve or device stem is secured or there is no pressure in the line.
Warning: For maintenance and/or disassembly of the actuator while installed on the valve, ensure that the actuator is not under thrust or torque load. If the valve must be left in service, the valve stem must be locked in such a way as to prevent any movement of the valve stem.
Warning: Do not attempt to remove the spring cartridge cap, housing cover, or stem nut locknut from the actuator while the valve or actuated device is under load.
Warning: Do not manually operate the actuator with devices other than the installed handwheel and declutch lever. Using force beyond the ratings of the actuator and/or using additive force devices such as cheater bars, wheel wrenches, pipe wrenches, or other devices on the actuator handwheel or declutch lever may cause serious personal injury and/or damage to the actuator and valve.
Warning: Do not exceed any design limitations or make modifications to this equipment without first consulting Limitorque.
Warning: Actuators equipped with electrical devices (motors, controls) requiring field wiring must be wired and checked for proper operation by a qualified tradesman.
Warning: Use of the product must be suspended any time it fails to operate properly.
Caution: Do not use oversized motor overload heaters. Instead, look for the cause of the overload.
Caution: Do not operate the valve under motor operation without first setting or checking the limit switch setting and motor direction.
Caution: Do not force the declutch lever into the motor operation position. The lever returns to this position automatically when the motor is energized.
Caution: Do not depress the declutch lever during motor operation to stop valve travel.
Caution: Do not use replacement parts that are not genuine Flowserve Limitorque parts, as serious personal injury and/or damage to the actuator and valve may result.
Caution: Do not lift actuator/gearbox or actuator/valve combinations with only the eye bolts in the SMB actuator. These eye bolts are designed for lifting the SMB actuator only.
General Safety Practices
The following check points should be performed to maintain safe operation of the actuator:
Eye bolts in SMB and SB actuators are designed for lifting only the actuator and not associated gearboxes or valves.
Mount the actuator with the motor in a horizontal plane, if possible.
Keep the switch compartment clean and dry.
Keep the valve stem clean and lubricated.
Set up a periodic operating schedule for infrequently used valves.
Verify all actuator wiring is in accordance with the applicable wiring diagram.
Carefully check for correct motor rotation direction. If the valve closes when open button is pushed, the motor leads may have to be reversed.
Verify the stem nut is secured tightly by the locknut and that the top thread of the locknut is crimped or staked in two places.
Use a protective stem cover. Check valve stem travel and clearance before mounting covers on rising stem valves.
Mead O'Brien Authorized
Blue Ribbon Limitorque Parts & Service
For more information, or if you need field support with any Limitorque actuator, parts, or service, contact one of the following Mead O'Brien offices:
