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Control, On-Off Ball, Gate, Globe and Butterfly valves all
require a mechanism to actually “drive” them, this is what is called an
“Valve Actuator”. These Valve Actuators come in various forms, and use
various power sources as an operating medium. Typically the power sources
utilised by the Instrument and Control System design engineers is pneumatic,
hydraulic and electrical. Of course the most basic actuator is a manual hand
Design of the
Valve Actuator - The design engineer has to consider the operating conditions
1. The atmosphere and
potential corrosion. If the Actuator is being utilised on an Offshore Platform
or FPSO then particular care must be taken in selecting the actuator body
materials and internal mechanism. Particular emphasis on this should be taken on
the tubing associated with pneumatic actuators or any that ‘breathe’ on the
return stroke, potentially sucking in salt or corrosive air into the
internal mechanism. Under this scenario a technique called closed loop
breathing is used (an excellent schematic of a typical system can be found here).
Selection of any accessories such as quick exhaust, solenoid valves and limit
switches etc must also consider the conditions. In the Offshore Oil and Gas
Industry 316SS Actuators are sometimes selected.
2. Torque requirements
must be carefully considered as too little power can mean that any stiction in
the valve means that the valve may stick in the cycle. Too much power may
actually cause the valve mechanism to shear.
3. Pneumatic Valve
actuator 0 – 100% cycle may be various pressures, control valve actuators are
generally 3 – 15 psi (20 – 100kpa). However they may sometimes be set
differently to this.
4. On – Off Valve
Actuators may be set to other pressures, commonly 0 to 100 psi, this is to keep
the size of actuator as compact as possible.
5. Hydraulic Valve
Actuators utilise much higher pressures, especially on very large ball valves,
this design is used to obtain the higher torques required and to keep the
actuator and valve footprint as compact as possible.
6. Smart Positioners
may be used both on Control and On – Off Actuator Valve combinations, these
are a superb maintenance tool in that the Valve/Actuator signature at new
conditions can be taken. Any changes outside parameters then mean that any
maintenance is condition based.
ACT Actuators accommodate a specific market need for a compact spring return actuator to operate quarter turn and linear operated valves. Applications that particularly benefit from their compact design are those where installation space is limited, like on topsides, high-pressure manifolds, internal / external turret areas and (vertical mounted) riser valves. A compact actuator design could also benefit the handling, mounting and alignment in case large valve sizes/high pressure ratings do apply. Due to the enhanced actuator design, ATC actuators are also installed in shallow to ultra deepwater, and available complete with ROV interfacing and receptacles to ISO. ATC actuators are SIL 3 compliant to IEC 61508 and are manufactured in compliance with the ISO 9001 2000 quality procedures.
Compact Actuator Solutions and Systems - Some comprehensive Compact Actuator Design Information and Application details from Prochem.
Compactness - Design flexibility, combined with the innovative integration of all actuator parts, results in the most compact actuator available in the market. In virtually all applications, irrespective of hydraulic or pneumatic supply, the ATC actuator diameter is smaller than the Face-to-Face dimension of the valve. The ATC actuator enables designers to minimize overall dimensions, reduce platform weight & deck load and ease the design of steel support structures.
Performance - ATC compact actuators are based on an advanced compact
design with a revolutionary self-lubricating, low-friction torque conversion
mechanism which eliminates the risk of any mechanical wear and tear.
- Due to its innovative yet simple design, the ATC compact actuator is
based on a minimum number of parts. As a result, maximum reliability is
ensured throughout our entire range. ATC compact actuators are hermetically
sealed, airtight and watertight under all conditions.
Cost Savings for Contractors and Operators - Contractors can benefit directly from using ATC compact actuators, both at the FEED stage and the EPC(I) stage. The number of engineering hours (e.g. for piping lay-out) has been reduced drastically on a considerable number of projects. ATC compact actuators also make it possible to cut material costs and weight thanks to an optimised and shortened piping lay-out. In addition due to the nature of the design, no specific maintenance programs are required on ATC actuators during the lifespan of your project. Consequently, ATC compact actuators result in maximum availability at lowest operational cost without requiring periodic maintenance – not even actuator replacement!
Actuator Technical Features - ATC has a complete line of sub-sea
actuators available suitable for shallow water applications and installation in
ultra deep waters, including ROV interfacing. This includes Submerged production, Submerged (off) loading, Sub Surface Isolation Valve
PLEMS , Subsea Manifolds, Production Valves, Pipeline Valves, and Pigging
Subsea Quarter Turn
- Topsides / Manifolds, FPSO Turrets, Loading Buoys, Riser Valves, Isolation Valves,
and Ballast Valves
Upstream Quarter Turn Hydraulic
Upstream Quarter Turn Pneumatic
of Compact Actuators on High Pressure Manifolds –
Space and Weight are an important consideration when designing Valving and their
associated actuators on High Pressure Manifold Systems. Actuators which can be
installed in different angles provide significant advantages. By utilizing
Compact Actuators a “minimum design footprint” can be achieved.
for Safety Related Systems - The ATC spring return actuator
offers an enhanced reliability, while having a minimum quantity of actuator
parts. A complete FMECA has been carried out in conjunction with a complete
review of our installed base. The actuator is certified
by TUV Rheinland to meet SIL 3, following IEC 61508 and based on a 1oo1
Applications - Overpressure Protection Systems, HIPPS, and ESDV
Spring Return Hydraulic Actuator Technical Features - The standard ATC spring return actuator is the most compact actuator available in the market. In short, the ATC actuator offers the following advantages...
Spring Return Pneumatic Actuators Technical Features - Due to the innovative design, The ATC pneumatic spring return actuator is available in dimensions which are close to the hydraulic version and therefore uniquely compact.
Compact Double Block & Bleed (DBB) Valve Actuator Technical Features - The ultra compact ATC actuator allows for “redundant actuation” within one valve body (DBB) rather than using 2 individually installed valves. This optimisation results in a considerable reduction in pipe length, flanges, adapter sets and having the most impact in case exotic pipe materials are applied.
Double Acting Actuator Technical Features - The ATC double acting actuator is based on the same unique design approach and flexibility as applies to the spring return range.
Vessel Design Requires the Latest Weight and Space saving Concepts -
Space and weight saving on FLNG facilities are an essential design parameter as
“real estate” is very limited. Hence Compact Actuators are an important
component in achieving this design goal and have been utilised in major projects
around the world. Also whilst space and weight are paramount the additional
savings associated with Passive Fire Protection add to the overall justification
and use of these products.
Actuator - Actuators are used for the automation of industrial valves
and can be found in all kinds of technical process plants: they are used in
waste water treatment plants, power plants and even refineries. This is where
they play a major part in automating process control. The valves to be automated
vary both in design and dimension. The diameters of the valves range from a few
inches to a few meters. Depending on their type of supply, the actuators may be
classified as pneumatic, hydraulic, or electric actuators - This link from
Wikipedia gives lots of technical information.
General notes for the Calculation and Selection of Actuators - These general notes from Samson Controls are useful.
Descriptive Defini tion of Valve Actuators
tion of Valve Actuators- Chris Warnett -
Scotch Yoke - The Scotch Yoke principle is characteristic for its high torque when required - at the beginning and end of each operation. This increases safety, especially in applications where the valve remains stationary throughout long periods. From our sponsor Austral Powerflo Solutions and Remote Control.
Scotch Yoke or Rack-and-Pinion Pneumatic Part-turn Actuator? - Günter Öxler - This article reports on the best choice between the different technical solutions offered by pneumatic part-turn actuators - from Valve World.
Firesafe Actuators - Thanks to Samson Controls
EN 15714-1:2009 - Industrial valves - Actuators - Part 1:
Terminology and definitions
EN 15714-2:2009 - Industrial valves - Actuators - Part 2: Electric actuators for industrial valves - Basic requirements
EN 15714-3:2009 - Industrial valves - Actuators - Part 3: Pneumatic part-turn actuators for industrial valves - Basic requirements
EN 15714-4:2009 - Industrial valves - Actuators - Part 4: Hydraulic part-turn actuators for industrial valves - Basic requirements
Hydraulic Actuator Design and Operation - Pneumatic actuators are normally used to control processes requiring quick and accurate response, as they do not require a large amount of motive force. However when a large amount of force is required to operate a valve hydraulic actuators are normally used - from Engineers Edge
Control Valve Actuators - Their Impact on Control and Variability - Chris Warnett - Electric control valve actuators provide excellent performance and are ideal for oil and gas wells in remote production fields. Instrument air supply systems are costly and require significant energy to run. If mains power isn’t available, an instrument air supply isn’t practical, especially when only a few control valves are in use at a location. Solar powered DC electric actuators are ideal for such an application - from Rotork.
How Electric Control Valve Actuators Can Eliminate The Problems of Compressed Air as a Power Medium - Today, a new major technological advance is available that can help control-valve users avoid many of the problems and inefficiencies associated with using compressed air as a power medium. The new solution uses electric power and eliminates dependence on compressed air. This totally electric solution is appropriate and cost-effective for a wide variety of control-valve applications, including those found in such sectors as power generation, chemical, petrochemical, and most other process industries. While the new generation of electric control-valve actuators may not be suitable for all process applications, it is ideal for many situations, especially where users have experienced problems with frozen air hoses, lack of process precision, stick slip, and so on. Therefore, it is prudent for today’s process control engineers to take a serious look at how the design features of the new generation of totally electric control-valve actuators can benefit them - from Rotork.
Specification - Electric Valve Actuators in Water and Wastewater Treatment Plants - This is a typical specification from Auma Actuators, whilst product specific it is a useful basis for developing a specification.
Guidelines for the Specification of Electric Valve Actuators - This draft standard provides general requirements for the development of specifications for electric actuators - from the ISA.
Specification for Electric Actuators – Integral Motor Control - This
is a typical specification from Rotork Actuators, whilst product specific it is
a useful basis for developing a specification.
The Fisher Control Valve Handbook- This superb 295-page PDF whitepaper is a control valve resource that has been consistently updated for 30 years. It contains vital information on control valve performance and latest technologies. Thanks to Emerson Process Management
Understanding Control Valve Bench Set - Dave Harrold-from Control Engineering
Actuator and Control Valve Selection - Professor Dae Ryook Yang - Dept. of Chemical and Biological Engineering Korea University
Control Valve Actuators and Positioners - Control valves need actuators to operate. This tutorial briefly discusses the differences between electric and pneumatic actuators, the relationship between direct acting and reverse acting terminology, and how this affects a valve's controlling influence. The importance of positioners is discussed with regard to what they do and why they are required for many applications-from Spirax Sarco
Control Valve Actuator Options - Today’s Actuators Offer Imposed Performance With Lower Life-Cycle Costs. The Challenge Is Choosing the Right One for the Application - George Ritz - Over the past several years, valve actuators have received relatively little attention while process control specialists concentrated on controllers, sensors, and other components of the control loop. This is borne out by the unglamorous nickname “pig iron” assigned to the actuator/control valve unit. With the onset of the smart-valve generation, it suddenly appears that the control valve actuator may get more respect along with its new electronics degree - from CCI
Linear Pistion Actuators - Samy, Stemler - High Reliability of actuation is of paramount importance in the nuclear power industry. Pneumatic actuators form the largest installed base with many in safety significant applications. This paper addresses the issues related to actuation, such as available Thrust, Stiffness, Sensitivity, Hysteresis, Dead band, Dynamic Stability and a sizing example. This paper also presents comparisons between various types of linear actuators and their relative advantages and disadvantages. Also presented will be evaluation techniques for troubleshooting actuator problems and improving plant performance - from CCI
Valve Actuators: Their Impact on
Control and Variability - Chris
Warnett, In a process plant, the general function of a control valve is to
restrict the opening of the valve so it affects the flow or pressure of the
liquid or gas that is passing through it. In any given
application, an installed valve, whether it is a rotary or sliding stem valve,
has one fundamental variable - the position of the moving element. That single
moving element determines the exposed orifice that allows greater or lesser flow
through the valve, which in turn
provides the control of the process.
11.13 Closed Loop Breathing - This is a technique to ensure that corrosive or saline air cannot enter the internals of the valve on the breathing side of the valve. It is very popular in the Offshore Oil and Gas Industry and on Coastal Refineries etc - thanks to Rotork for this excellent schematic.
The following links are provided thanks to ICEweb Sponsor Austral Powerflo Solutions
Rotary Limit Switch Boxes - Rotary limit switch boxes provide a visual and remote electrical indication of quarter turn valve/actuator position (ball, butterfly and plug).
Bolt Switches - "Bolt" switches are magnetic proximity switch suitable for any type of position indication.
Valve Position Indicators - The 3D Series namur indicators provide high visibility verification of valve/actuator position. The indicator features a rotor with red and green quadrants that rotate to indicate valve open and valve closed positions.
Override - Declutchable gear overrides are used for manually operate valve
complete of double acting or spring return actuators.
Spring Return Cartridges - Spring return cartridges are used on manually operated valves to ensure that a fail safe position is achieved. The lever or hand wheel is used to manually operate the valve and when the operator releases the lever or hand wheel the spring return cartridge will automatically stroke the valve to the failsafe position.