Flowserve Rotadisk RD and RDF Pneumatic Actuator
Overview
The Flowserve Rotadisk is a quarter-turn pneumatic actuator supplied by Flowserve Flow Control GmbH, made for automating ball valves and other 90 degree valves. It comes in two types: the RD, a double-acting actuator driven by air in both directions, and the RDF, a single-acting actuator with spring return for a defined fail-safe position. Seven sizes, numbered 2.5 to 160, cover the range from small instrument-line ball valves to large process valves.
Seven Star LLC supplies the Flowserve Rotadisk to Oman and the GCC, with engineering support in Muscat. The Flowserve manual notes that Argus ball valves are often automated with a mounted pneumatic, hydraulic or electric actuator, and the Flowserve Rotadisk is the pneumatic option from the same manufacturer. If you are specifying a complete automated valve, see the Argus FK76M trunnion mounted ball valve as a mating valve.
Scotch-Yoke Working Principle
The Rotadisk uses a pneumatic twin-piston drive on the Scotch-Yoke principle. Two pistons act on a yoke that converts their straight-line travel into rotation of the transmission shaft. Because of the geometry, the available torque is highest at the end positions, which is exactly where a ball valve needs its breakaway and seating torque. Flowserve notes that the principle gives high torque from the smallest possible outer dimensions.
In the standard design the base position is closed, with clockwise rotation closing the valve as seen from above. An alternative design sets the base position to open, with the rotation direction reversed. On the RDF, the spring package returns the actuator to the base position when air is vented, so a loss of air supply moves the valve to its fail-closed or fail-open state. Spring packages run from -1 to -3, with intermediate -1.3 and -1.8 variants.
Engineering Design of the Flowserve Rotadisk
The Flowserve Rotadisk body is anodised aluminium alloy, with an aluminium alloy lid finished in multilayer PU paint, an aluminium alloy piston and a stainless steel transmission shaft. Permanent lubrication with ROCOL SAPPHIRE Lo-Temp 2 is specified. Adjustable end stops allow stroke limitation in the open position on all sizes except size 2.5, and the actuator rotates 90 degrees plus or minus 3 degrees.
Mounting follows standard interfaces: DIN/ISO 5211 and DIN 3337 for valves, VDI/VDE 3845 for signal devices and positioners, and Namur 1/4 inch for solenoid valves. A solenoid valve panel and threaded fastening holes make accessory fitting straightforward. The manual states that the Flowserve Rotadisk is suitable for use in explosive atmospheres in zones 1 and 2, because it has no ignition source of its own when used as intended.
Key Features
The Flowserve Rotadisk is built for compact, repeatable valve automation. Main features include:
- Double-acting RD and spring-return RDF types in seven sizes from 2.5 to 160.
- Scotch-Yoke twin-piston drive that delivers high torque at the end positions in a compact housing.
- Spring packages from -1 to -3 on the RDF, rated for 10 000 000 spring load cycles.
- Standard control pressure of 3 to 8 bar, with special versions up to 10 bar shown on the nameplate.
- Operating temperature of -20 to +80°C as standard, with low-temperature (-40 to +60°C) and high-temperature (-20 to +180°C) versions.
- Anodised aluminium body, aluminium piston and stainless steel transmission shaft for corrosion protection.
- Standard DIN/ISO 5211, DIN 3337, VDI/VDE 3845 and Namur interfaces for add-on devices.
- Suitable for dry filtered air, neutral gases such as nitrogen and CO2, or hydraulic oil as the control medium.
Industrial Applications
Flowserve intends the Rotadisk for actuating ball valves, globe valves, gate valves and check valves in on/off service. Typical uses in Oman include shut-off valves on gas and condensate headers, dosing-skid isolation in water treatment, and fuel and utility isolation in power and industrial plants around Sohar, Duqm and Salalah. The manual states clearly that the actuator is not intended for controlling flow volume, so modulating duty needs a different actuator and positioner combination.
The RDF fail-safe function is the reason many engineers select the Flowserve Rotadisk. A line that must close on loss of instrument air, such as a fuel gas supply or a chemical feed, uses a spring-closing RDF, while a cooling line that must stay open uses the spring-opening variant. Seven Star LLC can size the actuator size and spring package against valve torque and supply pressure, and can quote alternatives such as the Biffi ALGAS spring-return pneumatic actuator if a different mounting standard is preferred.
Technical Specifications
The table below summarizes the Flowserve Rotadisk RD and RDF as published in Flowserve manual AIIOM001063. Torque at each supply pressure is given in the manual appendix, for example 40 Nm for the RD 2.5 at 8 bar and 2560 Nm for the RD 160 at 8 bar.
| Parameter | Specification |
|---|---|
| Model | Flowserve Rotadisk RD (double-acting) and RDF (single-acting, spring return) |
| Sizes | 2.5, 5, 10, 20, 40, 80, 160 |
| Piston diameter | 40 to 165 mm |
| Stroke | 25 to 104 mm |
| RD weight | 0.85 kg (size 2.5) to 46.9 kg (size 160) |
| RDF weight | 1.15 kg (size 2.5) to 64.2 kg (size 160) |
| Control pressure | 3 to 8 bar standard, up to 10 bar special |
| Control medium | Dry filtered compressed air, nitrogen, CO2, hydraulic oil |
| Operating temperature | -20 to +80°C standard, -40 to +60°C low temperature, -20 to +180°C high temperature |
| Rotation | 90 degrees plus or minus 3 degrees, clockwise standard, anti-clockwise optional |
| Interfaces | DIN/ISO 5211, DIN 3337, VDI/VDE 3845, Namur 1/4 inch |
Documents and Ordering Notes
The attached file is the Flowserve installation, operation and maintenance manual for the Rotadisk RD and RDF (document AIIOM001063), not a one-page datasheet. It contains the technical data, torque tables, spring packages and maintenance procedures. When requesting a quotation, please state the valve torque, supply pressure, fail-safe direction and any required accessories.
Why Choose Seven Star LLC for Flowserve Rotadisk Supply
Choosing a quarter-turn actuator is a torque and air-supply calculation, and an undersized unit fails at the worst moment. Seven Star LLC checks the valve breakaway torque, the minimum supply pressure and the required safety factor against the torque tables in the manual before recommending a Flowserve Rotadisk size and spring package. We also confirm the mounting flange, the positioner and solenoid interfaces and the fail-safe direction, so the Flowserve Rotadisk you order arrives ready to bolt onto the valve and connect to your instrument air.
Request a Quote for Flowserve Rotadisk
To request a formal quotation for the Flowserve Rotadisk, check regional availability or obtain the manual, contact the instrumentation division at Seven Star LLC. We supply Flowserve valves and actuators to Oman and the GCC, and can quote the actuator together with the valve, positioner and solenoid accessories, or the Biffi F01 electric quarter-turn actuator where an electric actuator is preferred.
- Instruction Manual Flowserve Rotadisk RD and RDF Pneumatic Actuator Installation, Operation and Maintenance Manual Download
Flowserve product families listed here
Flowserve pumps on this page are the Durco Mark 3 ANSI process pump and the ECPJ vertical sump pump built to API 610 type VS4. Sealing products are the ISC2 cartridge mechanical seal to API 682 and DuraClear barrier fluid for dual seal systems. Flowserve valves include the Valtek Mark One globe control valve, Argus floating and trunnion-mounted ball valves (EK71, FK79, FK76M) and Durco Microfinish ball valves. Automation is covered by Limitorque MX and L120 multi-turn electric actuators, the Rotadisk RD and RDF pneumatic actuator and the Logix 3800 digital positioner.Where Flowserve equipment is used
Mark 3 pumps handle acids, caustic, solvents and utilities in chemical and petrochemical units. VS4 sump pumps drain pits and collection tanks. Valtek control valves and Argus ball valves are found in refining, gas processing, power and desalination, and Limitorque actuators operate gate and globe valves on pipelines, tank farms and water networks across the GCC.Ordering Flowserve parts: what we need
The serial number on the nameplate is the key to Flowserve records for a pump, valve or actuator. Please add the following by product type:- Pumps: size and model, impeller diameter, materials, seal arrangement, and the part name and item number from the sectional drawing
- Mechanical seals: seal type and size, drawing or part number, materials code, pumped fluid and flush plan
- Valves: size, pressure class, body and trim materials, end connections, and the actuator and positioner model
- Limitorque actuators: unit size, order and serial number, supply voltage, wiring diagram number
Browse Flowserve products by category: Control Valves, Pumps, Valve Actuator, Valve Positioner.
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