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Brand: Biffi
Biffi RPS Spring-Return Pneumatic Rack and Pinion Actuator
Description
Overview
The Biffi RPS is a spring-return (single-acting) pneumatic quarter-turn actuator of rack and pinion design. It belongs to the same series as the double-acting Biffi RPD. The manufacturer describes both as actuators for on-off and modulating control of valves in heavy duty service, designed to give maximum torque output with minimum supply pressure in any quarter-turn application such as ball, plug and butterfly valves or dampers. The series is available for output torques up to 3700 Nm.
The RPS is powered by a compressed gas supply in one direction and by a mechanical spring in the other. It is not an electric or electro-hydraulic unit and it has no motor, pump or oil reservoir. The supply medium can be air, nitrogen or sweet gas, and the design pressure (maximum allowable working pressure) is 12 barg maximum. Seven Star LLC supplies the Biffi RPS on request to buyers in Oman and the GCC, with lead time confirmed at quotation.
Operating Principle of the Biffi RPS
In the RPS a pneumatic piston is connected to a rack, and the rack meshes with a pinion on the output shaft. Supply gas admitted to the cylinder moves the piston, turns the pinion through 90° and compresses the spring at the same time. When the supply pressure is released, whether by a control command or by a supply failure, the spring pushes the piston back and returns the valve to its fail position. The model code ends in CL for spring to close or OP for spring to open, and the manufacturer states that the RPS can be mounted either way without modification.
The datasheet gives four torque values for each model: break and end torque for the spring stroke, and break and end torque for the air stroke at each supply pressure. It also gives a hold pressure, defined as the minimum pressure needed to operate the actuator.
Engineering Design of the Biffi RPS
The housing is weatherproof and totally enclosed, and on the RPS it is made of ductile iron or carbon steel. The shaft is nickel-plated alloy steel, the rack and pinion are ductile iron, and an adjustable bronze sliding block supports the rack to keep transverse forces low. The cylinder tube is nickel-plated carbon steel with a polished bore. The spring is carbon steel and the spring module is fully encapsulated, which the manufacturer states is for personnel safety and simpler assembly. Seals are NBR rubber as standard, with fluoroelastomer and fluorosilicone seals as an option.
Travel stop screws allow angular stroke adjustment of 90° plus or minus 4° at each end of travel. The RPS is listed in models 14-S1, 15-S2, 30-S2, 60-S2, 120-S2, 120-S2.4 and 120-S3, each with several spring types (A, B, C, D and J), so that the spring torque can be matched to the valve. A jackscrew manual override (MHW) can be fitted.
Key Features
The following features are stated by the manufacturer for the RPD and RPS series.
- Fully encapsulated RPS spring module for personnel safety and simpler assembly.
- Mountable as spring to close or spring to open without modification.
- Weatherproof, totally enclosed housing in ductile iron or carbon steel.
- Constant output torque from the rack and pinion mechanism throughout the 90° stroke.
- Adjustable bronze sliding block and nitrided rack for low transverse forces and minimal friction.
- Angular stroke adjustment of 90° plus or minus 4° at each end of travel.
- Electroless nickel-plated polished cylinder and floating-type piston seals with low hysteresis.
- Lever or jackscrew manual override, an extensive range of accessories, and special coatings for offshore or corrosive environments.
Industrial Applications
The Biffi RPS is used where a quarter-turn valve or damper must move to a defined position when the pneumatic supply or the control signal is lost. Typical duties are fail-close or fail-open isolation valves and modulating control valves of ball, plug or butterfly type in process plants, utilities and pipeline installations.
For safety-related and hazardous-area service, the datasheet lists suitability for use in SIL 3 applications to IEC 61508, ATEX area classification II 2 GD, and enclosure ratings IP66, IP66M and IP67M to IEC 60529 and NEMA 4, 4X and 6. Where no spring-driven fail action is needed, the double-acting Biffi RPD is the corresponding model.
Technical Specifications
The table below summarizes the main data for the Biffi RPS, taken from Biffi product data sheet VCTDS-02813-EN Rev. 4 (June 2023).
| Parameter | Specification |
|---|---|
| Model | Biffi RPS (spring-return pneumatic) |
| Actuator Type | Pneumatic rack and pinion, quarter-turn (90°), single-acting |
| Fail Action | Spring to close (CL) or spring to open (OP) |
| Supply Medium | Air, nitrogen or sweet gas |
| Design Pressure (MAWP) | 12 barg maximum |
| Maximum Operating Pressure | 5 to 12 barg, depending on model |
| Output Torque | Up to 3700 Nm (series) |
| Standard Temperature Range | −20°C to +100°C |
| Extended Temperature Range | −60°C to +135°C |
| Stroke Adjustment | 90° ± 4° at each end of travel |
| Models | 14-S1, 15-S2, 30-S2, 60-S2, 120-S2, 120-S2.4, 120-S3 |
| Enclosure Protection | IP66, IP66M, IP67M; NEMA 4, 4X, 6 |
| Approvals | ATEX II 2 GD; suitable for SIL 3 applications (IEC 61508); PED 2014/68/EU; Machinery Directive 2006/42/EC |
| Manual Override | Lever or jackscrew (MHW), optional |
| Valve Compatibility | Ball, plug and butterfly valves, dampers |
Request a Quote for Biffi RPS Spring-Return Pneumatic Rack and Pinion Actuator
To request a quote for the Biffi RPS, send Seven Star LLC the valve type and size, the required break and end torques with safety factor, the fail action (spring to close or spring to open), the available supply pressure and medium, the ambient temperature range and any accessories needed. The actuator is supplied on request, with lead time confirmed at quotation.
Browse the full Biffi range or see more Valve Actuator products supplied by Seven Star LLC in Oman and the GCC.
Datasheets & Documents
- Datasheet Biffi RPD / RPS Pneumatic Actuators Datasheet Download
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About brand
Biffi is an Italian maker of valve actuators for the oil and gas and petrochemical industries. Its first factory opened in 1955 in Fiorenzuola d'Arda, near Piacenza, making electric actuators for the Italian petrochemical industry; the company moved to its present site in 1969. Biffi is now part of Emerson, and its pneumatic, hydraulic and electric actuators drive pipeline, wellhead and shutdown valves.
Seven Star LLC lists Biffi actuators across these operating media and supplies them to valve automation shops and operators in Oman, sized from the valve torque data.
Biffi company profile
| Founded | 1955, Fiorenzuola d'Arda, Italy |
|---|---|
| First products | Electric valve actuators for the Italian petrochemical industry |
| Headquarters | Fiorenzuola d'Arda, Piacenza, Italy (Biffi Italia Srl) |
| Ownership | Emerson |
| Product families | ALGA pneumatic scotch-yoke actuators, ALGAS gas-over-oil actuators, F01 and ICON2000 electric actuators, electro-hydraulic and hydraulic actuators for on-off and emergency shutdown duty |
Milestones
- 1955: The first Biffi factory opens in Fiorenzuola d'Arda.
- 1969: Biffi moves to its present location.
- 1978 and 1996: The plant is expanded.
Biffi actuator series on this page
The series names follow a logic that helps when reading a tag. ALGA is the pneumatic quarter-turn actuator and ALGAS its spring-return version. OLGA-H is the hydraulic quarter-turn actuator and OLGAS-H the fail-safe hydraulic version with spring. In the compact rack-and-pinion group, RPD and RPS are the double-acting and spring-return pneumatic pair, and RPHD and RPHS are their hydraulic counterparts. The F01 and F02 are electric quarter-turn actuators, the ICON2000 and ICON3000 are electric multi-turn actuators and the EFS 3000 is a fail-safe electric quarter-turn actuator; the manufacturer now names the Bettis SCE300 as the replacement for the F02. In each pair the S marks the model that returns to a safe position by spring.
Where Biffi actuators are used
Typical duties are emergency shutdown and blowdown valves, pipeline block valves, wellhead and manifold valves, tank farm isolation and large ball valves at compressor and metering stations. Spring-return models are chosen for fail-safe service. Hydraulic and electro-hydraulic units appear where instrument air is not on hand, as on remote GCC pipeline stations.
Biffi products we list
Ordering Biffi actuators: what we need
Actuators are sized, so the valve data comes first: valve type and size, the torque curve or at least break, run and end torques, the safety factor in your specification and the stem and mounting flange dimensions. Then the supply: minimum and maximum air or oil pressure, or voltage for electric units. State the fail action, stroking time, ambient temperature and the control accessories required. For an existing actuator send the model and serial number from the nameplate.
Facts checked against Biffi's own history (Emerson), October 2026.
Browse Biffi products by category: Valve Actuator.
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Frequently Asked Questions
How is the Biffi RPS different from the RPD?
Both are pneumatic rack and pinion quarter-turn actuators from the same series. The RPD is double-acting, so the supply gas drives it in both directions. The RPS is spring-return: the supply gas drives one stroke and compresses a spring, and the spring drives the return stroke when the pressure is released or lost.
What supply does the Biffi RPS need?
The RPS needs a compressed gas supply. The manufacturer datasheet lists air, nitrogen or sweet gas as the supply medium, with a design pressure of 12 barg maximum. Each model has a hold pressure, the minimum pressure needed to operate the actuator, and a maximum operating pressure. No hydraulic power unit or electrical supply is needed for the actuator itself.
Can the RPS be spring to close or spring to open?
Yes. The manufacturer states that the RPS can be mounted as spring to close or spring to open without modification. The fail action is shown at the end of the model code, CL for spring to close and OP for spring to open. The same torque table is used for both arrangements, with the break and end values exchanged.
How is the right RPS model selected?
Selection is based on the valve torque at the break and end positions, for both the spring stroke and the air stroke, and on the supply pressure available. The datasheet lists these four torque values for each model and spring type, together with the hold pressure and the maximum operating pressure. Several spring types are offered for each actuator size.
How does Seven Star LLC supply the Biffi RPS?
Seven Star LLC supplies the Biffi RPS on request to buyers in Oman and the GCC. Lead time is confirmed at quotation. To prepare a quote we need the valve type and size, the required torques, the fail action, the available supply pressure and medium, the ambient temperature range and any accessories required.
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