The Rotork CP range is built for quarter-turn valve automation where reliability, high torque density, and predictable fail-safe behavior matter more than “pretty” hardware. CP actuators use a pneumatic scotch-yoke mechanism (symmetric yoke) and are offered in double-acting and spring-return versions. The compact layout is designed to deliver high torque even at low supply pressures, bringing heavy-duty actuator design concepts into smaller quarter-turn applications.
Rotork CP/S-035-080A/AL is a spring-return (fail-safe) configuration within the CP family. It is typically selected for automated ball valves, butterfly valves, and plug valves where you need the valve to move to a defined safe position on loss of air supply (fail-open or fail-close, depending on build). Rotork lists the CP range as suitable for on/off and modulating duties, and highlights certifications that are commonly required in process industries (IP, ATEX, PED, SIL).
1) Model Code Breakdown (What the Number Actually Means)
Rotork’s CP brochure includes a clear “Model Number Designation” section. Interpreting CP/S-035-080A/AL using that designation:
| Segment | Meaning | What it indicates for this model |
|---|---|---|
| CP | Compact Scotch Yoke (C) + Pneumatic supply (P) | A compact pneumatic scotch-yoke actuator family |
| /S | Execution type: S = Spring-Return | Fail-safe spring return actuator |
| 035 | Centre body size (nominal movement arm) | CP family body size 035 (one of 035/045/055/065) |
| 080 | Cylinder size | Cylinder size code 080 |
| A | Seals | A = NBR, temperature range -30 to +100 °C |
| /AL | Spring-return execution variant | AL–EL variants apply to spring-return 35/45 without spacer |
So, in plain engineering language: this is a CP spring-return actuator, size 035, cylinder size 080, with NBR seals (standard temperature band), built in an “AL” spring-return execution for the 35 frame without spacer.
2) What the CP Platform Is Optimized For
High torque in a compact envelope
The CP range is described as a modular scotch-yoke design aimed at producing surprisingly high torque even at low pressures, with design concepts derived from Rotork’s larger heavy-duty actuators.
Pressure, torque ceiling, and temperature bands (range-level)
Rotork’s CP sales brochure states the CP range is designed for:
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Operating pressure: up to 12 bar (174 psi)
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Torque output: up to 4,500 Nm
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Temperature ranges: Standard -30 to +100 °C, Low -40 to +100 °C, Extreme low -60 to +100 °C (and a note that higher temperature versions up to 160 °C require contacting Rotork)
That’s range-level capability, not a promise that every size hits the maximum torque—your exact output depends on the chosen size/cylinder/spring set.
3) Construction and Interfaces (Why it’s built the way it is)
Rotork calls out multiple design choices that directly influence service life and maintainability:
| Design area | What Rotork highlights | Practical value in the field |
|---|---|---|
| Mechanism | Pneumatic scotch yoke (symmetric yoke) | Strong breakaway torque characteristics; stable output profile for quarter-turn valves |
| Body / structure | Ductile cast iron actuator body (four sizes) | Strength-to-weight efficiency; robust housing for process environments |
| Cylinder corrosion protection | Corrosion resistant cylinders in electroless nickel-plated carbon steel | Better resistance to corrosion and wear, especially in humid or aggressive atmospheres |
| Accessory mounting | NAMUR topworks interface; valve interface conforms to ISO 5211 | Easy fitting of switch boxes/positioners; predictable mounting to valves |
| Sealing / environmental | Protection certified to IP66M / IP67M (brochure and product page) | Suitable for outdoor / washdown / harsh weather service when correctly installed |
For buyers, those interface standards matter because they reduce adapter complexity and shorten commissioning time—especially when you’re pairing the actuator with a NAMUR-mounted positioner and limit switch box.
4) Compliance and Risk-Control Features
Rotork lists a set of certifications and conformity claims on the CP product page:
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IP66M/67M certified
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ATEX 2014/34/EU certified
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Certified in accordance with PED 2014/68/EU
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Certified suitable for SIL3 use as a single device in accordance with IEC 61508
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Optional emergency manual override (operate actuator during loss of supply)
This combination is a strong fit for oil & gas, chemical, and other process facilities where the actuator is part of a safety-instrumented function, or where the area classification requires ATEX compliance.
5) Notes Specific to the 035-080 Family (Mounting / Connections)
Rotork’s CP/S dimensional data tables include the CP/S-035-080 family and show an ISO 5211 F07 mounting interface and 1/4" pneumatic connection designation for the listed 035-080 variants.
(Your exact configuration may differ depending on execution and options, but the 035-080 family data provides a reliable reference point for typical interfaces.)
6) Options and Typical Configurations
Rotork positions CP actuators as modular—meaning you can configure the same platform into different duty profiles. The brochure explicitly lists options such as:
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Integral / jackscrew manual override (can be fitted, including in the field)
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Control systems, custom adaptors, custom paint specifications
The product page also emphasizes spring-return configurations supporting fail close / fail open.
That makes CP/S-035-080A/AL appropriate when the process safety philosophy demands a defined state on loss of air—e.g., fail-close for isolating a line, or fail-open for venting or cooling flow (the correct choice is process-specific).
7) Selection Guidance (How to Specify Without Getting Burned)
A spring-return actuator selection is basically a torque and safety puzzle:
| Step | What to confirm | Why it matters |
|---|---|---|
| 1 | Valve breakaway / seating torque (worst-case) | Spring-return must overcome worst-case torque in the fail direction |
| 2 | Air supply pressure available (normal and minimum) | CP range supports up to 12 bar, but real plants have pressure drops |
| 3 | Fail-safe direction (fail-open vs fail-close) | CP/S supports both, depending on execution |
| 4 | Temperature and seal compatibility | Your model uses NBR (standard) unless you specify Viton/fluorosilicone variants |
| 5 | Accessory package (positioner, limit switches, solenoid, air set) | NAMUR/ISO interfaces simplify integration |
If you’re building SKUs for multiple markets, you’ll often want to keep the base actuator (CP/S-035-080…) constant while offering variants via seal type (A/B/C/E) and execution details, because those are the “real” differentiators in procurement specs.
8) Summary (One Paragraph You Can Reuse)
Rotork CP/S-035-080A/AL is a compact pneumatic scotch-yoke actuator in Rotork’s CP range, configured as a spring-return unit for quarter-turn valves. The code indicates a 035 body size with 080 cylinder size and NBR (A) seals suitable for -30 to +100 °C, with an AL spring-return execution used for 35/45 frames without spacer. The CP platform is designed for high torque density, modular accessory integration via NAMUR/ISO interfaces, and compliance-focused installations, with range capabilities including up to 12 bar supply pressure, IP66M/67M sealing, and certifications such as ATEX, PED, and SIL suitability (range dependent).
