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Description

The Bettis RPC450-SR4 is a pneumatic rack and pinion rotary actuator in the RPC-Series, manufactured by Bettis (Emerson). It is designed to operate quarter-turn valves including ball, butterfly, and plug valves. This part is also referenced without the dash as RPC450SR4. Refer to manufacturer documentation to confirm compatibility with your specific application.

This actuator uses a rack and pinion mechanism to convert linear pneumatic force into ninety (90) degrees of rotary output, and is configured as a spring-return (fail-safe) unit — the "SR" designation confirms spring-return operation, and the "4" indicates the spring set configuration. Maximum operating pressure is One Hundred Twenty (120) PSI (8.5 BAR). The actuator produces both a pressure stroke (pneumatic) and a spring stroke (fail-safe return), with torque output varying across the stroke per the RPC-Series torque tables.

The RPC-Series was discontinued by Emerson/Bettis in 1998. The Quadrant C-Series (specifically the C450) is a recognized direct replacement, requiring no changes to mounting hardware, limit switch type, or air supply connections. Seal kits and service kits for the RPC-Series remain available from aftermarket suppliers to extend service life.

Technical Specifications

Brand: Bettis (Emerson)
MPN: RPC450-SR4
Alternate MPN: RPC450SR4
Type: Pneumatic Rack and Pinion Rotary Actuator
Series: RPC-Series
Actuation Type: Pneumatic
Operation: Spring Return (Fail-Safe)
Spring Configuration: SR4 (4-spring set)
Rotation: 90 Degrees (Quarter-Turn)
Maximum Operating Pressure: 120 PSI (8.5 BAR)
Compatible Valve Types: Ball, Butterfly, Plug (Quarter-Turn)
Product Status: Discontinued by Manufacturer
Direct Replacement: Quadrant C450 (C-Series)
Country of Origin: United States

Condition: New — Open Box. Sourced from manufacturing MRO turnover, plant closures, and industrial surplus; the part is new and unused but may have been in storage for years. Packaging may show shelf wear or be missing.

Shipping & Handling

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Returns

We offer free returns through eBay's standard 30-day return policy. If something isn't right, message us first — we want to make it right and we'll work with you to do it.

About ACME MRO Solutions

We started ACME MRO Solutions to fix something we kept running into as contractors — plants down, parts slow, surplus listings you couldn't trust. Our goal is simple: get YOU the right component fast, with an honest description, so you can get back to running.

We describe what we see. Used items show signs of use; if a part has visible wear, damage, or a missing component, the condition description will say so. We don't claim anything is tested unless we tested it — and we don't bench-test parts where testing isn't practical or revealing (feed-through modules, breakers, mechanical components). When we do test something, we'll say so explicitly.

If something is our fault, we don't work through it — we make it right. We are proud to serve American manufacturing. Your uptime is our bottom line.

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Questions? Talk to us.

Send a message through eBay. During business hours we typically respond within the hour. Whether you need to confirm compatibility before buying, request additional photos, ask about a cross reference, or work through something after delivery — message first and we'll figure it out together.