Bettis CBB-Series Scotch Yoke Pneumatic Actuator

Overview

The Bettis CBB-Series is the latest generation of Emerson’s compact pneumatic scotch yoke actuators, developed from the earlier Bettis CB and CBA designs. It keeps the same envelope dimensions and mounting interfaces as previous CB versions, so existing installations can be upgraded without changing brackets or couplings, while adding an improved torque shaft seal, a revised travel stop design and easier field upgrades for high temperature service. The series automates ball, butterfly and non-lubricated plug valves, or any other 90 degree rotating mechanism.

Seven Star LLC supplies the Bettis CBB-Series to plants and project contractors in the Sultanate of Oman and throughout the GCC. As a trusted supplier with engineering support in Muscat, we help maintenance teams replace older CB actuators like for like and help new projects select the right size and spring package from the 29 available configurations.

Operating Principle

The Bettis CBB-Series converts the linear motion of an air-driven piston into quarter-turn rotation through a scotch yoke mechanism. The output torque is highest at the beginning and end of travel, which corresponds to the breakaway and reseating points of most quarter-turn valves. Emerson notes that both the double-acting and single-acting (spring-return) versions have no external moving parts other than the position indicator, which improves safety and keeps routine maintenance to a minimum.

Spring-return Bettis CBB-Series units act as the fail-safe link in a shutdown system: when the air supply fails or is vented, the spring automatically drives the valve to its safe closed or open position. CBB spring-return actuators are offered with four spring configurations to cover a wide range of torque requirements at different supply pressures, and each carbon steel spring is protected by Tactyl 50, a pliable self-healing coating that extends cycle life.

Engineering Design of the Bettis CBB-Series

The Bettis CBB-Series housing and piston are available in ductile iron or carbon steel, finished with a two-component polyurethane paint system for harsh environments. A ductile iron piston is standard, which allows simple upgrade to high temperature trim in the field. Inside the power cylinder, an optional Xylan fluoropolymer coating improves efficiency and resistance to abrasion and thermal shock. Water ingress is prevented by a separate pressure seal and weather seal between the torque shaft and housing, giving dual redundancy, and the actuator is independently certified to IEC 60529 IP66 and IP67M.

On the Bettis CBB-Series, a standard dual valve mounting interface allows installation in a fail-open or fail-close arrangement without disassembling the actuator, and the unit can be mounted in any position, parallel or at right angles to the flow line, vertically or horizontally. Integral bidirectional travel stops adjust from 80 to 100 degrees, and optional extended travel stops allow full stroke adjustment. Overrides include a blowout-proof jackscrew with hex nut or a jackscrew with handwheel for repositioning the valve after loss of supply.

Key Features

Engineers typically select the Bettis CBB-Series for the following design strengths.

• Twenty-nine sizes with guaranteed minimum torque up to 1,301 Nm (11,515 lb-in) double-acting and 482 Nm (4,269 lb-in) spring-return.
• Same envelope dimensions and mounting interfaces as earlier CB actuators for drop-in replacement.
• Separate pressure and weather seals on the torque shaft give redundant protection against leakage and water ingress.
• Ductile iron or carbon steel housing and piston provide strength, durability and corrosion resistance.
• Standard, high temperature and cold temperature trims cover ambient extremes from -40 to +177 °C.
• Dual valve mounting interface supports fail-open or fail-close installation without disassembly.
• FMEDA reporting through exida and compatibility with SIL-certified FIELDVUE controllers support partial stroke testing.
• Emerson backs the CBB with a five-year warranty on materials and workmanship.

Industrial Applications

Because it shares mounting dimensions with the established CB range, the Bettis CBB-Series is widely used for brownfield replacement in oil and gas production stations, refineries and petrochemical complexes where many CB actuators are already installed. Typical duties include on-off ball valves on process and utility lines, fail-safe shutdown valves on fuel gas and hydrocarbon systems, and automated butterfly valves in water injection, cooling water and fire water networks. Emerson lists oil and gas, power generation, pulp and paper, petrochemical, chemical, wastewater and nuclear industries among its users.

For coastal and desert sites, the closed loop instrument system recommended by Emerson routes exhaust air to the vented side of the cylinder to keep humid, salty or dusty air out. Seven Star LLC supports operators in Muscat, Sohar, Duqm and the GCC as a trusted supplier of the Bettis CBB-Series, supplying actuators with matched solenoid valves, limit switch boxes and positioners as complete packages.

Technical Specifications

Key Bettis CBB-Series data from the Emerson brochure and technical data sheet are summarised below.

How to Order

To obtain a quotation for the Bettis CBB-Series, share the valve data, existing actuator model if replacing a CB unit, supply pressure and fail position with Seven Star LLC. Our instrumentation team in Muscat confirms sizing against Emerson torque charts and prepares a complete actuated valve offer with lead time confirmed at quotation. Download the CBB brochure from this page, and see related items including the Fisher FIELDVUE DVC2000 digital valve controller, the ASCO 8210 Series solenoid valve and the Fisher 1061 pneumatic piston rotary actuator. Contact us for Bettis actuator supply across Oman and the GCC.