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Scotch Yoke Pneumatic Actuator Lomas

The scotch yoke pneumatic actuators offer high-performance valve automation for quarter-turn valves such as butterfly valves, ball valves, and plug valves. Both double-acting and spring-return models are available to suit various application requirements.

Key features and advantages include:

• Scotch yoke mechanism provides high torque output and efficiency
• Rolling friction design minimizes wear for long service life (1,000,000+ cycles)
• Compact and lightweight compared to rack & pinion actuators
• Lower air consumption for energy savings
• Fast and precise valve control with adjustable stroke time
• Modular design with ISO 5211 mounting for installation flexibility
• NAMUR accessory interface, visual position indication
• Suitable for general industrial and harsh environments
• SIL 2/3 capable for safety applications
• Optional manual override and locking mechanism

The actuators use a scotch yoke to convert linear piston motion into 90° rotation. Precision-machined yoke, shaft and guides enable efficient and stable power transmission. Double-acting models use air pressure to drive the actuator in both directions. Spring-return models use air to drive in one direction and spring force to return the valve to a fail-safe position on loss of air supply.

Specifications:

• Torque range:
  • Double-acting: 15 to 5333 N•m
  • Spring-return: 15 to 451 N•m (maximum, varies by spring)
• Operating pressure: 2.5 to 8 bar
• Temperature range: -20°C to 80°C standard, -40°C to 150°C optional
• Angular rotation: 90° ±5°
• Output flange: ISO 5211 F03 to F25
• Air connections: NPT
• Cycle time: 0.25 to 3.0 sec depending on model
• Materials:
  • Body: Aluminum alloy
  • Shaft and yoke: Carbon steel or stainless steel
  • Seals: NBR, FKM
• Coating: Powder epoxy, RAL colors
• Protection: IP67, NEMA 4/4X, optional explosion-proof

Double-acting models range in size from DA40 (15 Nm) to DA260 (5333 Nm). Spring-return models range from SA60 (15 Nm) to SA260 (451 Nm). Refer to the specification tables for torque outputs at different supply pressures.

Installation dimensions for each model are provided in the outline drawings. Actuator output flange matches ISO 5211 valve flanges from F03 to F25. Modular design allows retrofitting in place of other actuators.

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