Flow Line Series 20 and 21 actuators are technically advanced rack and pinion actuators.
Advanced features are employed to provide accurate and dependable control in the harsh applications.

Having a long and trouble free service life is only one of the benefits of using a Flow Line Series 20/21 actuator.
Flow Line rack and pinion opposed-position actuators produce linear torque in a compact design that utilises the same body and end caps for both the double acting and the spring return models. In addition, Flow Line's fully modular control accessories, Series 50 Solenoid Valves, Series 53 Limit Switches, and Series 55/56 Positioners, mount directly to the actuator. Flow Line offers 11 models to precisely match actuator output torque to that of the valve torque eliminating the extreme oversizing of actuation.
Extruded aluminum body is internally machined and lapped to exact specifications. All internal and external surfaces are anodised for corrosion resistance.
Die-cast aluminum end caps and pistons are epoxy powder coated for maximum corrosion resistance.
The bottom plate design, unique to Flow Line, secures a captive pinion and permits direct mounting to Flow Line 70/71 butterfly valves.
The pinion teeth are engaged the full length and stroke of the piston. The pinion height allows for manual operation without disturbing the position indicator.
Stainless steel pinion is standard up to the Model 21, while the Model 26 and larger are supplied with carbon steel/electroless nickel coated pinions.
All pinions are supplied with anti-blowout retention in both directions.
Epoxy coated special steel springs are preloaded with nonmetallic materials. The stainless steel end cap fasteners are extra long to allow for spring relaxation.
Pistons incorporate double wear pads that serve as both guide and wear bearings, Shaft bearings isolate the pinion gear from the housing and support the shaft during high cycle applications.