GP Polymer Series

The GP Series line of glass reinforced polypropylene actuators (a.k.a. GRPP) are designed to withstand extremely difficult and acidic corrosive environments. Available in three sizes, your applications requiring GRPP polymer plastics with extreme corrosion resistance are covered with up to 500 in-lbs of torque (Double–Acting).

Features and Benefits

Compact Design

Max-Air GRPP Series rack & pinion polymer actuators produce linear torque output in a compact design utilizing the same body and end caps for double acting and spring return models.

Namur Mounting

Each Max-Air GRPP actuator comes standard with NAMUR VDI/VDE 3845 mounting standard on all sizes. No special blocks are required to mount solenoid valves, limit switches or positioners. Air connections are ¼” NPT as standard.

Stainless Steel Pinion

Each GRPP actuator comes standard with a 316 SS pinion.

ISO 5211 Valve Connection

The female output drive is standard with a double square output drive, according to ISO 5211 guidelines. Direct mounting ball valves is simple and quick.

High Cycle Bearings

Shaft bearings isolate the pinion gear from the housing and support the shaft for high cycle applications.

Rugged Tooth Design

The pinion teeth are engaged the full length and stroke of the piston. The pinion height allows manual override without the need to remove the visual position indicator.

High Visibility Beacon

A simple and compact visual indicator comes standard on each unit.

High Cycle Wear Pads

Pistons incorporates impressive double wear pads to separate the rack from the actuator wall and serve as both guide and wear bearings.

Pre-Loaded Spring Cartridges

Epoxy coated automotive grade steel springs are preloaded for safety in a specially designed cartridge using non-metallic materials. The stainless steel end cap fasteners are extra-long to allow for spring relaxation. All parts are corrosion resistant.

Alternative Operating Media

Air pressure operation (lubricated if necessary) from 1 to 8 bar (40 PSI to 120 PSI), and also possible to use hydraulic oil or water at the same pressure limits.

Stainless Steel Fasteners

All external fasteners are corrosion resistant stainless steel as standard.


All units are externally marked with a progressive and traceable serial number, with the year of manufacture visually coded into the first two digits.

Quality Assurance

100% of all units are factory pressure and leak tested, and individually boxed for safe shipment.


Max-Air offers a wide range of adapters for many different sizes and types of valves. Please call the factory for details.