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A German-made reciprocating triplex plunger pump.

Spheroidal cast iron crankcase with sight glass and vented dipstick; forged, through-hardened, ground and polished crankshaft; bronze connecting rods; hardened stainless steel plunger bases; solid ceramic plungers; nitrile with fabric reinforcing; duplex steel valves; machined stainless steel manifold.

WARNING: This product might contain a chemical known to the State of California to cause cancer, and birth defects or other reproductive harm. For more information go to

Specification US Metric
Flow18 GPM68.1 L/min
Maximum Discharge Pressure4350 PSI300 bar
Crankshaft Speed800 RPM
Power55.9 HP41.7 KW
Max Temperature140 °F60 °C
Inlet Port Size(2) 1-1/2" NPT
Discharge Port Size(2) 1" NPT
Plunger Diameter1.1 in.28 mm
Stroke1.89 in.48 mm
Maximum Inlet Pressure90 PSI6 bar
Crankshaft Diameter42 mm
Crankshaft RotationTop of Pulley Towards Manifold
Crankshaft MountingEither Side
Crankcase Oil Capacity US1.1 gal 4.2 L
Weight309 lbs.140 kg
Manifold Material Stainless Steel
Crankcase Material Spheroidal Cast Iron
Plunger Material Solid Ceramic Oxide
Valve Material Duplex Steel
Seal Material Nitrile with Fabric Reinforcing
The repair kits listed to the right are available for this pump. If you need further information about these repair kits, or have questions about other specific parts for your pump, please contact you local Giant distributor or contact Giant customer service.
Plunger Packing Kit – Part #09302
41A 07721 O-Ring 3
41B 13223 Support Ring 3
41C 12055 O-Ring 3
41D 07693 Support Ring 3
44 13369 V-Sleeve 6
45 13228 Leakage Seal 3
Valve Assembly Kit – Part #09303
51A 07064 Valve Seat 6
51B 07063 Valve Plate 6
51C 07062 Valve Spring 6
56A 07150 O-Ring 12
56B 06266 Support Ring 3
Oil Seal Kit – Part #09304
32 06118 Radial Shaft Seal 3
32A 13215 Grooved Ring 3
33A 07721 O-Ring 3

Horsepower Specifications

RPM GPM 1000 PSI 2000 PSI 3000 PSI 4000 PSI
400 9.0 6.4 12.9 19.3 25.7
500 11.3 8.1 16.1 24.2 32.3
600 13.5 9.6 19.3 28.9 38.6
700 15.8 11.3 22.6 33.9 45.1
800 18.0 12.9 25.7 38.6 51.4

Images Open in new Window/Tab

  • Dimensional Drawing (Side) Open
  • Dimensional Drawing (Front) Open
  • GP6128 Exploded View
  • GP6128 Parts List
  • GP6128 Torque Specifications


Documents open in new window/tab.

  • Giant Industries Limited Warranty
  • GP6128 Installation Instructions
  • GP6128 Repair Instructions
  • Troubleshooting Guide

Sample Pump

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For 50 years, Giant Pumps has offered the most dependable positive displacement high-pressure triplex pumps available. Designed and built to the highest quality standards, customers count on Giant Pumps products to keep their equipment running. Every design detail of Giant Pumps products is optimized for long-life and reliable performance, making Giant Pumps the most trusted name in high-pressure pumps and systems.

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