A German-made triplex plunger positive displacement pump with reciprocating plungers for direct or belt drive applications.

Anodized aluminum 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 seals (with fabric reinforcing); stainless steel valves and 316 stainless steel manifold.

Gearbox and bell housings (to connect to gasoline, diesel, electric or hydraulic drive).

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 www.P65Warnings.ca.gov

  • P420A-5121 Exploded View
  • P420A-5121 Parts List
  • P420A-5121 Torque Specifications

Sorry, there are no accessories associated with this product.

  • Giant Industries Limited Warranty
  • P420A-5121 Installation Instructions
  • P420A-5121 Repair Instructions
  • Troubleshooting Guide


U.S. Metric
Flow 12.8 GPM 48.4 L/min
Maximum Discharge Pressure 2175 PSI 150 bar
Crankshaft Speed 1450 RPM
Maximum Inlet Pressure 145 PSI 10 bar
Maximum Temperature 158 ºF 70 ºC
Plunger Diameter 0.98″ 25 mm
Stroke 0.94″ 24 mm
Crankshaft Diameter 1.10″ 28 mm
Crankshaft Rotation Top of Pulley Towards Manifold
Key Width 0.315″ 8 mm
Crankshaft Mounting Either Side
Inlet Ports (2) 1″ BSP
Discharge Ports (2) 3/4″ BSP
Crankcase Oil Capacity 27 fl. oz. 0.8 L
Weight 36.6 lbs. 16.6 kg
Volumetric Efficiency @ 1450 RPM 0.95
Mechanical Efficiency @ 1450 RPM 0.86
Key Component Material
Manifold Stainless Steel
Plungers Solid Ceramic Oxide
Valves High Grade Stainless Steel
Seals Nitrile With Fabric Reinforcing
Gear End Aluminum

Click the image to enlarge


RPM GPM 1000 PSI 1500 PSI 1700 PSI 2175 PSI
785 6.9 4.8 7.1 8.1 10.4
900 7.9 5.4 8.2 9.3 11.9
1010 8.9 6.1 9.2 10.4 13.4
1120 9.9 6.8 10.2 11.6 14.9
1240 10.9 7.5 11.3 12.8 16.4
1450 12.8 9.0 13.2 15.1 19.2

Horsepower Requirements

The ratings shown are the power requirements for the pump. Gas engine power outputs must be approximately twice the pump power requirements shown above.

We recommend a 1.15 service factor be specified when selecting an electric motor as the power source. To compute specific pump horsepower requirements use the following formulas:
Electric HP = (GPM X PSI)/1450
Gas HP = (GPM X PSI)/1100

*Engine power varies based on horizontal or vertical orientation, as well as by makes and models from each manufacturer.


Plunger Packing Kit – Part #09653-0021
21 07266-0001 O-Ring, Viton 3
23 12254-0020 V-Sleeve, Teflon 3
23B 12255-0020 Weep Seal, Teflon 3
24 08376 Pressure Ring 6
Valve Assembly Kit – Part #09655
27A 08408-0100 Valve Assembly, Complete 6
33 07214 O-Ring 6
Oil Seal Kit – Part #09641
19 05444 Oil Seal 3

Repair Kits Available

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.

Service & Repair

Giant provides service on each pump and accessory that we sell. Many basic repair procedures are covered in the Giant repair manual. For all other questions on service or repair needs please contact your local Giant distributor.