Datasheet summary
781-781K
PDF datasheet mirror for 781-781K (CAT Pumps). Verify with OEM before design.
Summary
Product identification
- 8 Frame Block-Style Stainless Steel Plunger Pump
- Models:
- 781: Standard Brass Model
- 781K: Flushed Model
Operating limits
- Flow: 4.5 gpm (17 lpm)
- Pressure Range: 100 to 5000 psi (7 to 345 bar)
- Inlet Pressure Range: Flooded to 40 psi (Flooded to 2.8 bar)
- RPM: 1700 rpm
- Maximum Liquid Temperature: 160°F (71°C)
- Note: For temperatures above 130°F, consult Cat Pumps for inlet conditions and elastomer recommendations.
Mechanical / hydraulic
- Bore: 0.551" (14 mm)
- Stroke: 0.945" (24 mm)
- Crankcase Capacity: 25 oz. (0.75 l)
- Inlet Ports (2): 1/2" NPTF
- Flushing Ports (2) (K Models only): 1/8" NPTF
- Discharge Ports (2): 1/2" NPTF
- Shaft Diameter - Single End: 0.945" (24 mm)
- Weight: 48.1 lbs. (21.8 kg)
- Dimensions: 13.15 x 9.25 x 6.06" (334 x 235 x 154 mm)
Electrical
The following table outlines electric horsepower requirements using a 1725 rpm motor and a 10" O.D. pump pulley:
| Flow (U.S. gpm / lpm) | Pressure (psi / bar) | HP Required | Pump rpm | Motor Pulley O.D. |
|---|---|---|---|---|
| 4.5 / 17 | 3000 / 210 | 9.3 | 1700 | 9.5 |
| 4.5 / 17 | 3500 / 245 | 10.8 | 1700 | 9.5 |
| 4.5 / 17 | 4000 / 275 | 12.3 | 1700 | 9.5 |
| 4.5 / 17 | 5000 / 345 | 15.4 | 1700 | 9.5 |
| 4.0 / 15 | 3000 / 210 | 8.2 | 1511 | 8.5 |
| 4.0 / 15 | 3500 / 245 | 9.6 | 1511 | 8.5 |
| 4.0 / 15 | 4000 / 275 | 11.0 | 1511 | 8.5 |
| 4.0 / 15 | 5000 / 345 | 13.7 | 1511 | 8.5 |
Features
- Triplex design delivers high efficiency and low pulsation.
- Durable V-Packings are lubricated and cooled by the liquid being pumped.
- Pre-set Lo-Pressure Seals provide secondary protection against external leaks and require no packing adjustment.
- Special high-density, polished, concentric plungers provide a true wear surface and extended seal life.
- Optimal FPM and EPDM elastomers for compatibility with many liquids and temperatures up to 200°F.
- Manifolds are 316 SS block-style for long-term, continuous duty and corrosion resistance.
- 316 SS valves and seats provide corrosion-resistance, ultimate seating and extended life.
- Specially formulated, Cat Pump exclusive, V-Packings offer unmatched performance and seal life.
- Flushed K Models: Special ported inlet manifold permits an external flush liquid, providing cooling for high-temperature liquids and low lubricity liquids (e.g., DI water).
Parts and Materials
An extensive parts list is provided, detailing components, part numbers, descriptions, quantities, and materials for both 781 and 781K models. Material codes are also defined (e.g., AL=Aluminum, CC=Ceramic, EPDM=Ethylene Propylene Diene Monomer, FPM=Fluorocarbon, NBR=Medium Nitrile (Buna-N), PTFE=Pure Polytetrafluoroethylene, SS=316SS). See the official PDF for exact tabulated values.
Safety Notes
All high-pressure systems require a primary pressure regulating device (e.g., regulator, unloader) and a secondary pressure relief device (e.g., pop-off valve, relief valve). Failure to install such relief devices could result in personal injury or damage to the pump or property. Users should read all CAUTIONS and WARNINGS before commencing service or operation of any high-pressure system.
Disclaimer: This summary is based on extracted text and may not include all figures, footnotes, or the latest revisions from the original OEM PDF. Contractual data must always match the specific OEM PDF revision used on the project.
Official datasheet (PDF)
Curated from selected public technical reference material for discovery and preliminary comparison. This summary is not a substitute for a current certified manufacturer datasheet. Verify revisions and design limits before use.