Cat Pumps 271 3 Frame Triplex Plunger Pump
The Cat Pumps 271 is a compact 3 Frame triplex plunger pump built for operations that demand clean, consistent high-pressure flow without the bulk of a larger pump. Rated at 3.5 GPM and up to 1500 PSI at 1420 RPM, it fits neatly into equipment where space is limited but duty cycles are long. The 316 stainless steel inlet and discharge manifolds paired with solid ceramic plungers give it the corrosion resistance needed for demanding fluids, which is why it turns up in reverse osmosis skids, deionized water systems, misting and humidification equipment, chemical transfer setups, and industrial washing lines just as often as it does on a boat.
What separates the 271 from centrifugal or diaphragm alternatives is how it behaves under load. Positive displacement means flow stays steady as pressure climbs, and the triplex crankshaft design smooths out pulsation so downstream nozzles, membranes, and instruments see a stable pressure signal. The concentric plunger design and pressure-lubricated crankcase reduce seal wear over time, and with 15 ounces of ISO 68 hydraulic oil in the crankcase the pump handles continuous-duty service comfortably.
Installation flexibility is a practical advantage here. The 0.650" solid shaft accepts belt drive, clutch, flexible coupling, or bellhousing arrangements, with pulley mounting available on either side of the pump. Dual 1/2" NPT(F) inlet ports and dual 3/8" NPT(F) discharge ports simplify plumbing in tight enclosures, and at 13.4 pounds the 271 is light enough to mount on portable carts and mobile skids. Every unit is designed for serviceability, with rebuildable seal and valve assemblies that keep the pump in service for years rather than requiring replacement.
Key Features
- Triplex positive displacement design delivers smooth, low-pulsation flow
- 316 stainless steel inlet and discharge manifolds resist corrosion and aggressive fluids
- Solid ceramic plungers for long seal life and superior wear resistance
- 316 stainless steel valves and springs throughout the fluid end
- Pressure-lubricated crankcase supports continuous-duty operation
- Compact, lightweight 3 Frame footprint at 13.4 lbs
- Solid shaft accepts belt, clutch, flexible coupling, or bellhousing drive
- Pulley mounting available on either side for installation flexibility
- Dual inlet and dual discharge ports simplify system plumbing
- Fully rebuildable with available seal, valve, and plunger service kits
Applications
- Reverse osmosis and membrane feed systems
- Deionized and demineralized water pressurization
- Misting, fogging, and humidification systems
- Industrial parts washing and surface cleaning
- Chemical injection and transfer
- Hydrostatic testing equipment
- Agricultural spraying and crop protection
- Car wash and vehicle cleaning equipment
- Dust suppression systems
- Marine washdown and desalination feed service
- OEM high-pressure equipment integration
Specifications
- Model: 271
- Frame: 3 Frame
- Pump Type: Triplex positive displacement plunger pump
- Volume: 3.5 GPM / 13.2 LPM
- Pressure Range: 100–1500 PSI / 6.9–103 BAR
- Rated RPM: 1420 RPM
- Alternate Rating: 4.2 GPM at 1000 PSI, 1725 RPM
- Inlet Ports: 2X 1/2" NPT(F)
- Discharge Ports: 2X 3/8" NPT(F)
- Bore: 0.709" / 18 mm
- Stroke: 0.500" / 12.7 mm
- Shaft Diameter: 0.650" / 16.5 mm
- Maximum Inlet Pressure: Flooded to 60 PSI / 4.1 BAR
- Maximum Liquid Temperature: 160°F / 71°C with standard NBR seals
- Crankcase Capacity: 15 oz / 0.44 L
- Recommended Oil: ISO 68 hydraulic oil
- Inlet Manifold: 316 Stainless Steel
- Discharge Manifold: 316 Stainless Steel
- Plungers: Solid Ceramic
- Valves and Springs: 316 Stainless Steel
- Seals: NBR standard, FPM / EPDM / high-temperature options available
- Horsepower Required: 2.4 HP at 1000 PSI, 2.9 HP at 1200 PSI, 3.6 HP at 1500 PSI
- Dimensions: 10.28" x 8.78" x 5.35" / 261 x 223 x 136 mm
- Drive Options: Belt, clutch, flexible coupling, bellhousing
Frequently Asked Questions
Q: Can the Cat Pumps 271 run dry?
A: No. The 271 requires a flooded or positively pressurized inlet at all times. Running the pump dry damages the seals and plungers within seconds, so a low-flow or low-pressure inlet safety switch is strongly recommended on unattended systems.
Q: What oil does the 271 crankcase take and how often should it be changed?
A: The crankcase holds 15 ounces of ISO 68 hydraulic oil. The initial change should occur after the first 50 hours of break-in operation, followed by changes every 500 hours or every three months, whichever comes first under normal duty.
Q: Does the 271 need a pressure regulator or unloader valve?
A: Yes. As a positive displacement pump, the 271 will continue moving fluid regardless of downstream restriction, so an unloader valve or pressure regulator sized to the pump's flow must be installed to protect the pump and piping from overpressure when the discharge is closed.
Q: How does the 271 differ from the 231 and 237 in the same 3 Frame family?
A: All three share the same 3 Frame crankcase, bore, stroke, and port sizes. The 271 is a higher-flow 316 stainless steel model at 3.5 GPM, the 231 is a lower-flow stainless model at 2.3 GPM, and the 237 uses nickel aluminum bronze construction instead of stainless steel.
Q: Can this pump handle seawater or chemically aggressive fluids?
A: The 316 stainless steel fluid end and ceramic plungers give the 271 good resistance to seawater and many chemicals, though seal material should be matched to the specific fluid. FPM, EPDM, and other elastomer options are available where standard NBR seals are not chemically compatible.
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