Cat Pumps Model 350 Plunger Pump — 5 Frame Triplex High-Pressure Pump
The Cat Pumps 350 is a 5 Frame triplex plunger pump built for operators who need steady, dependable pressure hour after hour. Rated at 5 GPM with a working range of 100 to 1500 PSI at 1725 RPM, it sits in the sweet spot for equipment that runs long shifts without a lot of fuss. The three-plunger design keeps flow smooth and pulsation low, which means less stress on hoses, fittings, and downstream components, and a noticeably quieter machine on the floor.
Inside, the 350 uses solid ceramic plungers, 304 stainless steel valve assemblies, and a brass manifold, with a lightweight die-cast aluminum crankcase holding 18 ounces of oil. High-pressure seals are lubricated by the pumped liquid itself, and pre-set low-pressure seals with secondary external leak protection help keep the crankcase clean. Standard NBR seals handle liquid temperatures up to 160°F, with alternate seal materials available when the application runs hotter.
At just under 20 pounds and roughly 11.7 by 10 by 5.2 inches, the 350 drops into tight equipment packages and accepts belt, clutch, flexible coupling, or bellhousing drive arrangements through its 20 mm shaft. Dual 1/2" NPT(F) inlet ports and dual 3/8" NPT(F) discharge ports give you flexibility in how you plumb it, and the pump's parts availability makes long-term service straightforward. It is a common choice for pressure washers, car wash bays, misting systems, agricultural sprayers, water treatment skids, and general industrial cleaning equipment.
Key Features
- Triplex plunger design for high volumetric efficiency and low pulsation
- Solid ceramic plungers for long wear life in demanding duty cycles
- 304 stainless steel valve assemblies resist wear and corrosion
- Brass manifold construction
- Lightweight die-cast aluminum crankcase
- High-pressure seals lubricated by the pumped liquid
- Pre-set low-pressure seals with secondary external leak protection
- Compact footprint suited to belt, clutch, flexible coupling, or bellhousing drive
- Field-serviceable design with widely available repair parts
Applications
- High-pressure washing and mobile pressure washer systems
- Car wash and vehicle wash equipment
- Industrial and plant cleaning equipment
- Agricultural and horticultural spraying
- Misting and humidification systems
- Water treatment, reverse osmosis, and pressure boosting
- Hydrostatic testing and general water transfer at pressure
- Food processing and sanitation washdown equipment
- Marine and dockside washdown systems where a freshwater high-pressure supply is needed
Specifications
- Model: Cat Pumps 350
- Frame Size: 5 Frame
- Pump Type: Triplex positive displacement reciprocating plunger pump
- Flow Rate: 5.0 GPM (18.9 LPM)
- Pressure Range: 100–1500 PSI (6.9–103 bar)
- Speed: 1725 RPM
- Horsepower Required: 5.1 HP at rated flow and pressure
- Inlet Port Size: 1/2" NPT(F), quantity 2
- Discharge Port Size: 3/8" NPT(F), quantity 2
- Shaft Diameter: 20 mm (0.787")
- Bore: 20 mm (0.787")
- Stroke: 12 mm (0.472")
- Inlet Pressure: Flooded to 60 PSI (4.1 bar)
- Maximum Liquid Temperature: 160°F (71°C) with standard seals; up to 180°F (82°C) with alternate seals
- Crankcase Oil Capacity: 18 oz (0.55 L)
- Plungers: Solid ceramic
- Valves: 304 stainless steel
- Manifold: Brass
- Crankcase: Die-cast aluminum
- Seals: NBR (Buna-N) standard
- Weight: 19.8 lbs (9 kg)
- Dimensions: 11.71" x 10.0" x 5.24" (297.5 x 254 x 133 mm)
Frequently Asked Questions
Q: Does the Cat Pumps 350 ship with crankcase oil installed?
A: No. The pump ships dry, so the crankcase must be filled to the sight glass level with the correct pump oil before the first start. Running it dry, even briefly, will damage the crankcase components.
Q: Can the 350 be run at a speed lower than 1725 RPM?
A: Yes. Flow scales roughly in proportion to speed, so slowing the pump reduces GPM while pressure capability stays governed by the unloader or regulator setting. Many operators intentionally run below rated speed to extend seal and valve life.
Q: What kind of inlet supply does this pump need?
A: The inlet must be flooded, meaning the supply feeds the pump under positive head, and it can be pressurized up to 60 PSI. Adequate inlet plumbing size and a clean supply are the two biggest factors in avoiding cavitation and premature seal wear.
Q: Is a pressure regulator or unloader required?
A: Yes. Because this is a positive displacement pump, it will keep moving liquid regardless of downstream restriction, so a properly sized unloader or regulator plus a safety relief valve is essential to protect the pump and the system.
Q: Will the 350 handle liquids other than water?
A: It handles a range of mild solutions and detergents when the seal material is matched to the fluid. Standard NBR seals cover many water-based applications, and alternate seal packages are available for higher temperatures or more aggressive chemistry.
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