Description

The Cat Pumps Model 550 is a powerhouse in the 7PFR (Plunger, Flush, Reciprocating) series. This is a solid-shaft, frame-block pump built for industrial continuous duty. It is highly regarded for its “overbuilt” design, making it a staple in car washes and industrial pressure cleaning systems.

Technical Specifications

• Flow Rate: $5.0\ \text{GPM}$ (Gallons Per Minute).

• Pressure Range: $100$ to $3000\ \text{PSI}$.

• Speed: $1415\ \text{RPM}$ (Designed for belt-drive or gearbox setups).

• Shaft Diameter: $24\text{mm}$ (Solid, double-ended).

• Inlet Port: $3/4″\ \text{NPT(F)}$.

• Discharge Port: $1/2″\ \text{NPT(F)}$.

• Crankcase Capacity: $25\ \text{oz}$.

The “Ceramic Plunger” Advantage

The Model 550 uses solid ceramic plungers. In industrial settings, this is critical because:

• Heat Dissipation: Ceramic handles the heat of $24/7$ operation without expanding, protecting the seals from melting or warping.

• Corrosion Resistance: It is immune to the caustic chemicals often used in car washes or industrial degreasing.

• Surface Hardness: The mirror finish reduces friction, which is why these pumps can often run for thousands of hours between seal changes.

Common Service Kits

If you are performing maintenance on a Model 550, these are the part numbers you will likely need:

• Seal Kit (Part #30623): Services the high-pressure and low-pressure seals for all three cylinders.

• Valve Kit (Part #30820): Includes the valves, seats, springs, and O-rings (Two kits are required to service all six valves).

• Oil: Use Cat Pump ISO 68 non-detergent oil to protect the internal sleeve bearings.

Critical Maintenance Tips

• The “14” Reference: You mentioned “14” in your query—this likely refers to the 1415 RPM rating. Running this pump significantly above its rated RPM will cause cavitation and rapid seal failure.

• Belt Tension: If using a belt-drive system, do not over-tighten the belts. Excessive side-load tension can wear out the $24\text{mm}$ crankshaft bearings prematurely.

• Winterization: Because of the ceramic plungers, this pump is very sensitive to freezing. If water freezes inside the manifold, the expanding ice will almost certainly crack the ceramic plungers or the brass manifold itself.

• Inlet Pressure: This pump prefers a positive inlet pressure. Ensure your supply plumbing is at least $3/4″\ \text{ID}$ to prevent starving the pump, which leads to “knocking” and vibration.