Frequently Asked Questions

Find answers to the most common questions about selecting the right pressure washer parts, maintaining your equipment, choosing the right chemicals, and our shipping & returns policies.

1. Nozzle Selection

How do I choose the right nozzle for my pressure washer?

Nozzle selection depends on three factors: your machine's GPM (gallons per minute), PSI (pounds per square inch), and the spray pattern needed for your application. Use our nozzle sizing charts to match the orifice size to your pump's flow rate. An undersized orifice will over-pressure your system; an oversized one will reduce cleaning effectiveness.

What do the nozzle color codes mean?

Standard color-coded nozzles indicate spray angle:

• Red (0°) – Pinpoint stream; maximum impact for stubborn deposits. Use with caution on delicate surfaces.
• Yellow (15°) – Narrow fan; heavy-duty stripping and concrete cleaning.
• Green (25°) – General-purpose cleaning; siding, vehicles, equipment.
• White (40°) – Wide, gentle fan; windows, screens, and sensitive surfaces.
• Black (65°) – Low-pressure soap/chemical application nozzle.

How do I calculate the correct nozzle orifice size?

Use the formula: match your pump's GPM and PSI rating to the nozzle sizing chart provided on each nozzle product page. As a rule of thumb, higher GPM machines require larger orifice sizes to maintain proper back-pressure. When in doubt, contact us with your pump model and we'll recommend the correct size.

Can I use a nozzle rated for a higher PSI than my machine?

Yes — nozzles are rated for maximum PSI, so using a nozzle rated above your machine's output is safe. However, always match the orifice size to your GPM to maintain proper system pressure.

2. Pump Maintenance

How often should I replace my pump seals and O-rings?

For commercial and contractor use, inspect seals and O-rings every 250–500 operating hours or at least once per season. Signs of wear include water weeping from the pump head, loss of pressure, or visible cracking on rubber components. Preventive replacement is far less costly than pump failure in the field.

How do I find the right O-ring or seal kit for my pump?

Search by your pump brand and model number (e.g., General Pump, CAT Pumps, AR, Comet, Giant, Udor). Each pump brand has model-specific seal kits listed on our site. If you're unsure of your model, check the pump's data plate or contact us — we can cross-reference by serial number for most major brands.

What causes premature seal failure?

• Running the pump dry (always ensure water supply before starting)
• Cavitation from restricted inlet flow or a kinked supply hose
• Chemical incompatibility — certain solvents degrade standard Buna-N seals (consider EPDM or Viton seals for chemical applications)
• Excessive heat from a blocked or bypassed unloader valve

How do I know if my unloader valve needs replacement?

Symptoms of a failing unloader include pressure fluctuation ("surging"), inability to reach rated PSI, or the machine not unloading when the trigger is released. Unloaders are wear items — inspect annually and replace if adjustment no longer holds a stable pressure setting.

What pump oil should I use, and how often should I change it?

Use a non-detergent pump oil (ISO 46 or the brand-specific oil recommended in your pump manual). Change oil after the first 50 hours of operation on a new pump, then every 250–500 hours thereafter. Milky or discolored oil indicates water intrusion — address the seal issue before continuing operation.

3. Chemical Selection & Compatibility

Which chemicals are safe to run through my pressure washer pump?

Always use chemicals specifically formulated for pressure washer use. Avoid bleach concentrations above 6% through pump heads unless the pump is rated for it — high-concentration sodium hypochlorite will degrade standard seals rapidly. For softwash applications, use downstream injection or a dedicated softwash pump to protect your equipment.

What's the difference between upstream and downstream chemical injection?

• Downstream injection introduces chemical after the pump, protecting internal components. This is the most common and safest method for most cleaning chemicals.
• Upstream injection draws chemical through the pump inlet. Only use chemicals rated for upstream application with pumps that have compatible seal materials (e.g., EPDM or Viton).

What chemicals should I use for common cleaning jobs?

• Concrete & driveways: Alkaline degreasers or sodium hypochlorite-based cleaners for organic staining (mold, algae, mildew).
• House washing / siding: Diluted sodium hypochlorite with a surfactant (softwash mix). Always rinse thoroughly.
• Vehicle & equipment washing: pH-neutral or low-pH foaming detergents to protect paint and metal surfaces.
• Grease & oil removal: Alkaline degreasers or solvent-based degreasers rated for pressure washer use.
• Roof cleaning: Low-pressure sodium hypochlorite application — never use high pressure on roofing materials.

Are your chemicals safe for use around plants and landscaping?

Pre-wet surrounding vegetation before applying any cleaning chemical and rinse thoroughly after. Many of our biodegradable surfactants are formulated to be plant-safe when properly diluted. Always check the product SDS (Safety Data Sheet) for environmental precautions — links are available on each chemical product page.

4. Equipment Compatibility

How do I know which parts fit my pump?

Use your pump's brand and model number as the primary reference. Our catalog is organized by brand (General Pump, CAT Pumps, AR, Comet, Suttner, Mosmatic, Giant, Udor, and more). Each product listing includes compatibility notes. If you don't see your model listed, contact us — many parts cross-reference across model families.

Are fittings and hose connections standardized across brands?

Most professional pressure washer equipment uses M22 or 3/8" quick-connect fittings, but thread pitch and seat angle can vary. Always verify the thread type (male/female, NPT vs. BSP) and connection style before ordering. Our product pages specify fitting type and size for all hoses, guns, and lances.

Can I upgrade my pump without replacing my entire machine?

In many cases, yes — provided the replacement pump matches your engine's shaft size, rotation, and mounting configuration, and your frame can accommodate the new pump's footprint. Contact us with your current pump model and desired upgrade specs and we can advise on compatibility.

What's the difference between direct-drive and belt-drive pump configurations?

• Direct-drive pumps connect directly to the engine shaft. They run at engine RPM, are compact and lightweight, but generate more heat and wear faster under continuous commercial use.
• Belt-drive pumps run at a lower RPM via a belt-and-pulley reduction, resulting in cooler operation, longer pump life, and better performance for high-duty-cycle commercial applications.

5. Shipping & Returns

What are your shipping options and delivery times?

Please visit our Shipping Policy page for current shipping options, carriers, estimated delivery times, and any freight requirements for large or heavy items.

What is your return policy?

Please visit our Returns & Refunds page for full details on our return process, eligible items, timeframes, and how to initiate a return.

Do you ship internationally?

Please refer to our Shipping Policy for current international shipping availability and any applicable restrictions.

What if I received the wrong part or a damaged item?

Contact us immediately with your order number, a description of the issue, and photos if applicable. We'll make it right as quickly as possible. See our Returns & Refunds page for the full process.

Still Have Questions?

Can't find what you're looking for? Our team of pressure washer specialists is here to help — whether you need help identifying the right part, matching a seal kit to your pump model, or choosing the correct chemical for the job.

Contact Us and we'll get back to you as quickly as possible. You can also reach us by phone or email — details on our Contact page.