Choosing a pressure washer pump means picking from a catalog that runs from 2.1 GPM for a small hot water cart up to a 44 GPM industrial unit, and from 1,000 PSI sanitary rinse up to 7,250 PSI hydroblasting. That is a wide span, and series names like RKV, XWP, SHP and RTX do not tell you much on their own.

Here is how the range is actually organized, with real numbers instead of adjectives, so you can find your tier in about a minute.

Find your tier first

Gas engine replacement pumps

These are the bolt-on replacements for a washer that already has a working engine. Hollow shaft, 3/4 inch or 1 inch, spinning at engine speed.

• RXV25G30D-EZ, 2.5 GPM at 3,000 PSI, 3/4 in hollow shaft
• RXV3G30D-EZ, 3.0 GPM at 3,000 PSI
• RXV35G30D-EZ, 3.5 GPM at 3,000 PSI

If you are building rather than repairing, the boxed pump packages ship with the unloader, fittings, bolts, garden hose adapter and break-in oil already matched. RSV3G27D-PKG at 3.0 GPM / 2,700 PSI suits a 6 to 9 HP engine; RKV4G40-PKG at 4.0 GPM / 4,000 PSI needs a GX390 class engine; RKV5G32D-VRT3PKG pushes 5.0 GPM at 3,200 PSI for surface cleaner work.

Commercial and industrial electric

Belt or coupled drive at 1,450 or 1,750 RPM, solid shaft, rebuildable. This is where flow starts to matter more than pressure, because most of these run surface cleaners and washdown lines.

• XWL series, 11 to 13 GPM at 2,200 to 3,000 PSI. XWL42.15N is the common one.
• XWP series, high volume at lower pressure. XWP55.14N runs 14.5 GPM at 2,000 PSI, XWP70.12N 18.5 GPM at 1,740 PSI.
• RF series, the pressure end of industrial. RF27.400N does 7.1 GPM at 5,800 PSI on a 30 mm shaft.
• RTF and RTX, the volume end. RTF165N moves 44 GPM at 1,500 PSI.

Ultra high pressure pumps

Above about 5,000 PSI you are no longer cleaning, you are cutting. RGX1550N and SHP1550HN both deliver 4 GPM at 7,250 PSI; SHP2250HN steps to 5.8 GPM at the same pressure. Everything downstream, hose, gun, fittings, has to carry the same rating. This is the tier where mismatched components get people hurt.

Hot water and stainless pressure washer pumps

Two different problems that often get confused. Hot water is a temperature problem: seals, valves and hoses have to be rated for it. Stainless is a chemistry problem: the head has to survive what is in the water.

• Hot water: WHW2115N at 5.55 GPM / 2,200 PSI, WHWL50.15N at 13.2 GPM, and XWL50.15NHT rated to 185°F.
• Stainless head: the RKA-SS and XWLA-SS families, for food plants, dairy, marine and chemical washdown.

Hydraulic drive

Worth choosing when the truck or machine already has hydraulics. No second engine, no extra fuel, no second thing to start on a cold morning. HYD-XM1515 at 4 GPM / 3,000 PSI covers compact service bodies; HYD-RTD100.200 at 25 GPM / 2,900 PSI covers large mobile rigs. The HYDBK base kits handle the alignment, which is the part that ruins hydraulic builds when it is done by eye.

Choosing, in four questions

1. How much area? Flow covers area. If you are rinsing long lines or big pads, buy GPM before PSI.
2. What are you removing? Loose dirt needs 1,500 PSI. Baked-on grease needs 3,000. Coatings need 5,000 and up.
3. What power do you already have? Engine HP, motor HP, or hydraulic flow sets your ceiling. EBHP is GPM x PSI / 1,460, and your motor should sit 10 to 20 percent above it.
4. What is in your water? Salt, caustics or sanitizers mean stainless. Clean municipal water does not.

Then add the protection: a regulator or unloader sized to your flow, a thermal relief valve, and inlet filtration. Those three parts cost less than one rebuild.

Not sure which tier you are in? Send your engine or motor size, your current pump model, and what you are cleaning, and you will get a specific answer rather than a category.