You pick up a pressure washer nozzle chart and it looks like a grid of numbers: orifice sizes down one side, pressures across the top, and a block of flow figures in between. Most people read exactly one cell — the one that matches their machine — and stop. That is how pumps get wrecked and how cleaning jobs stall. The chart is not a lookup table for one number; it is a map of the relationship between the tip you fit and the machine you own.
This guide is for anyone who has to size a tip from a pressure washer nozzle chart and would rather not learn the hard way what happens when the orifice is wrong. We will cover what the chart actually plots, why the orifice size matters more than the spray angle, and how to read it so the pump stays alive and the surface still comes clean. We will also connect it to tank work, because a tank cleaning nozzle for pressure washer duty lives or dies by the same math.
What the Chart Actually Plots
Every pressure washer nozzle chart is built on one physics relationship. For a given orifice, flow scales with the square root of pressure:
Q = k × √P
where Q is flow, P is pressure, and k is set by the orifice size. The chart just tabulates that formula for the common orifice sizes and the pressures people actually run. The columns are pressure; the rows are orifice size; the cells are the flow you get.
The trap is that people read the chart as “which tip fits my machine” when they should read it as “which tip lets my machine reach its rated pressure at a flow it can supply.” Those are different questions, and the second one protects your pump.
The Orifice Size Is the Real Decision
The spray angle — the 0°, 15°, 25°, 40° you see colour-coded on the rack — decides the shape of the fan and how hard it hits. The orifice size decides whether the pump survives. Two nozzles can share the same 25° angle and throw completely different loads at the same machine because their orifices differ by half a size.
A too-small orifice restricts flow. The pump builds pressure past its rating trying to push liquid through a hole that is too tight, and an unloader that is tired or mis-set lets it overspeed. That is how seals blow and crankshafts fatigue. A too-large orifice lets too much flow through, the pressure never climbs to the cleaning threshold, and you stand there with a wide wet fan doing no work. The pressure washer nozzle chart exists to keep you between those two failures.
Read It Backwards From Your Machine
Start from the two numbers your pump actually has: its maximum rated pressure and its maximum rated flow. Now find the orifice row whose chart values land at or just under both of those at your working pressure. You are not matching a single cell; you are finding the orifice whose entire row stays inside your machine’s envelope.
If your chart says a 3.0 orifice at 2,800 psi flows 3.3 GPM and your pump is rated 4 GPM at 3,000 psi, that orifice is safe — it leaves headroom. If a 2.5 orifice at the same pressure wants 4.0 GPM, you are asking the pump to deliver its absolute maximum every time you pull the trigger, with no margin for a warm day or a long hose. Margin is what keeps high pressure tank cleaning nozzles and washer tips running for years instead of seasons.
Why the Angle Comes Second
Once the orifice is safe, the angle is a cleaning-choice question, not a survival question. A 0° or 15° pencil concentrates impact for stripping; a 25° or 40° fans the energy out for washing a broad surface. For tank bodies and vessel exteriors you typically want a narrower, harder cone to reach the curve and knock residue, which is exactly the regime a tank cleaning nozzle for pressure washer use is built around.
But none of that matters if the orifice is wrong, because the machine will never reach the pressure the angle assumes. Read the chart for the orifice first, then pick the angle for the job. That ordering is the difference between “I read the chart” and “I wrecked a pump reading the chart.”
The Colour Codes Are a Shortcut, Not the Law
The coloured tips are a convenience for angle, not a specification for orifice. Two red tips from different brands can carry different orifice sizes, and a chart from one manufacturer will not match another’s colour convention exactly. Always confirm the stamped orifice number against your pressure washer nozzle chart, not the colour of the plastic.
This matters most when you are buying replacements in bulk or mixing brands across a fleet. The angle might look identical on the rack; the orifice — the thing that actually loads the pump — can be quietly different, and the chart is the only place that difference shows up as a flow number.
Connecting the Chart to Tank Cleaning
Tank cleaning nozzles fed by a pressure washer follow the same rule, just upside down: the machine sets the envelope, and the tip must sit inside it. A tank cleaning machine nozzle that is too small for the washer will overpressure the unit; one too large will never build the impact needed to throw water across a 10 m vessel wall. Tank washer setups that read the chart properly match the orifice to the washer’s flow ceiling, then choose the rotary or static head for the reach the vessel needs.
The pressure washer nozzle chart is your first line of defence here too. Size the orifice from the chart, choose the head for the tank, and you get cleaning power without a pump that groans every time it fires.
A Two-Minute Check Before You Fit a Tip
Before you trust any tip to your machine, do this: find your pump’s rated pressure and flow, locate the orifice row on the chart that stays under both, confirm the stamped orifice matches that row (not just the colour), and only then pick the angle for the surface. If the chart shows your chosen orifice wanting more flow than the pump can give, step up one orifice size and re-check. That two-minute read saves a multi-hundred-dollar pump.
The Hose and Unloader Quietly Rewrite the Chart
Two things between the pump and the tip move the real numbers off the printed chart. A long or narrow supply hose drops pressure at the gun — sometimes by hundreds of psi on a 100 ft run — so the tip never sees the pressure the chart assumes. And the unloader, which dumps excess flow to keep pressure stable, only works if it is set for your orifice; set it for a smaller tip than you fit and it cycles constantly, set it for a larger one and the pump never reaches rated pressure.
So reading the pressure washer nozzle chart honestly means reading it for the pressure at the nozzle, not the pressure on the pump badge. Measure at the gun, then pick the orifice for that number. A tank cleaning nozzle for pressure washer duty inherits the same caution: size it for the pressure that actually arrives, not the one on the nameplate.
For heads and nozzles sized for vessel and tank duties, see our tank cleaning nozzles. If you are matching a washer to a specific tank or vessel and want the orifice and head sized together, reach our application team with the washer’s rated pressure and flow and we will work the chart with you.