A nozzle that is too small increases the pressure beyond what the pump can handle: the regulator constantly discharges and the seals wear out quickly. A nozzle that is too large causes the pressure to drop and cleaning efficiency is lost. The correct size depends on two values written on your machine's data plate: the flow rate (in L/min) and the rated pressure (in bar).
Reading nozzle markings
A high-pressure nozzle carries a 4 or 5-digit code, for example 25045:
- the first digits indicate the spray angle: 0 (pencil jet), 15, 25, 40, or 65°;
- the last three digits indicate the nozzle size: 045 = size 4.5.
A 25045 is therefore a 25° flat fan nozzle, size 045. The larger the size, the more water the nozzle allows through at the same pressure.
Nozzle selection table
Locate your pump's flow rate (row) and its rated pressure (column). Values are indicative, rounded up to the next standard size to avoid exceeding the rated pressure.
| Flow rate | 150 bar | 200 bar | 250 bar | 300 bar | 350 bar | 400 bar | 500 bar |
|---|---|---|---|---|---|---|---|
| 8 L/min | 030 | 025 | 025 | 020 | 020 | 020 | 020 |
| 10 L/min | 040 | 035 | 030 | 025 | 025 | 025 | 020 |
| 11 L/min | 040 | 035 | 035 | 030 | 030 | 025 | 025 |
| 13 L/min | 050 | 040 | 040 | 035 | 030 | 030 | 030 |
| 15 L/min | 055 | 050 | 045 | 040 | 035 | 035 | 030 |
| 18 L/min | 065 | 060 | 050 | 050 | 045 | 040 | 035 |
| 21 L/min | 075 | 065 | 060 | 055 | 050 | 050 | 045 |
| 25 L/min | 090 | 080 | 070 | 065 | 060 | 055 | 050 |
| 30 L/min | 110 | 100 | 085 | 080 | 070 | 070 | 060 |
Example: a 15 L/min pump at 200 bar requires a size 050 nozzle, for example a 25050.
Surface cleaners, dual wands: divide the flow rate
When water exits through multiple nozzles at the same time (two-arm surface cleaner, dual lance), each nozzle only receives a portion of the flow rate. Divide the pump's flow rate by the number of nozzles, then read the table.
Example: 19 L/min pump at 400 bar on a 2-nozzle surface cleaner. Each nozzle receives approximately 9.5 L/min: you need two size 022 nozzles. If this size is not available, choose the next size up (025): the pressure will be slightly lower, but the pump remains protected.
Which angle should you choose?
- 0° (pencil jet): highly concentrated, for encrusted dirt and surface cleaners. Handle with caution on delicate surfaces.
- 15°: stripping, floors, concrete, stone.
- 25°: the versatile angle for general cleaning.
- 40°: more delicate surfaces, car bodies, cladding.
- 65°: rinsing and low-pressure product application.
Nozzle threading
Also check your lance connection: most flat fan nozzles use a 1/4" male thread, either NPT (tapered) or BSP (parallel). The two are not reliably interchangeable: use the same type as the original nozzle.
Nozzles wear out
Over time, the orifice widens and the pressure drops. If your machine loses pressure without any other fault, start by replacing the nozzle: it is the least expensive part of the circuit.
Find your nozzle in our Nozzles and Turbo Nozzles categories. Unsure about the size? Send us your machine's data plate at contact.surfaned.distribution@gmail.com, and we will tell you the correct part number.