Flat Fan Spray Nozzles

A flat fan nozzle produces a flat, elongated sheet of liquid. It is the workhorse pattern for anything that has to be covered evenly on a moving line, washing, rinsing, coating, cooling and dust knockdown all lean on it.

Two things decide whether a flat fan works: the spray angle and the edge distribution. Get either wrong and you either miss coverage or double-dose the middle of the belt.

Spray Angle and Coverage Width

Coverage width is a function of angle and distance. Wider angles cover more ground from the same standoff but lose impact, because the same energy is spread over a longer line.

Spray angle	Coverage at 300 mm	Coverage at 500 mm	Typical use
15°	80 mm	130 mm	High-impact cleaning, cutting jets
25°	130 mm	220 mm	Spot washing, targeted rinsing
40°	220 mm	360 mm	General line washing
65°	380 mm	640 mm	Coating, general coverage
80°	500 mm	840 mm	Wide belt coverage
110°	860 mm	1430 mm	Low-pressure wide coverage
145°	1900 mm	3200 mm	Very wide fogging and rinse curtains

Coverage figures assume spraying perpendicular to a flat surface. Angled installations and overlapping headers change the effective width, which is why header layouts are worth checking rather than assuming.

Tapered Edge Versus Even Distribution

Tapered edge fans thin out towards the ends of the sheet. That is what you want when nozzles are mounted in a row and their patterns overlap, the thin edges blend into a uniform line without a heavy band where they meet.

Even distribution fans put roughly the same volume across the whole width and stop abruptly. These suit single-nozzle duties where there is no overlap to worry about.

Mixing the two on the same header is a common cause of streaking on coated products.

Flat Jet Versus Wide Angle Jet

A narrow flat jet concentrates energy into a thin high-impact line, that is the deburring, descaling and cutting end of the range. Wide angle jets trade that impact for a broad curtain at low pressure, which is what dust suppression and humidification duties want.

The practical rule: if you are trying to remove something mechanically, go narrow and raise pressure. If you are trying to wet something evenly, go wide and drop pressure.

Range Walkthrough: What Each Model Is For

Flow figures are quoted at 3 bar.

FF-15 (15°): the narrowest fan and the most energy per millimetre: an 80 mm band at 300 mm standoff, with an even edge that holds the stripe crisp. Marking, striping, spot jetting and high-impact cleaning. 0.5–8 L/min, 1/8“–1/4“.

FF-25 (25°): the targeted-rinsing step: 130 mm at 300 mm, still high impact per area but wide enough to cover a defined zone. Spot washing and pre-rinse lances. 0.6–12 L/min, 1/8“–1/4“.

FF-40 (40°): general line washing: 220 mm at 300 mm, 1.0–20 L/min, and the first 316L-only body. The width most single-nozzle wash stations are laid out around.

FF-65 (65°): the workhorse: 380 mm at 300 mm, 2.0–35 L/min, tapered edge built to overlap into a uniform sheet. The default angle for coating, washing and rinsing headers , start here if unsure.

FF-80 (80°): wide belt coverage: about 500 mm at 300 mm, 3.0–50 L/min, a 2.0 mm free passage for dirtier water, and the first PP body option for chemical washdown.

FF-110 (110°): low-pressure wide coverage: 860 mm at 300 mm, 1.4 m at 500 mm. The dust-suppression workhorse, one tip curtains a transfer point at 2–4 bar. 4.0–60 L/min, 316L or PP.

FF-145 (145° deflector): the wide end, built differently: a deflector face opens the sheet to roughly 145° and about 1.9 m at 300 mm. A broad low-impact curtain for rinse and fogging duty, with the largest free passage in the line (3.0 mm) for dirty water. 6.0–120 L/min.

FF-HP (15°–40°, hardened SS): the high-pressure cleaning family: hardened stainless shrugs off abrasive erosion while the narrow angle set keeps impact concentrated. Pressure-washer lances, deburring and descaling. 2.0–20 L/min, 1/4“–1/2“.

Application Matrix

Industry	Typical duty	Recommended models	Why
Food & beverage	Conveyor and line washdown, pre-rinse	FF-65 / FF-80, 316L	Even band; no dry lanes or double-dosed seams
Steel & aluminium	Strip and roll cooling in rolling mills	FF-65 / FF-80, 316L	Wide even band prevents hot spots and distortion
Automotive & machinery	High-pressure parts washing, deburring, descaling	FF-15 / FF-25 / FF-HP	Narrow fan concentrates energy; hardened SS for abrasive duty
Coating & finishing	Primer, adhesive and glaze application	FF-15 / FF-25 even edge	Graded coats need the edge to hold, not fade
Mining & quarry	Dust suppression at transfer points and crushers	FF-110 / FF-145, PP	Wide low-pressure curtain; PP shrugs off untreated water
Agriculture	Fertiliser and chemical banding	FF-25 / FF-40 even edge	Stripes mean wasted chemical and uneven crop
Textile	Web moistening and humidity conditioning	FF-65 / FF-80 / FF-110	Broad low-pressure wetting without atomizing into drift
Chemical	Process rinsing and vessel cooling	FF-40 / FF-65, 316L / PP	Coverage and impact balanced; chemistry-matched material

Three-Step Selection Framework

If the full checklist feels heavy, the decision collapses to three questions:

1. What angle? Measure the band you must cover and the standoff you can hold: width = 2 × standoff × tan(angle ÷ 2), or read the coverage table above. Removing something mechanically → narrow 15–40°. Wetting something evenly → 65° and up. Pressure cannot widen the sheet.
2. What flow? Find the model whose 3 bar flow band contains your per-nozzle target, then convert with the square-root rule: 4 L/min at 3 bar becomes about 5.7 L/min at 6 bar. Multiply by nozzle count for the header total and size the pump to hold pressure at that total. Check free passage against the largest particle in the fluid.
3. What material? 303/316L for water and mild duty; PP where chemistry attacks stainless or the water is dirty; hardened SS (FF-HP) where abrasion wears the orifice. Match temperature with margin: PP is rated to roughly 80 °C.

Reference Specifications

Flow figures below are quoted at 3 bar. Flow through a fixed orifice scales with the square root of pressure, so a nozzle rated 4 L/min at 3 bar delivers roughly 5.7 L/min at 6 bar rather than 8.

How to Select a Flat Fan Nozzle

• Target width and standoff distance: these two together set the spray angle. Fix the mounting distance first, since it is usually constrained by the machine.
• Impact required: cleaning duties need narrow angles and higher pressure; wetting duties need the opposite.
• Overlap: if nozzles sit in a row, specify tapered edge and plan the overlap rather than butting patterns together.
• Flow budget: total flow is nozzle flow multiplied by nozzle count. Header sizing and pump capacity fall out of this.
• Fluid and solids: larger free passage resists clogging; strainers belong upstream of small orifices.
• Material: stainless for most duties, hardened or ceramic inserts where abrasive wear dominates, plastics where chemical attack is the concern.

Frequently Asked Questions

What spray angle should I use for a 400 mm wide belt? At 300 mm standoff a 65 degree nozzle gives roughly 380 mm, so one nozzle nearly covers it and two overlapping 40 degree nozzles give a more even result with more impact.

Why does my flat fan pattern look streaky? Usually either mismatched edge types across a header, partial clogging in one nozzle, or patterns butting rather than overlapping. Check the pattern of each nozzle individually against a dry surface.

Can I raise pressure to get more coverage? No. Pressure raises flow and impact but barely changes spray angle. Coverage comes from angle and distance.

What is the difference between a flat fan and a flat jet? They describe the same family. In practice flat jet is used for the narrow, high-impact end and flat fan for the wider, general-coverage end.

Even-edge or tapered-edge: which do I need? Tapered edges are the default and are made to overlap: the thin end of one sheet lands in the middle of its neighbour and the row reads as one band. Even edges hold full density to the boundary, for single-nozzle zones, marking and graded coats. Never mix the two on one header.

Why does my nozzle keep clogging? The orifice is smaller than the particles in the fluid. Free passage across the range runs 0.8–3.0 mm, that figure is the clog ceiling. Fit a strainer upstream rated finer than the smallest orifice, or step up to a model with a larger passage.

How much flow will I get at my pressure? Flow through a fixed orifice scales with the square root of pressure. A tip rated 4 L/min at 3 bar delivers about 5.7 L/min at 6 bar, not 8. Pressure is a weak lever for flow, a strong lever for impact, and it barely changes the spray angle.

What should I send with an enquiry? Band width at a known standoff, flow per metre (or header total and tip count), fluid and temperature, uniformity requirement and water quality. That is enough for a model and a header layout.