Airless Spraying—From Pump to Pattern | Article 4 of 18
Understanding Airless Fan Width and Orifice Size
One Controls the Width. The Other Opens the Gate.
Two airless spray tips can have the same fan width and deliver very different amounts of coating. Two others can have the same orifice size and spread that coating across very different areas.
That is why fan width and orifice size must be understood separately. One helps determine how wide the pattern becomes. The other helps determine how much material can pass through the tip.
Put the wrong two together and you can create slow production, excessive film build, poor control, wasted coating, or a sprayer that spends the day trying to keep up.
Two Measurements—Two Different Jobs
With a common three-digit airless tip number, the first digit relates to the approximate fan width. The final two digits identify the nominal orifice size in thousandths of an inch.
First digit × 2 = approximate fan width in inches
Last two digits = nominal orifice size in thousandths of an inch
Example: A 515 tip indicates an approximate 10-inch fan and a 0.015-inch nominal orifice.
The fan-width calculation is generally based on the gun being held approximately 12 inches from the surface. It is a useful nominal reference—not a promise that every measured pattern will be exactly that width.
What Fan Width Controls
Fan width describes the approximate width of the spray pattern produced under the manufacturer’s reference conditions.
Fan width affects:
- How much surface is covered with each pass
- How much control the operator has on narrow work
- How much coating misses the edges of the workpiece
- How many passes are required to cover a broad surface
- How the material is distributed across the pattern
- The relationship among travel speed, overlap, and film build
A wider fan can improve production on a large surface. A narrower fan can improve control on smaller or irregular surfaces. Neither one is automatically better.
A wide pattern is productive only when most of it lands on the work. If half the fan is spraying past the edges, the coating is moving quickly—but not necessarily profitably.
What Orifice Size Controls
The orifice is the precisely manufactured opening through which the pressurized coating passes. Its nominal diameter is represented by the final two digits of the common tip number.
For example:
- 13 indicates a nominal 0.013-inch orifice.
- 15 indicates a nominal 0.015-inch orifice.
- 17 indicates a nominal 0.017-inch orifice.
- 19 indicates a nominal 0.019-inch orifice.
- 21 indicates a nominal 0.021-inch orifice.
Orifice size influences the amount of material the tip can deliver at a given pressure with a particular coating. A larger orifice generally permits greater material flow under comparable conditions.
Actual flow is also affected by pressure, coating viscosity, temperature, tip design, tip condition, and other system conditions. That is why manufacturer flow charts are more reliable than trying to calculate exact production from the diameter alone.
A Small Diameter Change Is Not a Small Change
The difference between a 0.015-inch and 0.017-inch opening looks almost insignificant when written on paper. It is only two thousandths of an inch.
But the area of a round opening increases with the square of its diameter. A 0.017-inch opening has approximately 28 percent more physical opening area than a 0.015-inch opening.
That does not mean every 0.017-inch tip will deliver exactly 28 percent more coating under every condition. Tip geometry, pressure, coating properties, and manufacturer design also affect actual flow. It does explain why moving up only two tip sizes can create a noticeable change in material delivery.
| Nominal Orifice | Approximate Opening-Area Difference Compared with 0.015 Inch | Practical Meaning |
|---|---|---|
| 0.013 inch | Approximately 25 percent less physical opening area | Can substantially reduce material passage under comparable conditions |
| 0.015 inch | Reference size | Used here only as a comparison point |
| 0.017 inch | Approximately 28 percent more physical opening area | Can create a noticeable increase in material delivery |
| 0.019 inch | Approximately 60 percent more physical opening area | Places significantly greater material demand on the pump |
These percentages compare physical opening areas—not guaranteed flow rates. Use the tip manufacturer’s published flow data when exact delivery information is needed.
Same Orifice—Different Fan Width
Consider three tips:
- 315: approximate 6-inch fan with a 0.015-inch orifice
- 415: approximate 8-inch fan with a 0.015-inch orifice
- 515: approximate 10-inch fan with a 0.015-inch orifice
All three share the same nominal orifice size, but they distribute the coating across different nominal fan widths.
| Tip | Nominal Fan Width | Nominal Orifice | General Character |
|---|---|---|---|
| 315 | Approximately 6 inches | 0.015 inch | Narrower pattern with greater control on smaller surfaces |
| 415 | Approximately 8 inches | 0.015 inch | Middle-width pattern balancing control and coverage |
| 515 | Approximately 10 inches | 0.015 inch | Wider pattern suited to broader surfaces |
Under comparable conditions, the narrower pattern concentrates material over a smaller width. The wider pattern distributes material more broadly.
This does not guarantee an exact film thickness. Travel speed, distance, overlap, pressure, coating properties, and actual tip performance remain part of the result.
Same Fan Width—Different Orifice Size
Now compare:
- 513: approximate 10-inch fan with a 0.013-inch orifice
- 515: approximate 10-inch fan with a 0.015-inch orifice
- 517: approximate 10-inch fan with a 0.017-inch orifice
- 519: approximate 10-inch fan with a 0.019-inch orifice
The nominal fan width remains the same, but the material passage becomes progressively larger.
If travel speed and other conditions remain unchanged, the larger-orifice tip can place more coating across approximately the same width. That can increase wet-film thickness quickly.
It can also increase:
- Material consumption
- The risk of runs and sags
- The demand placed on the pump
- The need for operator speed and control
- The consequences of poor triggering and overlap
The correct question is not, “How large a tip can I install?” It is, “How much material does this coating and surface require?”
Fan Width Changes with Gun Distance
The nominal fan width is commonly referenced at approximately 12 inches from the surface. If the operator moves the gun farther away, the pattern generally becomes wider before reaching the work. If the gun moves closer, the pattern becomes narrower.
Changing distance also changes more than width.
Holding the Gun Too Far Away
Excessive distance may increase overspray, reduce transfer efficiency, allow droplets to dry before reaching the surface, soften pattern control, and contribute to uneven coverage.
Holding the Gun Too Close
Insufficient distance may produce a narrower, wetter pattern that is harder to control. It can contribute to runs, sags, excessive film build, and visible application bands.
Do not use gun distance to force an inappropriate tip to fit the job. Select a suitable fan width and then maintain the recommended, consistent spraying distance.
Fan Width and Overlap Work Together
An airless fan does not normally deposit exactly the same amount of coating at every point across its width. A healthy pattern should distribute material evenly enough that properly overlapped passes produce a uniform film.
Professional technique commonly uses approximately 50 percent overlap, subject to the coating, tip, surface, pattern quality, and application requirements. This means each new pass overlaps about half of the previous pass.
With consistent overlap:
- The pattern edges blend together.
- Thin bands between passes are reduced.
- Coverage becomes more uniform.
- Wet-film thickness becomes easier to control.
A wide tip does not eliminate the need for proper overlap. It simply changes the width of each pass.
Fan Width Does Not Equal Spray Angle
Fan width is the measured width of the pattern at a specified distance from the surface. Spray angle describes how broadly the fan opens as it leaves the tip.
The common first-digit calculation provides a convenient estimate of fan width at the reference distance. It should not be treated as a precise measurement of every actual pattern.
Tip design, manufacturing tolerances, pressure, coating properties, gun distance, and wear can all affect the pattern observed in the field.
Why Tip Wear Changes Both Measurements
The orifice in an airless tip is subjected to high-velocity coating flow. Pigments, fillers, and abrasive materials gradually wear the opening.
As a tip wears:
- The orifice becomes larger.
- Material delivery can increase.
- The fan may become narrower.
- The pattern may lose uniformity.
- Edges may become less clearly defined.
- The pump must supply more material.
- Coating consumption can rise without being immediately noticed.
A worn 515 tip is no longer performing as the original 515 specification intended. The number stamped on the handle does not change, but the opening does.
Matching the Pattern to the Work
| Application | Fan-Width Priority | Orifice Priority |
|---|---|---|
| Large walls and ceilings | Broad coverage without excessive overspray | Sufficient delivery for the coating and production rate |
| Doors and medium panels | Pattern that fits the panel with good edge control | Controlled film build and finish quality |
| Railings, columns, and narrow framing | Narrower fan that stays on the work | Enough delivery without overwhelming the surface |
| Industrial structural steel | Pattern suited to changing shapes and access | Compatible with coating solids and required film build |
| Roof and protective coatings | Coverage appropriate for large surfaces | Large enough for the coating but within pump capacity |
| Fine-finish work | Controlled fan suited to the part | Material delivery compatible with the desired finish |
Common Mistakes That Cost Coating
- Choosing a fan wider than the surface: The coating sprayed past the edges does not contribute to film build.
- Assuming a larger orifice is only slightly larger: A small increase in diameter can create a substantial increase in opening area and material demand.
- Using distance to change the pattern: Moving too far away may widen the fan while increasing overspray and dry spray.
- Ignoring overlap: Even a good fan pattern can produce stripes when passes are not overlapped consistently.
- Trying to correct excess material with faster gun movement: The operator may introduce inconsistent film build while racing to stay ahead of the tip.
- Ignoring tip wear: The stamped number describes the tip when manufactured—not after gallons of abrasive coating have passed through it.
- Exceeding pump capacity: A large orifice can demand more material than the sprayer can supply.
A Practical Selection Check
Before spraying, ask:
- Does the orifice fall within the coating manufacturer’s recommended range?
- Does the fan width fit the surface?
- Can the sprayer support the selected orifice?
- Is the tip family appropriate for the application and desired finish?
- Is the filtration compatible with the coating and tip?
- Is the tip new, serviceable, and free from damage?
- Does the test pattern appear properly atomized and evenly distributed?
- Can the specified wet-film thickness be achieved with controlled technique?
If one of those questions produces an uncertain answer, the tip-selection process is not finished.
Safety Notice: Never Inspect a Pressurized Tip by Hand
Airless spray equipment produces fluid pressure capable of penetrating skin and underlying tissue. Never place a hand, finger, glove, or rag in front of the spray tip. Never use any part of your body to test the pattern, check fluid flow, or locate a leak.
Engage the trigger lock and follow the equipment manufacturer’s complete pressure-relief procedure before removing, reversing, cleaning, inspecting, or replacing the spray tip or guard. Turning off the sprayer does not necessarily release pressure trapped in the gun and hose.
Keep the tip guard and trigger guard installed and functioning. Use only tips, guards, guns, hoses, fittings, and accessories compatible with the equipment and rated for its maximum working pressure.
A suspected injection injury is a medical emergency. Seek immediate emergency treatment. Do not treat the injury as an ordinary cut.
This article provides general educational information. Always follow the current instructions and warnings supplied by the equipment, tip, and coating manufacturers.
Check Your Understanding
- What is the difference between fan width and orifice size?
- How do a 315 and a 515 tip differ?
- How do a 515 and a 517 tip differ?
- Why can a two-thousandths-of-an-inch increase in diameter create a meaningful change?
- How can excessive gun distance affect more than the apparent fan width?
- Why does a worn tip no longer perform according to the number stamped on it?
If you can explain how fan width, orifice size, gun distance, overlap, and tip wear work together, you are beginning to control the pattern instead of merely pointing it.
The Bottom Line
Fan width determines how broadly the coating is distributed. Orifice size determines the nominal size of the passage through which the coating must flow.
A wider fan can improve coverage on large surfaces. A narrower fan can improve control. A larger orifice can increase material delivery, but it also increases demand on the operator and the pump.
The right combination puts the correct amount of coating on the correct area at the required film thickness. That is the difference between moving paint and controlling the application.
Free to Learn. Earned Through Completion.
Finishing Starts With Understanding.
AirSprayTech.com
The Finishing Authority®
© 2026 Azimuth Spray Systems, LLC. All rights reserved.