How to install a spray tip into a spray gun
The spray tips that you use for your airless spray job can make or break your finish. This How-To guide explains why choosing the right spray tip is important, how the three-digit code system works, and which tips are suited to which types of paint job.
Why choosing the right spray tip is important
Using the wrong spray tip can severely affect productivity and user satisfaction. When a tip is too large, it causes overspray, sags, runs and an all-round poor finish. This is problematic for several reasons:
- Overspray wastes product and reduces profitability
- Re-working paint jobs is costly and creates production line bottlenecks
- Painters take pride in their work and re-working is demotivating
Using the right nozzle can prevent all of these issues.
How do spray gun tips work?
The first step to identifying the best tip for your job is understanding how airless spray gun tips work.
As the name suggests, an airless spray pump pressurises paint without the use of air. Instead, the coating is forced through the spray tip orifice (a tiny hole) under extreme pressure. This process atomises the paint and spray particles exit the gun in a fan pattern. The size of the orifice determines the flow rate and width of the fan pattern.
Airless spray tips three-digit system
The key to knowing which airless spray nozzle to use is understanding the 3-digit number that is printed on the tip. In the example below, you can see the number is 517. The first digit (5) tells you the spray angle, from which you can work out the fan width. The following two digits (1 and 7) make up the number 17, which indicates the orifice size.
Working out the spray angle
The first number of the three-digit sequence represents the spray angle in degrees. Add a zero to the digit to get the angle.
Examples:
- 2XX = 20 degrees
- 3XX = 30 degrees
- 4XX = 40 degrees
- 5XX = 50 degrees
How to calculate the fan width
Imperial calculation:
Multiply the first digit by 2 = X inch fan width
So, in the case of a 517 tip, the calculation would be: 5 x 2 = 10-inch fan width.
Metric calculation:
Multiply the first digit by 5 = X inch fan width
In the case of a 517 tip, the calculation would be: 5 x 5 = 25 cm fan width.
NOTE: The fan width is based on holding the gun 12 inches (30 cm) away from the workpiece.
Working out the orifice size
The second two digits in the three-digit sequence tell you the diameter of the graco spray tip orifice in thousandths of an inch. So, a 517 tip has an orifice diameter of 0.017 inches, expressed as 17 thou. To convert inches to centimetres, multiply by 2.5.
Example:
0.017 inches x 2.5 = 0.0425 cm.
NOTE: Always check the manufacturer's details for your airless sprayer as they will often state a maximum tip size. Graco spray tips always include a max size.
The combination of fan pattern and orifice size will determine the thickness of your coating. Your actual flow rate will depend on your spraying pressure, and the type of paint you are using: high pressure equals high flow; heavier paints equals low flow.
Your choice of tip will depend on several factors:
- Size and surface of item that you are coating
- Level of finish that you wish to achieve
- Type of product that you are using.
How to select the correct spray gun tips for your workpiece
If everything in your production line is of the same type and size and uses the same product coating, you can take a 'one size fits all' approach to choosing your spray tips. For paint shops that spray items of different sizes from large flat panels to small and intricate components, you will need a range of tips to achieve the best possible finish.
Choosing spray tips based on what you are coating
The size the item that you are spraying will influence the airless spray gun tip that you use. Here are some general rules of thumb for common types of workpiece:
|
Type of workpiece:
|
Spray tip number:
|
|
Intricate components
These require a low volume and narrow fan width. |
209 for a 4-inch fan width and a 9 thou orifice size.
|
|
Shipping containers
These require a large tip to provide a consistent spray fan and reliable flow of paint. |
517 for a 10-inch fan width and a 17 thou orifice size.
|
|
Structural steel
The majority of structural steel workpieces are beams and columns that require a specified thickness of paint film, but you are also likely to have flanges and brackets thrown into the mix. |
317 for a 6-inch fan width and a 17 thou orifice size.
|
|
Agricultural machinery & construction plant equipment
These types of workpiece involve multiple moving parts and intricate components. They are often high-value items that demand a flawless finish, for which a fine spray pattern and even paint flow is necessary. |
The fan pattern needs to be in the range of 6-8 inches, so the first digit would be between 3-4. The orifice size will vary depending on the type
|
NOTE: It is good practice to test-spray a few workpieces with different tips to gauge which one delivers optimal results.
Choosing spray tips based on the type of coating
Jotun Penguard FC Epoxy Primer - requires 17-21 orifice size tip
Often the type of coating will dictate the tip diameter. For example, high-volume solid paints can only pass through tips with a large orifice. Always check the product datasheet for information on spray tip requirements.
Here are some generally recommended tip sizes for common types of coating:
|
Product type
|
Orifice size
(thou) |
Product type
|
Orifice size
(thou) |
| Acrylics 100%, latex int
|
13 - 15
|
Membrane (heavy)
|
23 - 27
|
| Acrylics (clear)
|
13 - 15
|
Membrane (very heavy)
|
29 - 39
|
| Block fillers
|
25 - 39
|
Oil-based paints
|
13 - 15
|
| Elastomeric polymers
|
25 - 39
|
Polyurethanes
|
13 - 15
|
| Elastomeric polymers (smooth)
|
21 - 25
|
Primers (latex)
|
15 - 17
|
| Enamels (oil-based)
|
13 - 15
|
Primers (oil-based)
|
17 - 19
|
| Epoxy
|
17 - 21
|
Sealers
|
17 - 21
|
| Epoxy (heavy)
|
23 - 27
|
Shellac (clear)
|
09 - 13
|
| Epoxy (high-solids)
|
29 - 39
|
Stains (solid)
|
13 - 15
|
| Heavy latex
|
21 - 25
|
Stains (transparent)
|
11 - 13
|
| Lacquers (clear coat)
|
09 - 11
|
Tung oil (pure thinned)
|
11 - 13
|
| Lacquers (water-borne)
|
13 - 15
|
Varnishes
|
09 - 11
|
Latex paint (exterior) 17 - 19 Varnishes (low-VOC) 13 - 15
Latex paint (interior) 15 - 17 Water sealers (thin, clear) 11 - 13
Membrane 17 - 21
Buy your airless spray gun tips at Ultrimax
We stock a wide range of high-quality airless spray guns and tips. Visit the Ultrimax online store to buy today or join our LinkedIn Professional Painters Forum to get expert help and advice.
Use our video guide to understand Graco Spray Tips
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