How do I choose and airless tip?
The size of an airless fluid tip will depend on the following:
The fluid delivery requirements.
The size of the pattern required.
The viscosity of the material being sprayed.
The type and amount of solids in the material beings sprayed.
The type of filtration in the system.
The pump pressure available
Let’s go through basic tip sizes first.
Fluid tips generally have a size listed in thousandths of an inch. The size is normally the diameter of an equivalent circle. Thus we may have 4 or 5 tips that<have identical opening sizes (ie .015”). While the sizes may be all the same, theshape of the opening is not. Imagine taking a 15 in flexible circle and changingthe shape from a circle to an oval. How many different size ovals could wemake?
Tips may also have an indication of the pattern size or angle of spray. That will vary with the manufacturer.
Looking at Figure 1, the areas of all the circles are the same size.
Tip “A” would provide:
The least amount of resistance
The least amount of "tip plugging"
The least amount of tip wear
The shorter / rounder pattern
Tip “E” would provide:
The highest amount of resistance
The highest chance of "tip plugging"
The highest amount of tip wear
The taller / narrower pattern
Fluid Delivery Requirements
Most manufacturers have charts available that give flow rates for various tipmeasured using oils of a specific viscosity at specific pressures.A good rule of thumb for fluid delivery is:
- Doubling the fluid pressure will result in about a 40 percent increase in delivery.
Pattern Size Requirements
The choice of pattern size typically correlate directly to the job at hand. Mostmanufacturers have several pattern sizes available for a given tip opening. Matchthe size to your job requirements.
Higher viscosity materials will result in lower flow rates. Another factor toconsider is the temperature of the coating material. Higher solids materials will beeasier to spray and atomize better if heated. Check your Technical Data Sheetfor the coatings maximum recommended temperature.
Material solids directly affect the viscosity of the material. Higher solids materialtypically require larger tip openings. The particle size of the pigment will alsodetermine how frequently the tip ‘plugs’. Use larger tip sizes if tip plugginghappens frequently.
Due to the narrow openings of most tips, filtration is highly recommended.Passing the material through a coarse strainer may be adequate on the shorterpattern tips, but a fine filter usually is required for the taller pattern tips.
Use a pump that has enough pressure available to do the job. You should try tosize a pump for no more than 70% of its rated pressure range