The Fan Width is measured in inches.
When sparying approx 10" from a surface fan width will be double the first digit (5 = 10") Depending on the pressure and coating used the actual width may vary by upto 2". Select according to the type of work being undertaken.
The Orifice controls the amount of fluid that flows through the tip and is measured in thousandths of an inch. The larger the orifice, the more coating that can pass through at any given pressure. Thinner coatings would generally be sprayed using a smaller orifice than heavier ones.
Standard issue with all QTech and TriTech airless sprayers is a 517 tip, this will give a 10” fan and has a 0.017” orifice.
Sizes above and below this should be selected according to the required width of fan and the coating being used.